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2018-06-01 EARTH Magazine

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RAFTING THE
IDAHO BATHOLITH
FINDING EARTH’S
MISSING MINERALS
EARTH
LAVA SHAPED
LAKE TAHOE
Teaching Geoscience With
VIRTUAL REALITY
/YRIȶȉȦȁ
www.earthmagazine.org
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FEATURES
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REVEALS EARTH’S
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ȶȏ
New discoveries in mineralogy, one
of the oldest human endeavors, are
arising from a new sort of mining
— data mining. Mineralogists are
applying statistical models and
data science techniques to reveal
previously unseen patterns and
clues hidden in mineralogical
databases, and to find undiscovered
minerals. | Timothy Oleson
ȴȶ`+.*1);470&243,
8-*c5.<*1
Virtual and Augmented Reality
Diversify Geoscience Education
ȴȶ
ȏȉ
VOICES
ȁ COMMENT: COULD NASA FIND EVIDENCE OF EXTRATERRESTRIAL
1.+*'=ȶȉȍȉ$
Two upcoming missions will provide the first systematic approach to
searching the atmospheres of exoplanets for signs of life — and they
could find it in the next several decades. | Jacob Haqq-Misra
Ȱȏ GEOLOGIC COLUMN: REBRANDING ALEXANDER
Alexander III of Macedon is a superhero of history, universally known
as Alexander the Great, who was intent upon conquering a bigger
chunk of the planet than anybody before him. But perhaps he wasn’t
so great after all. | Ward Chesworth
Students going out into the field
to gain hands-on experience and
mapping skills is a time-honored
tradition in geology. Now, teachers
are using virtual and augmented
reality technology to bring the field
XSXLIWXYHIRXW`cSarah Derouin
ȏȉ`87&:*1.3,*414,=
Rafting the Salmon River Through
the Idaho Batholith
Rafting down the Main Salmon River,
which courses north and then west
across northern Idaho, takes you by
Precambrian metamorphics and the
granites of the Idaho Batholith. Six to
eight days later, your trip concludes
as you float past what was once the
edge of North America, and over
former island arcs sutured onto the
continent during the Mesozoic.
| Lucas Joel
ON THE COVER: Virtual reality can be used to show students the big picture, outcrop-scale geology, as well as the fine detail of a hand sample.
Credit: K. Cantner, AGI
NEWS
ȦȮ TAKING THE SURPRISE OUT OF SNEAKER WAVES
Ȧȶ SWELLING CLAY SLOWS LANDSLIDES
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ȶ Ȧ ARE DIATOMS TRIGGERING SUBMARINE
1&3)1.)*$
Ȧȴ A NEW LOOK AT
CHEDDAR MAN
Ȧȏ FROM SILVER
TO SNOW: FULL
CLOUD SEEDING
CYCLE OBSERVED
Ȧȍ OLDEST HUMAN
REMAINS
OUTSIDE AFRICA
FOUND IN ISRAEL
ȶȶ
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ȏ FROM THE EDITOR
ȏȁ MINERAL RESOURCE OF
THE MONTH: Chromium
ȍȉ GEOMEDIA: BOOKS:
“Quakeland” Spotlights
Seismic Risk
ȍȦ CONGLOMERATE:
A Geo Word Jumble
ȍȏ DOWN TO EARTH: With
Geologist and Paleontologist
David Wilcots
ȍȮ '*3(-2&70/93*ȦȍȦȟȟȦ
Mount Pinatubo Erupts
Ȱȉ CLASSIFIEDS:
(EVIIVc4TTSVXYRMXMIW
ON THE WEB AT www.earthmagazine.org
From the Editor
B
ig data is now big business, and
it’s a powerful source of insight
that humanity is accessing in ever
more creative ways. As with all
new innovations, whether that power will
be used for good or ill depends on the users’
motivations. Recently, we saw an example of
the latter with the Cambridge Analytica controversy, but big data can also let us explore
ideas and expand our knowledge in ways we Credit: 7EƶMOI(('=&ȴȉ
may have never contemplated before. Today, data analytics is being used to explore
new frontiers in an area of study almost as old as humanity itself — mineralogy.
The idea that many of the minerals that could exist on Earth have not actually
been discovered, that the diversity of mineral species changes over geologic time,
or that there are clear trends in mineral development with changing tectonic conditions may seem mind-blowing. However, when considered geologically, such
ideas actually make a lot of sense and should not be a surprise, even though, until
recently, there may not have been ways to validate them. Now, by applying advanced
data analytics to what we know about minerals, these and many other concepts
are becoming quite tangible and opening up new areas of study in mineralogy.
In “Data-Driven Discovery Reveals Earth’s Missing Minerals,” Timothy Oleson,
EARTH’s acting senior editor, engages with the researchers leading this revolution
to explore the exciting new techniques they’re applying to uncover insights about
mineralogy here on Earth, and even on the far reaches of Mars.
Not moving too far afield, we also have a feature that examines the potential of
virtual and augmented reality technology to revolutionize how geology is taught
in both the classroom and field. In contrast to that, our Travels in Geology feature
showcases a deeply traditional field experience — rafting down the Salmon River
in Idaho. It makes me yearn for my field camp experience rafting the deep gorges
of the Green River to get unprecedented views into the geology of the region.
So whether you are all about new technology, or pining for some dusty old field
experiences, we have something for you this month.
EARTH
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www.earthmagazine.org
earth@earthmagazine.org
PUBLISHER
Allyson K. Anderson Book
EXECUTIVE EDITOR
Christopher M. Keane
EDITOR
Megan Sever
ACTING EDITOR
Sara E. Pratt
ACTING SENIOR EDITOR
Timothy Oleson
ACTING ASSOCIATE EDITOR
Sarah Derouin
ROVING CORRESPONDENTS
Terri Cook
Mary Caperton Morton
DESIGNERS
Nicole Schmidgall
Brenna Tobler
DESIGN INTERN
Tasnuva Elahi
ILLUSTRATOR
Kathleen Cantner
MARKETING/ADVERTISING
John P. Rasanen
CONTRIBUTORS
Callan Bentley
Josh Knackert
Thea Boodhoo
Jane Palmer
Adityarup Chakravorty
Joellen Talbot
Lucas Joel
EDITORIAL EXTERNS
Elizabeth Dengler
Hannah Hagemann
Jerimiah Oetting
Isabella Siemann
Evelien van de Ven
CUSTOMER SERVICE
Nia Morgan
(LVMWXSTLIV20IERI5L)
CONTRIBUTING EDITORS
Callan Bentley
3SVXLIVR:MVKMRME(SQQYRMX](SPPIKI
EARTH Executive Editor
EARTH MW TYFPMWLIH QSRXLP] MR HMKMXEP JSVQEXW .3 ȶȴȮȴȦȍȍȟ JSV E FEWI WYFWGVMTXMSR VEXI SJ
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American Geosciences Institute. To purchase single issues, please inquire at earth@earthmagazine.org.
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other mailing offices. Claims for missing issues will be honored only up to six months. Issues undelivered
through failure to notify EARTH of address change will not be replaced.
Scott Burns
5SVXPERHXEXI9RMZIVWMX]
Jacob Haqq-Misra
'PYI2EVFPITEGI.RWXMXYXISJGMIRGI
Geoff Plumlee
9,ISPSKMGEPYVZI]
Scott Sampson
GMIRGI;SVPH'VMXMWL(SPYQFME
(EREHMER5SWX5YFPMGEXMSRW2EMP&KVIIQIRX3YQFIVȏȉȉȰȍȉȍȰ (EREHMERVIXYVREHHVIWW)5,PSFEP
2EMPȏȟȰȉȶ;EPOIV7SEH;MRHWSV433ȟ&Ȱ/ȴ
Editorial Matter: We encourage readers to alert us to news and photos for possible publication. Opinions
expressed by authors are their own and do not necessarily reflect those of AGI, its staff, its member
societies, or its advertisers. The presence of an advertisement in this magazine does not constitute
EARTH endorsement of the product.
Reproduction: More than one photocopy of an item from EARTH may be made provided that fees are
TEMHHMVIGXP]XSXLI(ST]VMKLX(PIEVERGI(IRXIVȶȶȶ7SWI[SSH)V)ERZIVW2&ȉȦȟȶȴ9&5LSRI
ȟȮȁȮȍȉȁȏȉȉ+E\ȟȮȁȰȏȰȁȰȉȉ&R]SXLIVJSVQSJVITVSHYGXMSRVIUYMVIWWTIGMEPTIVQMWWMSRJVSQ
and is subject to fees by EARTH.
Michael E. Webber
9RMZIVWMX]SJ8I\EWEX&YWXMR
EARTH is printed by American Web, based
in Denver, Colo. EARTHMWTVMRXIHSRȶȉ
VIG]GPIH Ȧȉ TSWXGSRWYQIV [EWXI
paper. All inks used contain a percentage of soy
base. Our printer meets or exceeds all federal
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Standards.
TEKIȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
American Geosciences Institute
The American Geosciences Institute is a nonprofit federation of geoscientific and professional associations that
VITVIWIRXWQSVIXLERȶȍȉȉȉȉKISPSKMWXWKISTL]WMGMWXWERHSXLIVIEVXLWGMIRXMWXW+SYRHIHMRȦȟȏȁ&,.TVSZMHIW
information services to geoscientists, serves as a voice of shared interests in our profession, plays a major role
in strengthening geoscience education, and strives to increase public awareness of the vital role the geosciences play in society’s use of resources,
Member Societies
AASP-The Palynological Society (AASP)
resilience to natural hazards, and the health of the environment.
American Association of Geographers (AAG)
American Association of Petroleum Geologists (AAPG)
American Geophysical Union (AGU)
Executive Committee
American Institute of Hydrology (AIH)
American Institute of Professional Geologists (AIPG)
President Eve S. Sprunt, Eve Sprunt & Associates
American Meteorological Society (AMS)
President-Elect Rodney C. Ewing, Stanford University
American Rock Mechanics Association (ARMA)
Secretary Keri A. Nutter, DOWL
Association for the Sciences of Limnology and Oceanography (ASLO)
Association for Women Geoscientists (AWG)
Treasurer Heidi L. Hoffower, Chevron Corporation
Association of American State Geologists (AASG)
Member
at Large Jonathan D. Arthur, Florida Geological Survey
Association of Earth Science Editors (AESE)
Association of Environmental & Engineering Geologists (AEG)
Member at Large Carolyn G. Olson
Clay Minerals Society (CMS)
U.S. Geological Survey
Council on Undergraduate Research, Geosciences Division (CUR)
Member at Large Diane R. Smith, Trinity University
Environmental and Engineering Geophysical Society (EEGS)
Past President Jean M. Bahr, University of Wisconsin - Madison
Friends of Mineralogy (FOM)
The Geochemical Society (GS)
Chair of AGI Foundation Daniel D. Domeracki, Schlumberger
Geo-Institute of the American Society of Civil Engineers (GI)
Executive Director Allyson K. Anderson Book
Geological Association of Canada (GAC)
American Geosciences Institute
Geological Society of America (GSA)
The Geological Society of London (GSL)
Geoscience Information Society (GSIS)
History of Earth Sciences Society (HESS)
International Association of Hydrogeologists/U.S. National Chapter
(IAH)
International Medical Geology Association (IMGA)
Karst Waters Institute (KWI)
Mineralogical Society of America (MSA)
Mineralogical Society of Great Britain and Ireland (MSGBI)
National Association of Black Geoscientists (NABG)
National Association of Geoscience Teachers (NAGT)
National Association of State Boards of Geology (ASBOG)
National Cave and Karst Research Institute (NCKRI)
National Earth Science Teachers Association (NESTA)
National Ground Water Association (NGWA)
National Speleological Society (NSS)
North American Commission on Stratigraphic Nomenclature
(NACSN)
Paleobotanical Section of the Botanical Society of America (PSBSA)
Paleontological Research Institution (PRI)
Paleontological Society (PS)
Petroleum History Institute (PHI)
Seismological Society of America (SSA)
SEPM (Society for Sedimentary Geology) (SEPM)
Society for Mining, Metallurgy, and Exploration, Inc. (SME)
The Society for Organic Petrology (TSOP)
Society of Economic Geologists (SEG)
Society of Exploration Geophysicists (SEG)
Society of Independent Professional Earth Scientists (SIPES)
Society of Mineral Museum Professionals (SMMP)
Society of Vertebrate Paleontology (SVP)
Soil Science Society of America (SSSA)
United States Permafrost Association (USPA)
www.americangeosciences.org
International Associate Societies
Canadian Federation of Earth Sciences (CFES)
Geological Society of Africa (GSAf)
International Association for Promoting Geoethics (IAPG)
YES Network (YES)
Credit: 'EGOKVSYRHlIQMWEXGLWLYXXIVWXSGOCȮȁȉȦȉȴȏȍ &,.PSKSWLETIMQEKIWPEZE
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TEKIȍ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
DO YOU KNOW
A GEOSCIENTIST DESERVING
RECOGNITION?
Have you considered submitting their name for one of AGI’s awards?
It is never too early to nominate a great colleague for one of the following three
&,.ȶȉȦȟE[EVHW
1
Medal in Memory of Ian Campbell
for Superlative Service to the
Geosciences
3
Outstanding Contribution to the
Public Understanding of the
Geosciences
The Ian Campbell Medal is given in recognition
This award is given for a contribution(s) that
of singular performance in, and contribution
leads to greater public appreciation and better
to, the geoscience profession. Candidates are
understanding of the role the geosciences play
measured against the distinguished career of
MRXLIEǺEMVWSJSYVWSGMIX]8LIGSRXVMFYXMSR
Ian Campbell, whose service to the profession
may be in geoscience as a science or as it
touched virtually every facet of the geosciences.
relates to economic or environmental aspects
of modern civilization.
2
Marcus Milling Legendary
Geoscientist Medal
The submission deadline is February 1, 2019.
Past recipients and more information can be
This medal is given in recognition of :
GSRWMWXIRXLMKLUYEPMX]WGMIRXMǻG
achievements and service to the
geosciences having lasting, historic value;
LMKLEGGSQTPMWLQIRXWMRǻIPHWSJ
found at:
https://www.americangeosciences.org/awards
or you can contact Leigh Sutherland at
LS@americangeosciences.org
expertise as noted by professional societies,
universities, or other organizations; (3) being a
senior scientist nearing completion of, or has
completed, full-time “regular” employment;
and (4) personally able to accept the award.
TEKIȰ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
At this time, AGI would like to celebrate its awardees from the past year:
RUSS SLAYBACK
The 2017 AGI Medal in Memory of Ian Campbell for Superlative Service
to the Geosciences, AGI’s highest award, went to Russell G. Slayback.
He served the American Institute of Professional Geologists in some
c HMǺIVIRX SǽGIW ERH TSWMXMSRW MRGPYHMRK REXMSREP TVIWMHIRX SJ &.5,
His leadership and exceptional service to AIPG and the geosciences
were recognized when he was presented with the Martin Van Couvering
Memorial Award and the highest honor of the bestowed by AIPG, the Ben
H. Parker Memorial Medal. He served the American Geosciences Institute
with the same energy and dedication, serving as an AGI Foundation
Trustee and Chairman of the AGI Foundation, as a member-at-large on
the Executive Committee, and as President of the Institute. In addition, he
has been active in several other professional societies and in state level
advisory committees, as well as in civic activities.
Credit: Courtesy of Russ Slayback
SUSAN KI*FFER
The 2017 Marcus Milling Legendary Geoscientist Medal went
XS)VYWER;IVRIV0MIǺIVGYVVIRXP]E5VSJIWWSV*QIVMXEEXXLI
University of Illinois at Urbana-Champaign, who has achieved
legendary status for contributions to the geosciences over a
lifetime commitment to research and service. Her approach—
MRZSPZMRK ǻIPHI\TIVMQIRXEP ERH XLISVIXMGEP [SVOƴLEW
TVSJSYRHP] MRǼYIRGIH YRHIVWXERHMRK SJ TPERIXEV] MRXIVMSVW
and surfaces, and has highlighted unifying themes across
disciplines. In addition, her service to geoscience positively
impacts both fellow geoscientists and society in general.
Credit: Paul Knauth
IAIN STEWART
The 2017 recipient of AGI’s Outstanding Contribution to the Public
Understanding of the Geosciences Award was Dr. Iain S. Stewart,
Professor of Geoscience Communication at the University of
Plymouth in the United Kingdom. He is known as a presenter
of popular television documentary programs for the BBC. His
“Earth: The Power of the Planet” was a 2007 series nominated
for a BAFTA award, or the United Kingdom’s equivalent of the
Emmy; several other television programs followed. In 2013 Dr.
Stewart was the recipient of the Athelstan Spilhaus Award given
by the American Geophysical Union. In addition to his television
work and writing, he regularly gives public lectures and is very
active in social media.
Credit: Lloyd Russell; photographer for Plymouth
University
TEKIȮ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Comment
(SYPH3&&+MRH*ZMHIRGISJ*\XVEXIVVIWXVMEP1MJIF]ȶȉȍȉ$
/EGSF-EUU2MWVE
E
xoplanet discoveries are featured
almost weekly in the news. With
ground-based observations supplementing the Kepler Space
Telescope during its nine-year mission,
more than 1,000 exoplanets have been discovered. We now know that rocky planets
are commonplace in the galaxy, which
suggests that more than a few should
be situated the right distance from their
host stars to sustain habitable conditions
on the surface. Recent discoveries, such
as the seven planets in orbit around the
red dwarf star TRAPPIST-1, exemplify
the diversity of worlds that we have only
begun to uncover. But, so far, evidence of
extraterrestrial life remains elusive.
Two upcoming missions may change
that, focusing our search on nearby stars,
including low-mass red dwarfs, as well as
stars like our sun. The Transiting Exoplanet Survey Satellite (TESS), which
launched in April, will use a similar method
as Kepler, detecting the faint dimming that
occurs when a planet passes in front of
its host star. During its planned two-year
mission, TESS will provide unprecedented
capabilities to detect the exoplanets nearest
to our solar system.
The other mission is the James Webb
Space Telescope (JWST), the successor
to the Hubble Space Telescope. After
launch, JWST will perform a wide range
of astronomical observations — including
the characterization of exoplanet atmospheres. JWST, which has already been
delayed many times, was scheduled to
launch in 2018 and operate in tandem
with TESS; however, recent technical setbacks have now delayed the launch until
2020. Nevertheless, exoplanet detections
by TESS, and subsequent characterization
with JWST, will provide the first systematic approach to searching a planetary
atmosphere for signs of life.
One thing they will be looking for
is the “smoking gun” signature of life
espoused by many astrobiologists — the
simultaneous presence of methane and
oxygen in a planet’s atmosphere. Atmospheric oxygen originates mainly from
photosynthesis and supports respiration
on Earth, while biology is a significant
source of methane. Methane and oxygen
interact in the atmosphere, and would
become depleted if they were not continually replenished by life. The discovery of
The Transiting Exoplanet Survey Satellite, which launched in April, is the successor to the Kepler Space Telescope and is the most
sophisticated exoplanet-hunting spacecraft yet.
Credit: NASA Goddard Space Flight Center
TEKIȁ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Comment
a water-rich planet, orbiting within the
habitable zone of a sun-like star, with
methane and oxygen observable in its
atmosphere, would represent the first
actual candidate for an inhabited planet.
One thing [the space
telescopes] will be
looking for is the
“smoking gun” signature
of life espoused by many
astrobiologists — the
simultaneous presence
of methane and oxygen
in a planet’s atmosphere.
Planets resembling early Earth could
also provide an alternative scenario for
an inhabited planet, with no atmospheric
oxygen and possibly a thick layer of
organic haze, similar to conditions found
on Titan. Likewise, studies of the past climate of Mars provide scenarios with dense
carbon dioxide atmospheres that could
sustain liquid water oceans and, perhaps,
life. Astrobiologists remain cautious about
over-interpreting any such scenarios and
continually suggest alternative abiogenic
mechanisms that could cause the same
observable signal. Today, theoretical work
by astrobiologists provides a basis for characterizing the “biosignatures” that missions
like TESS and JWST will be looking for
after launch.
Mission studies are currently underway
to prepare for NASA’s next generation of
space telescopes after TESS and JWST.
Three contenders to advance exoplanet
science are the Habitable Exoplanet
Imaging Mission (HabEx), the Large
Ultraviolet Optical Infrared Surveyor
(LUVOIR) and the Origins Space Telescope (OST), all of which would enable
precise characterization of exoplanet
atmospheres far beyond the capabilities
of JWST.
Although TESS could discover hundreds or even thousands of exoplanets
around nearby stars, the limited availability of observing time with JWST to
characterize them might yield
only one or two “Earth twin”
candidates. By contrast, the
HabEx, LUVOIR and OST mission concepts are all intended to
provide a much larger sample
of atmospheric characterizations that will vastly increase
the chances of stumbling upon
a positive biosignature.
The technical details, including the range of observed
wavelengths and mirror diameter, have not been finalized
for any of these missions. The
next few years of mission study
and selection by teams within
NASA will ultimately determine the identity of the next
flagship mission.
Whichever mission —
HabEx, LUVOIR or OST
— is selected, the target launch
date is presently set for 2037.
Engineering challenges and
congressional budget debates 8IGLRMGMERW PSSO YT EX XLI ȰȍQIXIVHMEQIXIV TVMcan sometimes contribute to mary mirror of the James Webb Space Telescope
setbacks, but advanced capa- /;8 HYVMRK MXW GSRWXVYGXMSR MR ȶȉȦȰ (SRWMHIVIH
bilities for studying a plenitude the successor to the Hubble Space Telescope, JWST
of nearby planetary targets has a much larger mirror, and will look at the universe
in great detail could become in infrared wavelengths. Hubble detected primarily
a reality in the near future. optical and ultraviolet wavelengths.
With another five or 10 years Credit: NASA Goddard Space Flight Center/Chris Gunn
for observation and analysis,
we could reasonably be holding class- understanding of planetary systems.
room discussions on the likelihood of Nevertheless, this approach is poised to
life existing on specific exoplanets by detect not just one or two, but a whole
population featuring all the observable
the year 2050.
Observations with the next genera- characteristics of life we know from
tion of NASA missions could provide a our own planet. And we could see such
statistically meaningful sample of poten- discoveries in the coming decades.
tial biosignatures from
the multitude of known
Haqq-Misra is a research sciexoplanets, and enable a
entist with the Blue Marble
quantitative discussion of
Space Institute of Science,
the prevalence of life in
a nonprofit research instithe universe. As with the
tute with an interdisciplinrest of exoplanet science,
ary approach to studying the
the observation of biosigrelationship between earth
natures will likely yield
sys tem science and the
future of humanity. The
unexpected surprises that
defy theoretical predicviews expressed are his own.
tions and challenge our Credit: Gina Riggio
Email: jacob@bmsis.org.
TEKIȟ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
52nd Annual Meeting
Association of Earth Science Editors
Niagara Falls, New York
September 26-29, 2018
Abstracts deadline: August 15, 2018
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News
Swelling clay slows landslides
R
ainfall can trigger landslides, and it can also cause
slow-moving slides to speed
up. But researchers have
observed that rain also appears to cause
landslides composed of clay-rich material
to take longer to start moving, and to
move slower than expected.
To investigate why, William Schulz
of the U.S. Geological Survey (USGS)
Landslide Hazards Program in Golden,
Colo., and his colleagues studied the Two
Towers Landslide in Northern California,
which is representative of thousands of
earthflows worldwide: a mixture of clay,
silt and rock fragments that moves slowly
and persistently. Two Towers measures
approximately 250 meters in length and
averages 40 meters wide and 7 meters
deep. The side boundaries of the slide are
nearly vertical and on average, it moves
less than 1 meter per year.
The researchers measured rainfall at
Two Towers between November 2014
and July 2017 to understand water inputs
at the site. They also noted groundwater
pressure at the landslide’s head, middle and toe; movement; the amount of
soil swelling; and horizontal stresses on
the side-bounding faults. In the lab, the
researchers tested the strength, composition and inherent swell-pressure — how
much pressure the material will exert
after absorbing water.
The lab analysis revealed that much
of the landslide is composed of smectites
— a group of highly expandable clay
minerals — which, when infiltrated by
water, can create very high swell-pressures. In the field, the researchers
observed this same swelling resulting
in high pressures along the landslide’s
side-bounding faults.
Usually, during the rainy season, water
seeps into the main body of a landslide
and increases the water pressure in pore
spaces, which reduces friction until it
becomes weak enough for the mass to
slide. But during and following the rainy season
between October and
April at Two Towers,
sliding for each of the
three years of observation was delayed by
about six to seven months
compared to what was
expected, based on
established studies relating water pressure and
landslide earth movement. The researchers’
new study, published in
Geophysical Research
Letters, suggests that
clay’s swelling potential
might explain the delay
at Two Towers.
The scientists hypothesize that expanding clay
pushes outward on the
Researchers study the Two Towers Landslide in Northern faults that bound the
California, which moves about a meter a year and is repre- sides of the landslide,
sentative of thousands of clay-rich landslides worldwide.
acting as a brake by
increasing resistance.
Credit: William Schulz
With continuing rainfall, however,
increased water pressure in the pores
reduces frictional resistance enough to
overcome the resistance exerted by the
swelling clay, which allows the landslide
to accelerate.
And even when there isn’t enough
rain in a given wet season to surpass the
threshold, when the soil in the landslide
eventually dries out a few months later,
it contracts and the horizontal pressure
decreases, releasing the brakes and allowing the landslide to move.
“The important implication is that
the models that we have been hanging
our hat on for so many years are incomplete,” says co-author Joshua Roering, a
geoscientist at the University of Oregon.
“To assess the stability of a landslide, you
really need to adopt a three-dimensional
perspective [of the slide].”
When the researchers created a
mathematical model of the landslide,
which incorporated the swelling pressure along with recorded groundwater
pressures and measured strengths of the
slide material, they found it correctly
predicted the delayed initiation of the
landslide and its reduced speed. The
model estimated that the swelling added
nearly 9 percent to the total resistance
to landslide motion.
“It is a new and novel mechanism,
which will apply elsewhere,” says Dave
Petley, a natural hazards specialist at the
University of Sheffield in England, who
was not involved in the research. “[This
work] explains the behavior of some
landslides, but not all.”
To fully test their theory, the
researchers would have to conduct
similar investigations on slides composed of less expandable material and
with different geometries, Schulz says.
“Soil swelling may partly determine
timing and speed of many landslides,”
he says. “If this theory holds up, it
really should change the way we try to
forecast [the] timing and mobility [of
clay landslides].”
TEKIȦȶ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Jane Palmer
News
1EZEWLETIH1EOIc8ELSI
W
ith its preternaturally
clear blue waters, Lake
Tahoe is tranquil today,
but the deep lake straddling the border of California and Nevada
was once the site of repeated lava flows. In
a new study, researchers used radiometric
argon dating to describe how episodes of
volcanism created the landscape around
the largest alpine lake in North America.
A small, volcanic field lies along the
northwest shore of Lake Tahoe, where
the lake flows into the Truckee River. In
the new study, published in Geosphere,
the researchers mapped, sampled and
analyzed the succession of lavas that
formed the field. Their work revealed
that the lavas and pyroclastic materials
erupted from seven vents in at least three
episodes of volcanism starting roughly
2.3 million years ago.
Using radiometric dating, the team
constrained the timeline of changing shorelines through these periods of volcanism,
which raised lake levels
above today’s elevation
of 1,897 meters above
sea level. The lake’s
outlet to the Truckee
River was dammed
when the first episode
began about 2.3 million The headwaters of the Truckee River
years ago; this raised begin at the Lake Tahoe dam.
the lake level by about Credit: )MRYVEN0(('=ȶȉ
150 meters, from about
1,896 meters above
sea level to 2,048 meters. Another flow “The timing of this repetitive volcanic
2.1 million years ago dammed it again, rais- activity raises implications for future voling the lake level from about 1,914 meters canic eruptions and their hazards,” said
to 2,073 meters. Then, about 940,000 years co-author James Moore of the U.S. Geoago, another flow raised the lake level to logical Survey in Menlo Park, Calif., in a
2,085 meters. These three raised shorelines statement. “The lake could be dammed
indicate that the present outlet of Lake by lava again, causing extensive shoreTahoe through the Truckee River Canyon line flooding as its level rose, or rapid
has existed for at least 2.3 million years.
dam failure could cause extensive downThe findings may be relevant to stream flooding along the Truckee River
assessing future volcanic hazards around on its path to Reno.”
the now-heavily populated lakeshore.
2EV](ETIVXSR2SVXSR
A new look at Cheddar Man
I
n 1903, a skeleton was found in a limestone cave in Cheddar Gorge, near
Somerset, England. Radiocarbon dating in the 1970s revealed the remains
to be more than 10,000 years old, making it
the oldest near-complete human skeleton
found in Britain. Now, as yet unpublished
research suggests Cheddar Man’s genome
reveals a surprisingly different appearance
for the Mesolithic man from what’s long
been thought, according to researchers
who analyzed DNA from the skeleton.
In 1998, a team from the University
of Manchester sculpted the first reconstruction of Cheddar Man, depicting a
Caucasian-looking man in his 20s with
brown hair, brown eyes and white skin.
The new reconstruction is dramatically
different, depicting a dark-skinned person
with brown hair and blue eyes.
To access Cheddar Man’s DNA, a team
from London’s Natural History Museum
led by Selina Brace drilled a tiny hole
into the ancient skull and harvested bone
powder from an inner ear bone known
as the petrous. The petrous is one of the
densest bones in the human body, where
genetic material is likely to remain well
preserved over long time spans. Researchers then shotgun sequenced the DNA,
compiling many sequenced fragments to
create a nearly complete library of Cheddar Man’s genome. By matching known
genetic markers for physical traits such as
eye, hair and skin color, the team found a
76 percent chance that Cheddar Man had
a notably dark complexion, as well as a
high likelihood he had blue eyes.
“Until recently, it was always assumed
that humans quickly adapted to have
paler skin after entering Europe about
45,000 years ago,” co-author Tom Booth
said in a statement. “Pale skin is better
at absorbing ultraviolet light and helps
humans avoid vitamin D deficiency in
climates with less sunlight.”
Cheddar Man’s dark skin defies conventionally held ideas that Britons have long
been light-skinned.
Credit: l8SQ'EVRIW(LERRIPȏ
Paleoartists Adrie and Alfons Kennis
then applied these findings to create a
new model of Cheddar Man’s face in
full three-dimensional detail. The model
will be featured in a new television documentary, “The First Brit: Secrets of the
10,000 Year Old Man,” and will be on
display at the museum.
TEKIȦȴ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
2EV](ETIVXSR2SVXSR
News
From silver to snow: Full cloud seeding cycle observed
C
loud seeding — adding particles
to clouds to modify precipitation patterns — has been
suggested as a way to trigger
rain and snowfall, which could help
sustain mountain snowpack and water
supplies across the western U.S. However,
it has been challenging to demonstrate
the technique’s effectiveness and efficiency, in part because direct observations
of the full chain of events involved in
cloud seeding have been lacking.
In a new study in Proceedings of the
National Academy of Sciences, researchers
report observations of the entire sequence
of a cloud seeding cycle: from introducing
silver iodide particles into clouds to the
nucleation of ice crystals to the resulting
precipitation hitting the ground.
“We were able to confirm — under
specific circumstances — the basic
hypotheses of what physically happens
when you put seeding material into a
cloud,” says Jeffrey French, an atmospheric scientist at the University of
Wyoming and lead author of the new
study. “Bits and pieces of this process
have been observed before, but never
the entire sequence.”
French and his colleagues used a
combination of airborne and groundbased instruments to study cloud seeding
experiments over the Payette Mountains
in southwestern Idaho, about 80 kilometers north of Boise, as part of the
National Science Foundation-funded
Seeded and Natural Orographic Wintertime Clouds – Idaho Experiment,
or SNOWIE.
Clouds in the study area are usually
orographic, formed by air rising over the
mountains. Orographic clouds contain
supercooled water droplets, which are
smaller than a quarter of a millimeter in
diameter, and have correspondingly small
radar signatures. Ice crystals, in contrast,
can be several millimeters in diameter,
with radar signatures up to a thousand
times larger than those of supercooled
water droplets, which gives researchers
a clear way to distinguish the two.
During the study, a seeding aircraft,
flying roughly perpendicular to the
wind direction, navigated back and forth
through naturally formed clouds, introducing silver iodide particles at specific
time intervals. Simultaneously, a measurement aircraft equipped with sensors
to detect the effects of the seeding flew
perpendicular to the other plane’s flight
path and parallel to the wind direction.
The researchers also monitored the
experiment with two ground-based
stations equipped with X-band radar,
which uses relatively long wavelengths
that allow measurements to be made
from tens of kilometers away, providing
a broad view of the cloud seeding results.
“But greater range comes at the
expense of sensitivity,” French says. To
compensate, the measurement aircraft
carried a W-band radar system, which
uses shorter wavelengths that provide
greater measurement sensitivities at
ranges of 1 to 2 kilometers.
Shortly after seeding, the groundbased radars detected discrete bands of
increased radar reflectivity downwind
of the seeding flights, indicating ice crystals were forming in the clouds. Outside
these bands, the measurement aircraft
detected tiny liquid water droplets but
no ice crystals.
When the aircraft passed through
developing bands of high radar reflectivity, it detected significantly lower levels
of liquid water than in areas outside the
bands. The team also found evidence of
ice crystals up to 1 millimeter in diameter — evidence that water droplets were
turning into ice crystals. On subsequent
passes through these bands, they observed
ice crystals as large as 8 millimeters across.
Eventually, the bands of increased
reflectivity stretched from the clouds
to ground level, indicating that the ice
crystals were falling as snow.
“This study provides the best evidence so far about what happens after
silver iodide particles are introduced into
clouds,” says Daniel Rosenfeld, an atmospheric scientist at Hebrew University
of Jerusalem, who was not involved in
the study. That’s important, Rosenfeld
says, because without concrete evidence of
the mechanisms involved, there has been
“much skepticism and a lack of funding
from governments to study cloud seeding.”
“We haven’t yet shown whether cloud
seeding leads to increased snowfall [on
A “Doppler on Wheels” truck, equipped
with X-band radar, atop Packer John Mountain in the Salmon River Range in central
Idaho tracks the formation of ice particles
during cloud seeding experiments.
Credit: Josh Aikens
TEKIȦȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
News
a broader scale],” French says. But this
study will help answer that question, he
says, because it provides a methodology
to gather more quantitative data about the
different stages of cloud seeding, which
can be used to develop better numerical models of the process. “Ultimately,
we could use these models to assess the
broader question of whether we can meaningfully impact rain or snowfall over the
course of a season within an area using
cloud seeding.”
Rosenfeld agrees, but points out
that the physical results of the seeding experiments in this study may not
apply everywhere. “The atmospheric
conditions in southwestern Idaho are
(PMQEXI[EVQMRKQEOIWJSVLE^MIV'IMNMRK
'IMNMRK LEW FIIR IRKYPJIH F] TIVWMWXIRX LE^I IZIRXW 5-*W JSV ]IEVW
but now researchers found that along with pollution emissions, unusual
atmospheric circulation patterns set up by climate warming may be to
blame. Researchers found that warmer sea-surface temperatures in the
Pacific spur weakened East Asian winter monsoons and a northward shift
of the East Asian Jet Stream in the upper troposphere, encouraging PHEs
to settle over Beijing.
5IMIXEP&XQSWTLIVMG(LIQMWXV]ERH5L]WMGW2EVGLȶȉȦȁ
somewhat distinct, as shown by the
relatively small numbers of droplets
and crystals in the clouds before seeding,” he says. “Other areas, those with
urban settlements or more industry,
for example, will have more aerosols
in the atmosphere, some of which may
[already] act to create ice as cloud seeding does.” Therefore, it remains unclear
how effective cloud seeding efforts
would be in those areas.
&HMX]EVYT(LEOVEZSVX]
Oldest human remains outside Africa found in Israel
T
he recent discovery of a jawbone
belonging to Homo sapiens, and
associated stone tools, in Israel
may push back the timing of the
earliest human migration out of Africa by
as much as 50,000 years.
To date, the oldest human remains
found outside of Africa are thought to
be 90,000 to 120,000 years old. But a set
of eight teeth encased in a partial upper
jawbone found in Misliya Cave in northern
Israel has been found, using three independent dating methods, to be between
177,000 and 194,000 years old. Stone tools
located nearby were carved using the
sophisticated Levallois technique, a distinctive style of flint knapping, suggesting
that the emergence of the technology may
coincide with the earliest human migrations
out of Africa.
Decades of excavations at Misliya Cave,
near Mount Carmel, Israel, have turned up
early-human evidence — such as tools, animal bones and fire rings — suggesting more
than 100,000 years of human occupation at
the site. But the jawbone represents the first
human remains found there, the team led by
Israel Hershkovitz of Tel Aviv University
wrote in Science.
The revised timeframe, with humans
leaving Africa at least 55,000 years earlier
than previously thought, is consistent with
recent genetic studies that suggest modern
humans might have migrated from Africa as
early as 220,000 years ago. It also dovetails
with evidence uncovered in China and
across western Asia that H. sapiens may
have overlapped — and interbred — with
Neanderthals and other hominin species
for much longer than previously thought,
according to a perspective written by Chris
Stringer, a paleoanthropologist at the Natural History Museum in London, in the same
issue of Science.
“Misliya is an exciting discovery,” said
study co-author Rolf Quam of Binghamton
University in New York, in a statement. “It
provides the clearest evidence yet that our
ancestors first migrated out of Africa much
earlier than we previously believed. It also
means that modern humans were poten-
tially meeting and interacting during a
longer period of time with other archaic
human groups, providing more opportunity for cultural and biological exchanges.”
2EV](ETIVXSR2SVXSR
Close-up view of the human jawbone fossil found in Misliya Cave in northern Israel,
showing details of the crown topography and dental features.
Credit: both: Rolf Quam/Binghamton University
TEKIȦȍ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
News
;LMGL[EVQ[EXIVWFSSWXIH-YVVMGERI-EVZI]$
L
ast August, Hurricane Harvey
walloped Texas, dropping more
than 100 centimeters of rain on
Houston and nearby areas, and
causing more than $125 billion in damage. But almost nobody saw it coming.
In the days before Harvey made landfall
60 kilometers east of Corpus Christi,
the tropical storm barely registered as a
threat, but within 30 hours it escalated
from a tropical storm into a Category 4
hurricane. Using data collected before and
during the storm, scientists are piecing
together how Harvey became so ferocious
so fast, an effort that could help scientists
better predict which future storms might
have similarly rapid intensifications.
Two weeks before Harvey hit,
researchers from Texas A&M University conducted a hydrographic survey of
the shallow waters of the Texas Bight
just off the coast near Corpus Christi.
“This was part of an unrelated project to
study water quality, but it gave us some
very interesting and valuable data about
how much heat was available in coastal
waters leading up to the storm,” says
Henry Potter, an oceanographer at Texas
A&M, who presented his findings at the
2018 Ocean Sciences meeting in February
in Portland, Ore.
The team found that the average water
temperature across the bight in August
was 28.3 degrees Celsius, 1.8 degrees
warmer than it had been in June, when
the prior survey was conducted. “That’s
essentially bathwater, all the way down
to the bottom,” Potter says.
Ocean temperatures are usually estimated from satellite data, which has
upsides and downsides, Potter says. Such
measurements tell you how much heat
is in a body of water, “but you don’t
know where it’s located in the water
column,” he says. “The benefit of [the
hydrographic] dataset is that we knew
exactly where the heat was and how
much was there, which gave us some
really good information about the heat
available to drive Harvey.”
In general, warmer water begets
stronger hurricanes. “If the water temperature is above 26 degrees Celsius,
then it’s probably warmer than the atmosphere, which means that heat goes from
the ocean into the atmosphere … which
drives the hurricane,” Potter says. Despite
the high water temperatures in the bight
prior to Harvey, the calculated values of
Tropical Cyclone Heat Potential (TCHP)
— a metric used to predict whether a tropical storm will intensify into a hurricane
— weren’t notably strong. Regions with
a TCHP above 90 kilojoules per square
centimeter (kJ/cm2) have previously
been associated with rapidly intensifying
storms, but the TCHP of the Texas Bight
was only about 35 kJ/cm2. This suggests
that “the TCHP may not be a good metric
to use in shallow water, like [off] the coast
of Texas,” Potter says.
But the heat that drove Harvey to
intensify so quickly could have also come
Storm Track Wind Speed (m sȦ)
ȉ
Ȧȉ ȶȉ ȴȉ ȏȉ ȍȉ
Texas
Bight
&YKYWXȦȁȶȉȦȮ
Ocean Heat
Content (kJ cmȶ)
Ȧȶȉ
(EXIKSV]ȏ
Ȧȉȉ
(EXIKSV]ȴ
ȁȉ
(EXIKSV]ȶ
(EXIKSV]Ȧ
Harvey rapidly intensified from a tropical
WXSVQXSE(EXIKSV]ȏLYVVMGERIEWMXQSZIH
across the Gulf of Mexico. Warmer colors indicate higher ocean temperatures in the Gulf,
and higher wind speeds on the storm track.
Credit: K. Cantner, AGI , with data from UODL and
Potter et al.
Ȱȉ
ȏȉ
ȶȉ
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from farther offshore, says Nick Shay,
an oceanographer at the University of
Miami who was not involved in the new
study. “Harvey may have gotten a little
jolt over the warm slug of coastal waters,
but, by and large, it got most of its warm
water boost earlier over a big ‘warm-core’
eddy that was moving across the Gulf.”
This pattern is not unique to Harvey,
he says. “We’ve seen this interaction many
times. This warm-core eddy is often
present in the Gulf during the summer
months, throughout the hurricane season, and when storms encounter it, they
sometimes explode.”
But even though this pattern has been
seen in previous hurricanes — such as Opal
in 1995, which escalated from a Category
1 to a Category 4 in less than 14 hours
— models still struggle to take the warm
Gulf eddy into account when predicting
which storms will escalate. “Our predictive
models are still failing to detect when rapid
intensification may kick in,” Shay says. “A
better understanding of what triggers the
onset of rapid intensification is crucial for
hurricane research. Coping with rapidly
intensifying storms represents a real challenge for emergency managers and local
and state governments.”
Scientists only have detailed data coverage — gathered from instrumented
probes deployed from hurricane hunting
aircraft and ships — during the period
that Harvey escalated from a Category 3
to a Category 4. “A lot of funding goes
into making models, but we need good
data to put into those models,” he says.
During future storms, deploying more
expendable probes, gathering in situ data
from floats and buoys, as well as increasing monitoring from satellites may help
give scientists the data they need to more
accurately predict whether a relatively
benign tropical storm will grow into
a dangerous hurricane. “This type of
rapidly intensifying storm track could
certainly be a repeatable event, especially
in the high summer heat of the Gulf hurricane season,” Potter says.
TEKIȦȰ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
2EV](ETIVXSR2SVXSR
News
Taking the
surprise out of
sneaker waves
S
ince 2005, more than two dozen
confirmed fatalities in California
and Oregon have been caused
by so-called sneaker waves,
which surge far ashore with little warning, sometimes catching beachgoers by
surprise. Most beaches in the Pacific
Northwest and California have posted
signs warning visitors of the hazard, but
few scientific studies have been done on
sneaker waves and, currently, there is no
consensus on their definition or origin. A
new incident database is helping clarify
where and when sneaker waves are most
likely to occur, an important step toward
creating better warning systems.
“Here in Oregon, all the beaches have
signs warning of sneaker waves, but
when you search for scientific studies,
the only information you typically find
are newspaper stories of tragic events,”
says Gabriel García Medina, a coastal
engineer at Oregon State University
(OSU), who is developing the database
and who presented related research at
the Ocean Sciences meeting in Portland,
Ore., in February. Sneaker waves tend
to make the news only when somebody is swept out to sea. “That means
reports are very biased toward events
where somebody is hurt or killed and
somebody else was there to witness the
event,” he says.
Unexpected wave incidents also occur
in Southern California and on the East
and Gulf coasts. But the warmer water
and calmer wave and rip current conditions that prevail along those coasts,
relative to the U.S. West Coast, mean
those incidents are less likely to end in
tragedy. “From the middle of California
all the way up into Canada, getting swept
into the water can be life-threatening,”
says Troy Nicolini, a meteorologist with
the National Weather Service based in
Eureka, Calif., who was not involved
in the research presented at the Ocean
Most beaches in the Pacific Northwest and Northern California have signs warning
beachgoers of sneaker waves.
Credit: )EZI]RMR(('=ȶȉ
Sciences meeting but has collaborated
with García Medina and his colleagues
on related research.
“There are many reasons why people
get in trouble in the coastal zone,” Nicolini
says, which can make discerning sneaker
events difficult. “It can be hard to separate a rough wave event or a cold-water
drowning from a sneaker wave event”
without eyewitness reports, he says.
García Medina and his colleagues
began their study by defining a sneaker
wave as “a wave event when somebody
thought to be in a safe zone was caught
off guard.” They then characterized
beaches and regions where sneaker waves
are more likely to occur by performing threshold analyses for various beach
settings to determine the likelihood of
anomalous waves reaching beachgoers.
They also sought to identify the physical
controls on large wave run-ups, such
as beach topography and the existence
of protective structures such as jetties.
Sneaker waves also occur on beaches
with no witnesses, of course, but without cameras or monitoring equipment,
they’re very difficult to identify.
“I’m very excited to see the OSU team
bring this amount of rigor to the study
of sneaker waves,” Nicolini says. “It has
always been a struggle to connect the
dots with these kinds of events. We have
hypotheses about why they occur when
and where they do, but very little data
with which to test those hypotheses.”
The team identified 27 cases in Northern California and Oregon in which
witnesses confirmed that victims standing
on beaches were struck by surprisingly
large waves. The researchers also determined that sneaker wave events occurred
over a wide range of wave heights —
emerging not only from stormy seas but
sometimes also from calm seas — but that
most were associated with long-period
swells arriving from distant storms. For
the majority of the fatalities, simulated
wave run-ups on the particular beaches
where accidents occurred correctly predicted that the water level could reach
victims’ locations, suggesting that an
accurate warning system could be created
for individual beaches.
“A warning system would have
to operate on a local basis, starting at
beaches that have had multiple incidences
of sneaker waves,” García Medina says.
“We’d be looking to predict the likelihood
of a wave overtopping a beach, berm or
jetty, given certain weather and wave
patterns, which could be monitored using
buoys or cameras. That might be much
more effective than just issuing blanket
warnings for entire coastlines.”
TEKIȦȮ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
2EV](ETIVXSR2SVXSR
News
Airport earthquakes continued after injection ended
Air
po
Dallas Fort
Worth Airport
lt
North injection well
is used for wastewater injection and storage. Throughout recorded history, the
northeast-southwest trending normal fault
system that runs through these layers was
static. But injections of wastewater into
these formations changed the pore pressures in the rocks, and seven months after
the first injections, seismometers detected
earthquakes along the fault system.
Paul Ogwari of Southern Methodist University in Dallas and colleagues
analyzed seismic data collected between
2008 and 2015. Using additional seismic
stations, the team tripled the known earthquake catalog in the region, producing
the most complete dataset yet. In total,
they found more than 400 induced quakes
between magnitude 0.5 and 3.4, the largest
of which were felt by people in the heavily
populated Dallas-Fort Worth area.
The analysis, published in the Journal of
Geophysical Research: Solid Earth, reveals
curious patterns in the seismic record.
The frequency of the
quakes decreased since
injection stopped —
from dozens of events
per month in 2008
and 2009 to a handful a month in recent
years — but the magnitudes have remained
consistent. “We generally expect the biggest
events early on in the
rt
Fa
u
S
ince Oct. 31, 2008, when seismic activity was first detected,
hundreds of earthquakes smaller
than magnitude 3.4 have peppered
a fault zone that partly underlies the Dallas/Fort Worth International Airport
(DFW) in north-central Texas. After the
quakes were linked to the subsurface disposal of wastewater fluids from oil and
gas operations in wells located within a
kilometer of the initial quakes, wastewater
injections into those wells were halted
in August 2009. A new study finds that
quakes near the airport continued for years
after the wells were shut down, suggesting
that halting wastewater injection may not
immediately stop induced seismicity.
Before Halloween 2008, the Fort
Worth Basin had no historical record
of seismicity. The region is underlain
by the Barnett Shale, a major source of
natural gas, as well as the Ellenburger
Formation, a granite basement layer that
Seismicity induced by
wastewater injection
around the Dallas/
Fort Worth International Airport did not
cease when injec-
South injection well
XMSRcWXSTTIH8LIWSPMH
red line delineates the
ȉ
Ȧ
ȶ
ȴ
kilometers
Number of
earthquakes
in cluster
Ȧ
Ȧȉ
ȍȉ
Airport Fault, while the
dashed red line marks
a cross section in a new
pore pressure study.
Credit: K. Cantner, AGI
modified from Ogwari et
EPȶȉȦȁ
sequence, followed by some tapering of the
size of the earthquakes, but instead, this
fault continues to produce magnitudes up
to 3.4 years after injections ceased,” Ogwari
says. The physical properties underlying
this pattern remain elusive, but Ogwari
suspects there is something to be learned
about how faults heal over time, or do not,
after wastewater injections.
The induced quakes at DFW offer a
unique opportunity to study how fluids affect the friction along faults, says
Matthew Weingarten, a geophysicist
at Stanford University who was not
involved in the new study. “The numerical modeling presented by [the Ogwari]
study is key to understanding how fluid
pressures and stress changes are translated onto faults in ways that make them
more likely to fail.”
To better understand the stress
changes along the 6-kilometer-long
Airport Fault, Ogwari and colleagues
modeled the location and timing of
increasing pore pressures in the rock as
injected wastewater infiltrated the fault
zone. They found that pore pressures
increased along the fault at varying rates,
depending on factors such as the local
,YPJHIEH^SRI[MPP
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Despite agricultural management
efforts in recent decades to limit
nutrient runoff into the Gulf of
Mexico — where excess nitrogen
feeds phytoplankton blooms that
later decompose and deplete
S\]KIR ƴ ȶȉȦȮ WE[ XLI FMKKIWX
dead zone ever recorded. A new
study now estimates that even if
all nitrogen runoff were stopped
today — a scenario the authors
contend is not only “unrealistic,
but also inherently unsustainable” — the dead zone would take
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TEKIȦȁ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
News
permeability of the rocks and the volume
and location of the injections — information that sheds light on why the quakes
have continued for so long. Ultimately,
further permeability modeling may help
identify the types of geologic settings
that may be more likely to cause induced
seismicity along faults, Weingarten says.
Ogwari and his team studied the
period from 2008 through 2015, using
a combination of seismic stations that
operated near the airport between 2008
and 2010, and U.S. Geological Survey
instruments located as far away as
245 kilometers that recorded seismicity over the whole period studied. The
quakes have continued since the end of
the study period, and “we don’t know
how long the earthquakes will continue,”
Ogwari says. “Southern Methodist University and TexNet — the Texas Seismic
Monitoring Program — will continue to
monitor both the DFW Airport Fault
and other faults in the basin for ongoing seismicity.”
Knowing the area’s baseline conditions
will help researchers understand how
seismicity may be initiated or altered by
injection. Future studies may benefit from
installing seismic stations before wastewater injections start so that scientists can
collect data on the natural activity rate over
the entire sequence of induced earthquakes.
“In many cases, we miss the beginning of
the sequence, since many of these induced
quakes occur in places that don’t usually see
seismicity and aren’t monitored,” Ogwari
says. “There’s more to the sequence than
just the quakes that are strong enough to
be felt by people or detected by distant
seismic networks.”
2EV](ETIVXSR2SVXSR
Skate eggs found on hydrothermal vents
I
n July 2016, a team of scientists
came upon a surprise 1,660 meters
beneath the ocean’s surface near
the Galápagos Islands: a clutch of
yellow eggs, laid by a Pacific white skate,
a cousin of rays and sharks. It was not
the eggs themselves that surprised the
team, but where they were found: near
a volcanic hydrothermal vent. The large
number of eggs at the site led the team to
suggest that the skate was likely using the
vent’s heat to incubate the eggs.
The egg cases were discovered by
researchers piloting Ocean Exploration
Trust’s remotely operated vehicle (ROV)
Hercules while on a cruise to help Ecuador’s government define the borders of
Galápagos National Park.
On a 15-hour dive to the Galápagos
spreading center — a volcanic rift that
divides the Cocos Plate to the north and
the Nazca Plate to the south — Hercules “flew” through seafloor canyons and
encountered a variety of sea life, such as
alvinellid worms, which live in extremely
hot waters like those next to hydrothermal
vents, and bioluminescent shrimp glowing
in the darkness. Then, with the scientists
observing via video monitors on the surface ship, the eggs appeared near the ROV.
“No one was expecting to see these
eggs,” says Brennan Phillips, an oceanographer at the University of Rhode Island
(URI) and a co-author of a new Scientific
Reports study describing the find. The
discovery of egg cases purposefully laid
next to a hydrothermal vent is a first.
Researchers found that water temperatures near the eggs were, on average,
hotter than the surrounding waters. “The
background temperature was about
2.76 degrees Celsius,” Phillips says.
Some eggs were in waters of average
temperature, but most were in warmer
water, around 2.8 degrees Celsius, with
the highest temperatures surrounding
eggs being about 3.6 degrees Celsius. A
temperature increase of only about 0.1 or
0.2 degrees Celsius is enough to decrease
incubation times by months or even years,
Phillips says.
Moreover, the fact that most of the
157 eggs the researchers counted were
in relatively warm waters suggests the
placement was intentional egg-laying
behavior. “There seems to be some sort
of optimal temperature that they were
aiming for,” he says.
“We’ve never seen organisms using
vents — because of their temperatures
— as nurseries,” says Roxanne Beinart, a deep-sea biologist also at URI but
who was not involved in the discovery.
“That’s the new and exciting thing about
this discovery,” Beinart says. So far, the
behavior is unique among ocean animals,
although some terrestrial animals — like
some modern birds — are known to use
geothermal heat to incubate their eggs,
and some extinct sauropod dinosaurs
are thought to have also displayed this
behavior. Beinart adds that experiments
on the relationship between temperature
and the length of time it takes skate
embryos to develop could help solidify
the validity of the hydrothermal nursery hypothesis.
Phillips plans to investigate how
other large marine species interact with
submarine volcanic environments. For
example, sharks — one of the longest-lived fish lineages, with origins
extending back to the Paleozoic — may
use rift environments to their advantage,
he says.
Lucas Joel
A skate egg case found near hydrothermal
vents in the Galápagos spreading center.
Credit: Ocean Exploration Trust
TEKIȦȟ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
News
Solar eclipse
mimics conditions
SRc2EVW
W
hat does a total solar
eclipse here on Earth
have to do with studying life on Mars? The
answer lies nearly 25 kilometers above
Earth’s surface in the stratosphere,
where the August 2017 eclipse offered
researchers a rare opportunity to mimic
conditions on the Red Planet.
“The stratosphere is similar in many
ways to [the atmosphere at] Mars’ surface,”
Angela Des Jardins, director of the NASA
Eclipse Ballooning Project, said at a press
conference at the fall meeting of the American Geophysical Union last December.
NASA researchers and their collaborators have previously conducted
earthbound experiments to predict what
kind of microscopic life could potentially
grow in the inhospitable conditions on
Mars, and which microorganisms could
potentially hitchhike on spacecraft and
colonize Mars.
Des Jardins described typical conditions in our stratosphere that are similar
to Mars’ atmosphere, including low temperatures, pressures and water contents.
A key difference between Mars and the
stratosphere, however, is the amount of
ultraviolet (UV) radiation and overall
sunlight each receives.
“Light coming from the sun is very
complex, making it difficult to replicate,”
says David Smith, deputy branch chief
of NASA’s Space Biosciences Research
Branch and a collaborator on the Eclipse
Ballooning Project. “The attenuated sunlight during a solar eclipse offers UV
conditions that are likely closer to what
is expected on Mars.”
To take advantage of the conditions
provided by the 2017 total solar eclipse,
NASA worked with dozens of citizen
science teams across the country. The
teams, comprising mostly high school and
college students, launched a constellation
of balloons along the eclipse’s path of
Teams of citizen scientists launched balloons carrying bacteria samples into the stratosphere during the solar eclipse, when some conditions approximated those on the surface
of Mars. Pictured here is an earlier test launch by a team from Montana State University.
Credit: Montana State University
totality, which in the U.S. stretched from
Oregon to South Carolina. Thirty-four of
these balloons included a thin aluminum
strip that contained the Paenibacillus xerothermodurans bacterium.
This common soil bacterium was
selected for a number of reasons: it forms
spores, it can survive hot and dry extremes,
and it is harmless to humans and the environment. Most importantly, numerous
similar bacteria from the Paenibacillus
genus have been swabbed off the floors of
meticulously sterilized NASA clean rooms
and even off sterilized pieces of spacecraft,
indicating the bacteria’s knack for surviving incredibly harsh treatment.
“It’s important to understand the edge
of habitability,” Smith says, “both how
life as we know it lives on the margins
and survivability of [bacterial] hitchhikers
[during space travel].” This especially resilient bacterium thus makes a good study
subject in experiments seeking to answer
both questions, he says.
Researchers on the project are currently
measuring the survival of P. xerothermodurans after exposure to Mars-like conditions
on the balloons, and sequencing their
genomes for potential mutations brought
on by environmental stress. Identifying
mutations could provide insights into
which genes in these and other bacteria allow them to survive at the edge
of habitability.
Findings from this project will be
combined with previous and ongoing
experiments. These and other bacteria
and fungi are regularly sent up on balloons,
treated with hostile compounds present on
Mars in the lab, and exposed to microgravity and the stresses of space for months at
a time on the International Space Station.
Such research can also help medical
specialists understand how astronaut
microbiomes might be affected by
prolonged spaceflight and anticipate how
bacteria could affect the first humans to
set foot on the Red Planet.
The balloon project offered a rare
and relatively inexpensive opportunity
to engage citizen and student scientists
in a large, seldom-possible research
opportunity, Smith says. “Hopefully,
we hooked a few people,” he adds.
“The next generation is going to
be essential for answering these
questions” about habitability on Mars.
/SWL0REGOIVX
7EVIQMRIVEPZEXIVMXI
JSYRHMRTPERXW
A rare and unstable form of calcium
carbonate, vaterite, has been found
in an unlikely place: alpine plants.
A new study using cryo-scanning
electron microscopes shows that
some saxifrage plants — known as
rockfoils — secrete the rare mineral
out of “chalk glands” in their leaves.
;MKLXQERIXEP+PSVE&TVMPȶȉȦȁ
TEKIȶȉ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
News
&VIHMEXSQWXVMKKIVMRKWYFQEVMRIPERHWPMHIW$
F
ar beneath the ocean’s surface,
puzzling deposits from huge submarine landslides can be found
amid expanses of nearly flat
ocean floor. Without steep terrain, what
causes these megaslides? In a new study,
scientists who delved into deep-sea drilling records report a potential trigger for
one such slide off the coast of northwest
Africa: diatom ooze.
Submarine landslides are found around
the planet. With little to impede their
flow and buoyed by seawater, they can
reach almost unfathomable scales and
travel great distances. For instance, a
giant landslide off the coast of Norway
that occurred about 8,100 years ago carried more than 3,300 cubic kilometers of
sediment. By comparison, the eruption
of Mount St. Helens displaced 3 cubic
kilometers of material.
Scientists have known for some time
that the largest submarine slides actually occur in gently sloping areas along
continental slopes, where inclines are
less than 3 degrees. “When looking at
maps of the seafloor, you see flat, smooth
surfaces that look like they were displaced as an entire package,” says Morelia
Urlaub, a researcher at GEOMAR in
Germany and lead author of the new
study in Geology.
To delve into what might trigger such
huge slides to occur on gentle underwater
slopes, Urlaub and her colleagues studied
the large Cap Blanc slide off the coast of
Mauritania, where the seabed is smooth
and the slope is just 2.8 degrees. The slide
has headwalls as tall as 100 meters, where
it detached from the adjacent ocean floor.
The team’s supposition was that a weak
layer of buried sediment lost strength,
causing the whole package of marine
sediments to slide downward. Although
this hypothesis of submarine landslide
triggering is widely considered plausible,
testing it has proved difficult. “The problem is that, because the layer is so weak, it
most likely vanished with the landslide,”
Urlaub says, so the strategy was to study
stable sediments from an area next to or
upslope of the landslide.
Collecting fresh samples — from
depths up to 300 meters below the ocean
floor — would have required a costly
drilling expedition. Luckily, Urlaub
found that, in the 1980s, the Ocean Drilling Program had drilled a deep sediment
core and taken an accompanying seismic
survey at a site just north of Cap Blanc.
This data allowed the team to analyze
sediment stacks nearly identical to what
failed in the Cap Blanc slide, along with
what they saw in the seismic reflections,
to find potentially weak layers.
In the sediment core, the team found a
possible culprit for the Cap Blanc slide: a
layer of diatom ooze about 10 meters thick.
Diatoms are microscopic phytoplankton
that excrete shells of silica. Urlaub says
that, in this area, there must have been
a prolonged period of time when phytoplankton bloomed
and subsequently
died, raining down
shells on the seafloor. Eventually,
this layer of diatoms
was buried by other
marine sediments.
“Diatom [shells]
are hollow and
quite stiff, and
sediment made of
diatom shells have
A scanning electron microscope image of marine diatom mud.
high porosity,”
Credit: Gauvain Wiemer/MARUM/University of Bremen
Urlaub says, adding
that when the shells are eventually
crushed under the weight of overlying
sediment, a layer of water-saturated diatom ooze can form. When a waterlogged
diatom layer is quickly compacted, the
water must drain somewhere, she says,
but impermeable clay layers adjacent to a
diatom layer can trap the water, creating
the ooze. This, in turn, may decrease the
stability of an entire sediment package
and trigger a landslide.
“This concept of weak layers has been
hypothesized, but very rarely realized
for submarine landslides,” says David
Mosher, senior research scientist at Natural Resources Canada. Mosher says
that such diatom oozes don’t trigger all
submarine slides, but Urlaub and her
team “make a compelling case that, in
this instance, the diatoms are the cause.”
Researchers previously suggested that
slides like the one off Mauritania were
triggered by earthquakes, but an earthquake “would have to be really, really
strong” to produce a slide thousands of
cubic kilometers in size, he says. Weak
sediment layers that extend over vast
areas of seafloor seem to be a much
more likely scenario, in which “only one
area has to fail and then [that] triggers
the rest.”
Understanding how these massive
submarine landslides occur has implications for both science and society. “If you
know something about the stratigraphy
in a certain environment, then you can
say something about its risk,” Mosher
says. Predicting which areas may be susceptible to large slides, and the potential
tsunamis they might cause, can help
communities and governments prepare
for such events.
Although the depth of the weak layer
in the sediments at Cap Blanc has now
been narrowed down, “we cannot really
pinpoint exactly where the failure took
place: Was it in the diatom ooze, was it
in the clay, or was it at the interface of
the two?” Urlaub says. “We are not there
yet — we need to do some more work.”
TEKIȶȦ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Sarah Derouin
News
87&55.8Ȧ
system hosts
seven “Earth-like”
planets
I
n 2017, astronomers discovered
seven planets orbiting a star dubbed
TRAPPIST-1, a faint red dwarf
40 light-years from Earth and only
9 percent as bright as our sun. The
Earth-like qualities of these planets made
headlines: they are of similar sizes to
our planet, and their orbits fall within
TRAPPIST-1’s habitable zone — two
characteristics that scientists think are
important for life to exist on a planet.
Researchers now report that the TRAPPIST-1 planets have even more traits
in common with Earth: they are likely
rocky, and they may have surface water
that exists as liquid, ice and vapor.
Using data from the Spitzer and Kepler
space telescopes, a team of scientists, led by
astrophysicist Simon Grimm of the University of Bern in Switzerland, calculated
the planets’ masses and densities. Knowing
these two characteristics, Grimm explains,
allows researchers to interpret what the
interior structure of a planet is like. “Is it
a gas planet or is it a rocky planet with a
solid crust?” Grimm asks. “The most interesting fact about the TRAPPIST-1 planets
is that all of the planets are similar to the
Earth,” he says.
The planets are far too distant to see
directly, even with the space telescopes.
So, researchers study them by measuring,
for instance, how much light the planets
block as they pass in front of their host
star. “The amount of light [a planet]
blocks is proportional to the area of the
planet,” says Ben Moore, an astrophysicist
at the University of Zürich in Switzerland
who was not involved in the research.
In a new study, published in Astronomy
& Astrophysics, Grimm’s team used the
“transit timing method,” which, Moore
explains, accounts for how the gravity
of each planet can alter the orbits of the
other planets. “There are slight changes in
&RMPPYWXVEXMSRSJXLIWIZIR87&55.8ȦTPERIXW[LMGLEVIEPPVSYKLP]*EVXLWM^IH87&55.8ȦIJSYVXLJVSQXLIPIJXMWGSRWMHIVIHXLIQSWX*EVXLPMOISZIVEPP
Credit: NASA/JPL-Caltech
the times that they pass [in front] of the
star, because their orbits aren’t exactly as
they would be if they were alone,” he says.
Once the team had the data on the planets’
orbital variations, they used a computer
model to estimate the planetary masses
that best matched their orbital observations. The team determined “the masses,
and therefore the densities, to an accuracy
of 5 percent, which is pretty impressive for
Earth-like planets 40 light-years away,”
Moore says.
All of the planets, from TRAPPIST-1b
(closest to the parent star) through TRAPPIST-1h, are rocky, and each probably
contains a large amount of water, Grimm
says — observations that weren’t available
before this study. Water likely exists in
different states on different TRAPPIST-1
planets because each one — depending
on its distance from the star — receives
more or less energy at its surface from
the star. Grimm says that TRAPPIST-1e
is the most Earth-like: “Planet e is the
most similar in terms of mass, size and
incoming energy flux from the star.” The
planet’s mass is about 77 percent that of
Earth’s, and its radius is about 91 percent.
And because of its distance from its star,
TRAPPIST-1e could very well have liquid
water on its rocky surface.
The farthest planets in the system,
TRAPPIST-1f, g and h, may only have
frozen water on their surfaces, while those
closer to the star, which receive more heat,
likely have atmospheres thick with water
vapor. TRAPPIST-1d, Grimm describes, is
the lightest of the planets, but it is unclear
what state water is likely in on its surface. Such fuzzy details should become
clearer as more powerful telescopes, like
the Extremely Large Telescope in Chile,
come online in the next several years,
Moore says.
It is only a matter of time until it could
be possible to detect telltale signs of life
on other planets — be it in the TRAPPIST-1 system or elsewhere, Moore says.
“I think we’ll know in the next 20 years
if there is life on these worlds.”
Lucas Joel
4PHIWXIZETSVMXI
VIZIEPW*EVXLƶWIEVP]
EXQSWTLIVI
& ȶFMPPMSR]IEVSPH IZETSVMXI
deposit recovered from the Onega
Basin in Karelia, Russia, has given
researchers a window into early
Earth’s ocean and atmospheric
chemistry shortly after the Great
Oxidation Event, extending this
record by almost a billion years.
Researchers found that large
amounts of oxygen were reacting
with sulfur at that time, accumulating in the oceans as sulfates,
which indicates that, after the
initial oxidation event, sustained
oxygen production continued.
'P®XXPIVIXEPGMIRGI2EVGLȶȉȦȁ
TEKIȶȶ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
News
Red Planet Roundup
W
ith two rovers patrolling the surface of Mars, six spacecraft orbiting above it, and scientists here on Earth studying the Red Planet
from afar, new findings are announced often. Here are a few of
the latest updates.
• Mars is thought by many scientists
to have been warm and wet early
in its history, before it became the
chilly, arid planet we know today. But
piecing together the sedimentary
evidence of this watery past is an
ongoing challenge. In a new study
in Planetary and Space Science,
Donald Barker of the University of
Houston and Janok Bhattacharya
of McMaster University in Canada
present a new sequence stratigraphy model for an early, wet Mars
that involves an active water cycle,
including precipitation and runoff. The researchers suggest the
2IWWMRMEREPMRMX](VMWMW2(EWE
terrestrial analogue, and propose
that evaporite, clay and sulfite
deposits amid the northern plains
of Mars, as well as detrital fans,
were progressively produced by the
shrinking of an early ocean, resulting
from the loss of atmosphere and
declining precipitation. “We suggest
that the evolution of similar conditions [as the MSC] on Mars would
have led to the emplacement of
diagnostic sequences of deposits
and regional scale unconformities,
consistent with intermittent resurfacing of the northern plains and the
progressive loss of an early ocean
by the end of the Hesperian Era,” the
researchers wrote.
• A future Mars mission will return
a piece of the Red Planet from
whence it came. Researchers at
NASA’s Jet Propulsion Laboratory in
Pasadena, Calif., plan to use a piece
of Mars meteorite Sayh al UhayQMVȉȉȁJSYRHMR4QERMRȦȟȟȟXS
calibrate the SHERLOC (Scanning
Habitable Environments with Raman
and Luminescence for Organics and
(LIQMGEPW MRWXVYQIRX EFSEVH XLI
2EVWȶȉȶȉVSZIVQMWWMSR[LMGL[MPP
search for biosignatures and cache
rock and soil samples for a later
sample return mission. SHERLOC
will use a laser that can illuminate
rock features as fine as a human
hair and analyze rocks for carbon
compounds. “We’re studying things
on such a fine scale that slight misalignments, caused by changes in
temperature or even the rover settling into sand, can require us to
correct our aim,” said Luther Beegle,
principal investigator for SHERLOC,
in a statement. “By studying how
the instrument sees a fixed target,
we can understand how it will see a
piece of the Martian surface.” Other
calibration targets will include materials that might be used to outfit
humans on future Mars missions,
including spacesuit fabric, gloves
and a helmet visor, which will allow
researchers to test these materials’ performance.
• 2EVW ȶȉȶȉ VSZIV QMWWMSR TPERRIVW
are considering potential landing
sites that have been carved and
sandblasted by wind-driven processes. Such processes create and
move large sand dunes, and can
expose long-buried rock, improving the odds of finding any ancient
organic material that the rock might
contain. Matthew Chojnacki, of
the Lunar and Planetary Laboratory at the University of Arizona,
ERH GSPPIEKYIWc YWIH [MRH QIEsurements collected by previous
rover missions to estimate wind
erosion at each of eight proposed
landing sites, and to determine if
newly exposed rock might be present at each. They focused on three
A Martian meteorite that landed in Oman
will be returned to the Red Planet on
XLI 2EVW ȶȉȶȉ VSZIV [LIVI MX [MPP EGX
as a calibration target, similar to the
one shown here aboard the Curiosity
rover, which includes color references,
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penny and a stairstep-textured pattern
for depth calibration.
Credit: NASA/JPL-Caltech/Malin Space
Science Systems
criteria: the presence of regional
FIHJSVQWPMOIHYRIJMIPHWSVVMTTPIW the regional sand flux, which they
estimated using stereo imagery and
digital elevation models to measure
WERHHITXLW ERHIZMHIRGISJWERH
movement, determined by mapping
geomorphological changes over
time. Their results, published in the
Journal of Geophysical Research:
Planets, suggest the proposed
landing sites at Jezero Crater and
Northeast Syrtis — two of the three
finalist sites announced by NASA
MRȶȉȦȮƴSJJIVIHXLIFIWXGLERGI
for collecting samples of recently
exposed rock.
TEKIȶȴ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Sarah Derouin
Feature
Data-Driven Discovery Reveals Earth’s
2..3,c2.3*7&1
8MQSXL]4PIWSR
F
ueled by advances in computing power and
analytical methods, researchers in a growing number of scientific fields have taken
to mining large datasets to reveal big-picture insights. By tallying the words that appear in a
sampling of a book’s pages, for example, lexicologists
— interested in tracking trends over time in language
or literature — can mathematically predict the total
number of distinct words in the book or, say, the
number of different words containing a certain letter
or certain combinations of letters.
Biologists apply similar techniques to estimate
numbers and distributions of unknown species based
on accumulated observations of known life. Such enumerations are a big part of efforts to illuminate Earth’s
biodiversity, which is important not just in satisfying
curiosity about the full breadth of life’s past and present, but also in applications to improve agriculture
or conservation efforts, study disease pathology and
transmission, and search for useful medicines.
Like biologists searching for undiscovered
species, mineralogists have long sought to fill
in the picture of Earth’s mineralogical diversity
with new finds. In recent years, mineralogists,
teamed with mathematicians and others, have
begun using statistical models and data science
methods traditionally applied to study large datasets
in fields like linguistics, evolutionary biology and
social network analysis. The researchers hope to
reveal previously unseen patterns and clues hidden
in mineralogical databases about Earth’s mineral
diversity, and find undiscovered minerals — an
effort that could enlighten our basic understanding
of how our planet formed and has changed over
billions of years, offer insights about the locations
and largesse of deposits of critical natural resources,
and even unearth information about the histories
of other rocky planets.
Waiting to Be Found
The International Mineralogical Association
(IMA) currently recognizes 5,327 distinct mineral
species. Some, such as the major rock-forming silicates and carbonates, are well known and found in
abundance the world over. But most are documented
based on just a few known occurrences. It’s unlikely
that scientists will stumble across many new finds of
singularly abundant minerals on Earth, but numerous rare minerals are probably yet to be discovered.
“We have a very rich and diverse crust of our
planet,” says Bob Hazen, a mineralogist at the
TEKIȶȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Carnegie Institution for Science in Washington,
D.C. “We’ve explored a lot of it, but there’s a lot that
remains unexplored,” he says. “And what we suspect,
what we know … is that there are a lot of minerals
just waiting to be found,” he says.
In fact, new species continue to be identified frequently. In just the last decade, roughly 1,000 new
minerals have been added to the IMA’s rolls, thanks
mostly to advanced instruments that have allowed
researchers to resolve discrete crystal structures,
often in tiny grains of material, with increasing clarity. Nonetheless, the exploration process,
whether in the field or the lab, still relies heavily
on educated guesswork about where to look — and
on luck. “We’d love to be able to predict: What
are those missing minerals, and where do you go
to find them?” Hazen says. In other words, “how
do we make this an active search rather than just
serendipitous discovery?”
Missing Minerals and How to
Count Them
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less common but still known from many localities. Most minerals,
however, are documented based on just a few known occurrences. Petterdite (pink mineral at bottom left, seen with yellow
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from a single site.
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Considering how long mineral hounds, professional and amateur alike, have been scouring Earth’s
surface, it might be hard to imagine there could be
many minerals left to find. But there is no shortage
of potential mineral compositions or structures,
as demonstrated by the vast range of crystalline
compounds that have been created synthetically.
And there are plenty of reasons why mineral species
might have been previously overlooked.
For example, mineral hunters have historically
been drawn to big, colorful, valuable or otherwise
remarkable specimens. But many minerals do not
fit any of those criteria. Additionally, some minerals
are only stable under a narrow range of pressure and
temperature conditions, or they aren’t stable under
the conditions near Earth’s surface. Bridgmanite, for
example, is perhaps the most abundant mineral on
the planet, constituting the bulk of the lower mantle,
but it is essentially absent from Earth’s surface, and
was only formally recognized in 2014.
“Maybe it’s because they’re small or obscure,
maybe it’s because they’re buried, maybe it’s because
they’re hiding in plain sight and they look like
something else that is familiar, so we just walk right
over them,” Hazen says. Whatever the case, “there
are probably thousands of mineral species that are
simply not yet described, but which exist.”
TEKIȶȍ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
By sampling a book’s pages, lexicologists can mathematically predict the total number of distinct words in
the book, or the number of different words containing
a certain letter or combinations of letters. Mineralogists can use similar modeling to predict the total
number of minerals on Earth, or the total number of
minerals containing certain elements.
Credit: Timothy Oleson
Several years ago, Hazen and his colleagues realized that the large amount of existing information in
databases, such as the University of Arizona-based
RRUFF Project and the Mindat website, which
collects both literature- and crowd-sourced information, could offer clues about the number, nature
and whereabouts of these unknown minerals.
In 2014, Hazen, along with mathematician Grethe
Hystad of Purdue University Northwest and others, began analyzing the hundreds of thousands of
mineral-locality pairings collected in Mindat. Each
report of a given mineral at a specific location in
Mindat represented a single datum, and collectively, the dataset provided a “frequency spectrum”
of Earth’s known minerals, charting the number of
different species known from only one site on the
planet, followed by the number known from two
sites, three sites, and so on. The plot highlighted
the striking disparity between the large number of
rare minerals compared to the relative few found at
many locations.
Hazen recognized that the team’s data resembled
so-called Large Number of Rare Events (LNRE)
distributions described by exponentially decreasing mathematical functions. Such patterns are
seen in the uneven numbers of species in plant
and animal populations, and of different words
in books. Whereas roughly one-fifth of the recognized minerals at the time were known from
only a single site, and one-third from one or two
sites, just 2 percent were known from more than
1,000 sites. “You see kind of the same pattern in
word frequency distribution [in books],” Hystad
says, which tend to contain a large proportion of
infrequently used words compared to relatively few
frequently used words.
In a 2015 study published in Mathematical Geosciences, Hystad, Hazen and Robert Downs of the
University of Arizona applied LNRE modeling to the
mineral-locality dataset from Mindat. After fitting
the data to LNRE functions, they estimated that
Earth’s total inventory of minerals should number
at least 6,394 — or 1,563 more than the 4,831 that
were recognized at the time. It was, Hystad notes, the
first quantitative prediction of Earth’s total mineral
inventory using such a technique.
The researchers also used LNRE modeling to
predict how many missing minerals contain specific elements, which may suggest where to look for
untapped mineral diversity. For instance, in a 2015
study in American Mineralogist, they found that
an estimated 496 sodium-containing minerals —
35 percent of the total predicted number — are likely
undiscovered, while the percentage is somewhat
lower for most other elements, such as silicon (28 percent), aluminum (27 percent), sulfur (18 percent) and
copper (17 percent). The disparity, they suggested, is
probably due in part to anthropogenic sampling biases
against sodium minerals, which are typically nondescript looking and not especially valuable compared
to, say, the colorful crystals of many sulfur and copper
minerals. Some sodium minerals also dissolve easily in
water, making them unstable across much of Earth’s
surface. This sort of observation “illustrates the great
promise of exploiting ever-growing mineral data
resources, coupled with the application of powerful
statistical methods,” the researchers wrote.
But applying the same LNRE models developed for
parsing books to predicting missing mineral populations has its shortcomings, mainly because the types
of data — words on a page versus minerals on Earth
— aren’t exactly analogous. “When you’re looking at a
book, you can see all the words,” Hystad says, so each
word stands an equal chance of being observed. That’s
hardly the case with minerals. In addition, the LNRE
predictions assume that the methods used to observe
the data remain unchanged — a safe assumption for
lexical statistics, but not for mineral exploration.
“The way we discover minerals keeps changing,” Hazen says. Early mineral finds were made
by identifying them in hand samples or under light
microscopes. More recent discoveries have required
researchers “to use X-ray diffraction or an electron
microprobe or a transmission electron microscope
TEKIȶȰ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Number of localities
Number of mineral species-locality pairs
.REȶȉȦȍWXYH]-]WXEHIXEPTPSXXIHXLIJVIUYIRG]WTIGXVYQSJORS[RQMRIVEPWPIJX5SMRXWVITVIWIRXXLIRYQFIVSJHMWXMRGXQMRerals known from a given number of localities, while the curve is a mathematical fit of that data from Large Number of Rare Events
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WTIGMIWƴJVSQERƸEGGYQYPEXMSRGYVZIƹVMKLX&WXLIRYQFIVSJQMRIVEPPSGEPMX]SFWIVZEXMSRWMRGVIEWIWEGGSVHMRKXSXLIXIEQƶW
137*QSHIPMRKXLIRYQFIVSJHMWXMRGXQMRIVEPWSFWIVZIHEPWSVMWIWIZIRXYEPP]TPEXIEYMRKEXȰȴȟȏ
Credit: 0(ERXRIV&,.HEXEJVSQ-]WXEHIXEP2EXLIQEXMGEP,ISWGMIRGIW&YKYWXȶȉȦȍ
— as you get more and more sophisticated techniques, many more minerals become accessible,”
he says, even if fewer people have the means to
find them.
For now, the team is continuing to refine the
models it has worked with so far, as well as to
investigate other approaches to predict mineral
diversity. Currently, Hystad says, the best estimate for the minimum total number of minerals
is about 9,300 — already 3,000 more than their
initial estimate.
“Ultimately, we need to develop our own
mathematics,” Hazen says, which probably means
developing a novel, “composite” LNRE model to
account for the various ways in which minerals
can be observed and discovered. Developing the
complex mathematical functions for such a model
won’t be easy, he says, as this is a “frontier area” in
applied mathematics. But “I think when we do, what
we’ll find is that each time a new technique is discovered, the number of predicted missing minerals
will increase quite dramatically.”
The Social Networks of Minerals
With more than 5,300 known minerals — each
with its own array of physical and chemical traits
— documented from recorded findings from nearly
300,000 localities around the world, there is simply
too much mineralogical data available for the human
mind to handle all at once, Hazen notes. “Understanding how nature works, how Earth works as an
engine of selecting, concentrating, and separating
elements into different rocks and mineral types” is
a problem with too many dimensions, he says. But
if we “let the data show us what the principal trends
are, we’re going to make discoveries we never could
have made before.”
He and his colleagues have recently turned to the
tools of network analysis to help see these trends.
Network analysis combines numerical algorithms
and visualization methods to make large, unwieldy
datasets more digestible. It has been applied in
numerous ways, from studying the structure of
electric power grids to mapping the spread of
disease, although one of the most familiar uses
today is in visualizing, analyzing and predicting
(or suggesting) connections among individuals and
groups in social networks.
Network diagrams can take many forms and
shapes but typically consist of two main features:
points, or nodes, each of which represents a single
entity — a particular mineral, for example — and
connecting lines, or edges, which denote some relationship between two nodes. At their most basic,
these diagrams can be simple and largely qualitative,
as in friend networks or family trees, where connections imply direct relationships — whether by
TEKIȶȮ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
& RIX[SVO HMEKVEQ SJ ȍȁ GLVSQMYQ QMRIVEPW WLS[W XLEX XLI]
segregate based on the manner or environment in which each
predominantly forms. Node sizes are proportional to the number
of localities from which each mineral is known, and the distance
between two connected nodes is proportional to the number of
localities at which the two co-occur. Exceptions to the segregation
rule include some abundant chromium minerals like chromite, as
well as certain hydrothermally formed species, like grimaldiite, which
do co-occur with species from other groups. An interactive version
of this diagram is viewable at https://dtdi.carnegiescience.edu.
Credit: 2SVVMWSRIXEP&QIVMGER2MRIVEPSKMWX&YKYWXȶȉȦȮ
social interaction or genealogy — but little
more. Or they can be made to hold much
more information: Nodes can be different
sizes, shapes and colors based on certain qualities
of whatever it is they represent. Connections,
meanwhile, can be different lengths or weights,
for example, to indicate the duration or status of a
relationship, or perhaps the number of places where
two minerals are known to co-occur.
There is virtually an unlimited number of ways
to view and parse large datasets with network diagrams. Researchers can set up networks to answer
particular questions or, alternatively, if the goal is
more explorative, to search for potential lines of
inquiry. In any case, network analysis “allows us
to look at many variables at once,” says Shaunna
Morrison, a mineralogist also at Carnegie. Compared
to using traditional two- or three-dimensional X-Y
plots or ternary diagrams to study mineral relationships, for example, “we’re able to get a much
fuller picture of what’s going on — mineralogically,
chemically, geologically.”
Morrison, Hazen and their colleagues are still in
the early days of pioneering quantitative network
analysis tools for mineralogy. But in an initial study
published last summer in American Mineralogist,
they concluded that “mineral network analysis, by
combining the potential of big data mineralogy and
accessible visual esthetic, represents a powerful new
method to explore fundamental problems in mineralogy and petrology.”
In the study, led by Morrison, the team used
numerical algorithms to plot network diagrams
and illuminate relationships in various mineral
subsets, again based on data from Mindat. Displaying information about existing minerals in such
diagrams could help direct researchers looking for
unknown minerals or ore deposits, they wrote. In
some diagrams, nodes signified individual minerals,
node sizes reflected the commonness of each, and
the length of connections represented how often
minerals co-exist at the same locations. Accounting
for all of the data simultaneously, the algorithms
iteratively adjust the nodes’ positions to minimize the
volume of the overall diagram while maintaining the
correct relative distances among the different nodes.
A plot of several dozen chromium-bearing minerals, for example, appears something like a deformed
“plus” symbol, the shape resulting from the minerals’
segregation based on the manner or environment in
which each predominantly forms. The observation
that chromium minerals — whether igneous, metamorphic, hydrothermal, etc. — tend to be found
primarily alongside others from their same “paragenetic” group may be intuitive for mineralogists or
geologists, but the diagram nonetheless displays the
overall relationship among dozens of minerals in far
more detail than is possible in simpler diagrams. It
also reveals finer-grained insights, the team noted,
including exceptions to the segregation rule; for
example, some abundant chromium minerals, like
chromite, as well as certain hydrothermally formed
species, do co-occur with many species from other
paragenetic groups.
The researchers also created a pair of networks
that incorporated two different types of nodes (instead
TEKIȶȁ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
3IX[SVOHMEKVEQWSJGSTTIVQMRIVEPWGSPSVJYPRSHIWORS[RXSLEZII\MWXIHMRXLI&VGLIER*SRPIJXERHXLI(IRS^SMG*VEVMKLXWLS[
how copper mineral diversity has grown dramatically through geologic history. Archean copper mineralogy was dominated by copper
WYPJMHIQMRIVEPW MRXLI(IRS^SMGWYPJMHIWEVIWXMPPTVSQMRIRXFYXS\]KIRGSRXEMRMRKKVSYTWPMOIWYPJEXIWGEVFSREXIWERHTLSWTLEXIWLEZI
also proliferated. Black nodes in these “bipartite” diagrams represent regions in which connected copper minerals occur.
Credit: 2SVVMWSRIXEP&QIVMGER2MRIVEPSKMWX&YKYWXȶȉȦȮ
of just one); the nodes signified either a particular
copper-bearing mineral or a locality where copper
minerals are found. One of the networks included
sites and minerals dating to the Archean Eon, while
the other related to the Cenozoic Era. This allowed
the team to compare mineral trends within and
between time periods separated by 2.5 billion years.
They noted, for instance, the dominance of copper
sulfide minerals (containing sulfur but not oxygen)
and shortage of copper sulfate minerals (containing sulfur and oxygen) in the Archean, prior to the
oxygenation of Earth’s atmosphere. In the recent
Cenozoic, from which there is far greater copper
mineral diversity known, sulfides are still prominent
but oxygen-containing groups like sulfates, carbonates
and phosphates have also proliferated, particularly
among the many rare copper minerals.
The observation that minerals that form in
low-oxygen environments versus high-oxygen
environments cluster together is “not entirely surprising,” Hazen says. “What was new and what had
not been described in the network [analysis] literature before is that, embedded in the networks, are
axes that show you compositional trends, temporal
trends and other aspects, including, surprisingly,
things like the hardness of the minerals and the
complexity of their crystal structures … even though
[none] of that information [was used] in creating the
networks,” he says. “We’re finding that … because
we’re working with natural systems that have lots
of structure to them, those structures are reflected
in the topologies, in the geometries, of the networks
in ways that simply haven’t been seen.”
With these data science techniques, “we’re able
to really make mineralogy predictive, instead of just
descriptive,” Morrison says. And, Hazen adds, the
potential value of this transition from description
to prediction is already being demonstrated.
TEKIȶȟ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Mining, Mars and More
In a 2016 study in American Mineralogist,
Hazen and his colleagues used the LNRE models
they’d developed to analyze occurrence data for
the 403 carbon-bearing minerals known at the
time. They predicted that at least an additional
145 carbon minerals have yet to be found, and suggested, based on additional analyses of subgroups
of existing carbon minerals (minerals containing
both carbon and oxygen, or carbon and calcium,
for example), that most of these undiscovered species are likely to be hydrous carbonates. They also
offered several hundred plausible compositions for
the unknown minerals.
Since then, 13 new carbon minerals have been
discovered, six of which are hydrous carbonates, and
two of which were found in samples from a mining
district in the Czech Republic that the team had specifically cited as a likely spot for many undiscovered
species. Furthermore, two of the 13 finds — dubbed
abellaite and parisite-(La) — have compositions the
team specifically proposed. While the team’s 2016
predictions didn’t necessarily lead researchers to these
specific finds, the research shows how the data science
techniques the team is developing could be put to use,
Hazen says. “If you know exactly what to look for, you
have the opportunity to go out and find it.”
The approaches the team is developing may also
be useful in revealing new or underutilized deposits
of existing mineral resources. Morrison is currently
adapting an algorithm known as market basket
Data science techniques could be useful in analyzing
mineral assemblages at established ore deposits,
which could then shed light on where other potentially
valuable deposits are located.
Credit: 5IXIV(VEZIR(('=ȶȉ
&FIPPEMXIPIJXERHTEVMWMXI1EVMKLXFSXLVEVIGEVFSREXIQMRerals, are two of more than a dozen carbon-bearing minerals
newly recognized in the last couple of years.
Credit: PIJX2EXXIS(LMRIPPEXS(('=&ȏȉ VMKLXGSYVXIW]SJ
LEYRREc2SVVMWSR
analysis, which online retailers use to suggest products to shoppers, to take advantage of mineralogical
databases — a step beyond the statistical modeling
and network analysis they’ve done to date.
The algorithm tracks purchases, then “it compares
those purchases to its huge database of customers,
and it can tell you pretty accurately what you might
want to buy, even though sometimes those [products] are seemingly unrelated,” Morrison says. With
respect to minerals, the idea is to be able to look at
known mineral assemblages and give probabilities
for the occurrence of other minerals. For example,
“based on what minerals form here … there’s a
90 percent chance that mineral X is also going to
form here.” It would also work for predicting co-located mineral combinations, she says. “Some mining
companies are probably going to be interested in:
‘Where do I find this combination of three minerals
because that means something economically significant?’ And we’ll be able to make that prediction.”
Hazen says there has already been a lot of interest
in how the research relates to resources and mining.
In late April, the researchers held a workshop at
the Colorado School of Mines to meet with economic geologists and discuss applications in terms of
resource discovery. That followed a 2017 workshop
with the U.S. Geological Survey (USGS), which considered how big data and data science approaches like
theirs could improve resource assessments.
Although USGS isn’t directly involved in mineral exploration, the agency’s Mineral Resources
Program develops publicly accessible assessments of
existing and potential resources. “Of current interest are questions like: Where will we find future
supplies of critical minerals? [And] will increasing
global demand create mineral supply shortages,
which could potentially lead to conflict or protectionism?” says Gilpin Robinson, a geologist at USGS
Eastern Mineral and Environmental Resources
TEKIȴȉ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Science Center in Reston, Va.,
who co-organized the 2017
workshop. “Our resource
assessment projects have to
integrate and evaluate large
amounts of data … so we’re
always looking for methods to
improve our ability to do this,
and to improve the resource
assessment results,” he says.
USGS is still scoping out
how data science techniques could be applied in
its assessments, Robinson says. One potential use
is analyzing patterns in mineral assemblages at
established resource deposits, which could then
shed light on other potentially valuable localities
recorded in Mindat and other databases.
“We are virtually certain there will be new
deposits,” Robinson says, adding that the future
likely lies in locating deeper resources that are still
shallow enough to reach. “The question is how you
find them,” he says, which is where the ability to
mine large datasets with data science might come
in. “It’s kind of like exploring for oil and gas,” he
notes. There’s been speculation in the past that
we’ve found most of the available resources, “but
then people come up with a new idea and find new
places where those deposits are.”
In addition to aiding in mineral discovery and
resource assessments, applying data science methods
in mineralogy may also be useful in the classroom,
where interactive network diagrams loaded with
information about minerals and their relationships
in nature could supplement or replace traditional
teaching tools, Hazen and Morrison say.
And there are uses in planetary science. In a 2017
study in Mathematical Geosciences, Hystad and
others applied LNRE modeling to demonstrate that
Earth’s mineralogy is unique: They calculated that
the probability of exactly duplicating the planet’s
roughly 5,000 known minerals on another rocky
planet is less than one in 10263. In the same study, the
researchers described a way to statistically quantify
how “Earth-like” (a notoriously vague term among
planetary scientists) a planet is based on what we
know about its mineralogy and how it compares
to the frequency distribution of minerals on Earth.
“We’re really interested in understanding the
history of Mars … and if there are any potential biosignatures that we can tease out of the mineralogical
In addition to illuminating mineral diversity on Earth, data
science methods could reveal information about the
mineralogy and history of Mars and other rocky planets.
Credit: NASA/JPL-Caltech/MSSS
relationships that we’re seeing on Earth,” Morrison
says. The proliferation of rare mineral species on
Earth is thought to be tied to the rise of life, so
it’s possible that Earth’s overall LNRE pattern of
mineral distribution is a biosignature. So far, “it
seems, based on the rover data and the meteorite
data, that [Mars] does not have the mineral diversity and this large number of rare species that we
see on Earth,” Morrison says. She notes, however,
that scientists have only studied a tiny portion of the
planet in detail, and that the team’s work applying
data science to look more closely at Mars’ minerals
is just beginning.
“We don’t see this as just a mineralogical approach.
We see this as a data-driven discovery approach
that applies to an incredible range of aspects in the
earth and life sciences,” Hazen says. He notes other
recent collaborations his team has struck up with
paleontologists looking to quantify missing portions of the fossil record, which could impact our
understanding of extinction events or evolutionary
rates, as well as microbial ecologists looking to apply
network analysis to better understand the influence
of environmental factors like local mineralogy and
geochemistry on microbial communities.
The team’s research employing data science is
developing “incredibly fast,” Hazen says. “We’re seeing the beginning of a revolution in the way we
think about scientific discovery, using these large data
resources to see trends, correlations and relationships
that the human mind simply cannot see because they
go way beyond just an X-Y plot.”
Oleson is acting senior editor at EARTH.
TEKIȴȦ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
A photosphere view of a
glacial erratic featured in a virtual
reality geology field trip to Columns of the
Giants in the Sierra Nevada of California.
Credit: Ryan Hollister
+.*1);470 &243, 8-* 5.<*1
Virtual and Augmented Reality Diversify
Geoscience Education
Sarah Derouin
W
eeks after taking his students on
a field trip to the Sierra Nevada,
Ryan Hollister, a high school earth
science teacher in Turlock, Calif.,
led the school hiking club on an afterschool trek to a
stretch of nearby river — the same river they’d seen on
the earlier field trip, in fact, just farther downstream.
On the hike, one of the students walked alongside
Hollister. She and her family are refugees who, after
arriving in the country, were relocated to Turlock.
Curious and always eager to perfect her English,
she started making observations during the trip and
peppering Hollister with questions.
“Look, Mr. Hollister, look at this rock: it’s rounded,” she
noted. “What does that tell you?” he asked. “It’s been
in the river; it’s tumbled. Is this a volcanic rock?” “Why
do you think that?” “Well, look at all the bubbles in it.”
“You got it!” “So, there was a volcano nearby? Where?”
Hollister smiles with pride while recounting the
moment. “She put it all together,” he says. “I really
wanted to get them observing and using their critical thinking skills — talking with each other and
talking with me.” Seeing his student use the skills
and knowledge she had learned on the earlier field
trip was a great moment for Hollister — he knew he
had made an impact, he says.
Group field trips and fieldwork have long
fostered community learning environments in
geology, which can help students expand their individual understanding through information sharing.
Standing near a rock formation, making observations and proposing different hypotheses — perhaps
with a few arm-waving ideas thrown in — is a
time-honored tradition in geology. Discussing and
arguing about how to test those hypotheses can
even reveal new geologic insights and discoveries.
But there was a twist to Hollister’s class field trip:
He didn’t guide his students while standing beside
actual outcrops. Instead, the trip unfolded within
the walls of his classroom. He took his students
TEKIȴȶ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
In this composite photograph
YTTIV PIJX 7]ER -SPPMWXIV WRETW
photos of a glacial erratic (see
STIRMRK MQEKI EX (SPYQRW SJ
the Giants from multiple angles.
The many overlapping images of
all sides of the rock were then
stitched together using specialM^IH WSJX[EVI PS[IV PIJX XS GVIate the three-dimensional photogrammatic image of the boulder,
which students could examine on
their virtual field trip.
Credit: both: Ryan Hollister
Technology in Turlock
on a geologic journey using computers and virtual
reality instead of multi-passenger vans.
Advances in imaging and computing technologies have increased accessibility in the geosciences
in the last few years, with virtual and augmented
reality field trips and digital imagery spurring
innovative teaching and creating more inclusive
access to the wonders of the planet. It is no longer
necessary to wrangle dozens — or hundreds — of
students into vans and lead them through field
sites. Today, whole outcrops can be brought into
the classroom.
Advocates of applying such technologies, particularly virtual and augmented reality, to bring
the field into the classroom say the practice can
open doors to underrepresented students, including those faced with socioeconomic pressures,
logistical complications or disabilities that might
otherwise preclude their participation. These tools
also offer new ways of introducing fieldwork,
allowing students to take their time with the process while also strengthening a diverse science
learning community.
Nestled within California’s
Central Valley, Turlock is a
farming community with an international twist. The city of 70,000
is diverse and has been through
much of its history: In 1930, for
example, 20 percent of the population was Assyrian, hailing
primarily from northwestern Iran.
Following the trend of the
last century, Turlock continues
to welcome newcomers. Since
2011, almost 2,000 refugees from
around the world have made it
their new home. Although many know at least some
English, about 40 percent speak a non-English native
language. Children enroll in public schools where
many students are designated English Language
Learners (ELL), polishing their second language
while they learn multiplication tables and U.S. history. These students eventually make their way to
earth science classes at one of two high schools in
Turlock, where they are likely to have a teacher
named Hollister.
Ryan Hollister and his wife, Laura, are both earth
science teachers, though they work at rival high
schools in Turlock. A few years ago, Ryan started
thinking about how to expand his teaching methods,
inspired by educators he followed on Twitter. They
were sharing examples of photogrammetry and
photospheres, in their classrooms.
Photogrammetry is a photography technique
that captures multiple, high-resolution images of an
object — on scales ranging from a roadside outcrop
to a hand sample — to create a three-dimensional
image so detailed that it can be used to make fine
measurements and observations. Photospheres are
TEKIȴȴ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
-SPPMWXIV GVIEXIH QYPXMTPI WXSTW FPYI QEVOIVW MR
his virtual field trip, just as there would be in a traditional geology field trip. In the simulation, each stop
featured open-ended questions that students had to
answer after exploring the location. Hollister calls the
approach “facilitated learning,” and says it helps his
students think critically about what they’re observing.
Credit: Ryan Hollister
360-degree panoramic images that approximate
standing in one location and looking around in every
direction. Photospheres are widely used in Google
Street View, for example, where they allow users
to view a particular location and look around to see
what is next door or across the street.
The imagery intrigued Ryan. “I put it in the back
of my head for a rainy day, thinking, ‘Oh, that’s pretty
cool,’” he says.
In 2016, when the “Science Friday” radio show
put out a call to educators to create a STEM-themed
(Science, Technology, Engineering and Math),
multimedia-driven lesson that could be used in
classrooms around the country, Ryan wanted to use
In Hollister’s virtual field trip, students were encouraged to sketch and take notes about what they saw at each stop in the virtual
field tour, similar to what they would do in the field.
Credit: Ryan Hollister
TEKIȴȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Taking a cue from computer gaming, Jacqueline Houghton of the University of Leeds in
England and her colleagues created a virtual
field trip of local geologic sites in game form,
complete with animations of landmarks and
wildlife. Houghton included a virtual field
notebook where students can learn relevant
details about the rocks at specific outcrops.
Credit: all: Jacqueline Houghton/Virtual Landscapes
- Geoscience Education in Digital Environments
the photosphere and photogrammetry technologies
he had been eyeing to create a virtual geologic field
trip for his students. He was one of a handful of
educators selected to be a part of the Science Friday
Educator Collaborative.
Laura joined the project and they selected a field
site, Columns of the Giants near Sonora Pass in
the Sierras — a geologic smorgasbord filled with
columnar basalts and glacially polished surfaces. It’s
just a couple of hours upstream from Turlock on
the Stanislaus River, which the school hiking club
had visited. The location was chosen for a purpose:
familiarity and access. “Some of the students have
been up to Sonora Pass and they know that place,”
Laura says. “When they see it’s close to home, they
realize … it’s not some distant place in another part
of the country that they might never see.”
Ryan spent the summer of 2016 photographing the field site. Even after the time-consuming
field photography was done, learning the software
programs to create the imagery took many nights
and weekends during the school year. Ryan edited
and stitched together the photos to create
imagery for six separate “field stops” within
the virtual tour of Columns of the Giants.
The technology and methods take some
expertise to utilize, Ryan says. “It’s not as
plug and play as it could be,” though he adds
that, once mastered, creating high-resolution images for virtual reality applications
is relatively quick.
He created both photogrammetric and photospheric images of the field site: photogrammetry for
stationary objects like glacial erratics or outcrops,
and photospheres at each “stop” to allow students
to see their surroundings in 360 degrees.
Along with imagery at each field trip stop and outcrop, Hollister produced an accompanying field guide
to help teach students about what they’re viewing. “It’s
facilitated learning,” he says, adding that the field guide
and associated questions help students research details
they need to know to uncover the geologic history
of the area. The virtual field trip to Columns of the
Giants is free and available through Science Friday.
Gaming Geology
Creating a virtual field trip with photogrammetric and photospheric imagery is one way to take
participants into the field, moving directly from
stop to stop. More challenging, however, is using
technology to mimic the type of free movement
through a landscape that a student might experience,
TEKIȴȍ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Pokémon Go uses augmented reality technology to layer animations of characters
and other features over real-life images of
streets, parks and other public spaces on
smart phones.
Credit: Matthew Corley/Shutterstock.com
for example, at field camp. In that setting, geologists-in-training are often turned loose for the day
to conduct independent field mapping, a task that
requires them to make their own decisions about
where to go and what outcrops to investigate. Jacqueline Houghton, a structural and field geologist
at the University of Leeds in England, wanted to
recreate that experience in the classroom, so she
looked to gaming technologies for inspiration.
Houghton and her colleagues created a virtual,
animated landscape of three field sites to render a
three-dimensional version of the world where students could “walk” around in the landscape, like in
a first-person video game. “The students get a blank
map that shows topography, and they walk around
and work out where they are,” noting rock types at
different locations.
It’s the little details the team included in the
simulation that catch students’ attention. The animated world includes hidden surprises, like a dead
sheep (common in the rural U.K. countryside) and
the occasional sounds of a Royal Air Force flyover.
Houghton says these touches entertain and intrigue
students, and provide the same sorts of “distractions” that students might encounter on traditional
field trips.
Houghton notes that the virtual trips replicate
the same struggles and challenges for students that
a traditional trip can provide — for example, missing
key observations, trying to finish quickly, or not
quite seeing the big picture. “What we see is [students] make the same mistakes” in the virtual field
trip as they do in a traditional trip. She adds that
the virtual reality (VR) trip helps her drive home
lessons about the geology of an area to students. “In
the real world, I can’t [always] send them back over
to an outcrop,” but in the VR world, students can
revisit an area again and again to collect details they
might have missed.
Often, students who can’t attend traditional field
trips, perhaps because of disabilities that affect their
mobility, are given alternative exercises like essays,
which deprives them of a field experience, Houghton
says. But on VR trips, she adds, everyone experiences
the same trip in the same way.
Beyond Pokémon:
&YKQIRXIHc7IEPMX]
In 2016, it was hard not to run into gaggles of
kids — and sometimes adults — wandering around
outside and huddling over their smart phones in
seemingly random locations. The reason for this
peculiar phenomenon was the sudden popularity
of Pokémon Go — a game that layers animations
of characters and other features from the cartoon
Pokémon over real-life images of streets, parks and
other public spaces on one’s smart phone.
The game is an example of a technology called
augmented reality, or AR. Like Pokémon Go, AR
applications often involve artificial animations that
appear atop images of real places on a screen.
Beyond entertainment, AR technology has been
taking off in advertising, retail and military applications, but it can also be used for education.
Art and natural history museums have integrated
the technology into exhibits, for example, to
encourage interaction and engagement of visitors
with displays.
AR has also made it into the classroom. Kent
Hups, a teacher at Northglenn High School in Northglenn, Colo., has been using AR in his classroom to
bring geologic maps to life. With an app called HP
Reveal, students use their phones to scan geologic
maps, and the app can then display pop-up images
of rock outcrops or three-dimensional hand samples
on top of the map.
Hups concentrated on a few locations in Colorado
with distinct geologic features and used a geologic
map of each spot. “I started to add depth to the maps,”
he says, explaining that in a 1:500,000 map showing
the entire state of Colorado, details and subtleties of
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Feature
In Kent Hups’ earth science course, students
at Northglenn High School in Colorado use
augmented reality to make geologic maps
come to life. An app on their smart phones
displays videos and photographs of geologic
sites around the state.
Credit: Kent Hups
geologic features can get lost. But by adding photos
of locations, students can see rocks, faults, unconformities and other geologic formations in three
dimensions, which brings them to life.
He’s been experimenting with broadening his
AR-enriched lessons to include cross sections and
hand samples as well. Using more detailed 7.5-minute (1:24,000) quadrangle maps, a standard scale of
topographic maps produced by the U.S. Geological
Survey (USGS), students “can scan [part of a map]
with their phone and the overlay will be a picture
of that very location.” Numbers associated with different scannable sites on the map also correspond to
bins in his classroom that contain hand samples of
the rocks at each site. “I can actually get the rocks in
their hands from that location,” Hups says. “They can
see it and touch it without leaving the classroom.”
Using AR in the classroom has increased accessibility for Hups’ ELL students, he says. For example,
Spanish-speaking students can scan part of the map
and have the lesson delivered to them in their native
language. “It’s a huge leap in teaching because a lot of
times we have kids that are disengaged if they don’t
understand,” he says. “But now I can take them on a
tour of this geology in a language they understand.”
and communication. Unlike the megapixel pictures
we take with our digital cameras or phones that
have millions of pixels, giga-imagery pictures are
composed of billions of pixels. This very high resolution can capture the incline of sand beds within a
100-meter-long outcrop — all within the same image
— allowing students to see both the fine details and
the big picture.
GIGAmacro, a company that has made a name for
itself by developing tools to produce such detailed
images, is putting a new spin on the integration of
technology into geology. Gene Cooper, the founder
of GIGAmacro, started his foray into giga-imagery
by taking 360-degree photographs in national parks.
He also worked with museums around the country
that expressed interest in having very high-resolution images of their collections and samples.
After some experimentation with equipment and
some creative computer programming, the company
created a way to photograph in incredible detail
and then allow users to view objects in a fast and
user-friendly way.
GIGAmacro’s equipment allows users to take
overlapping photos of objects — whether a hand
Giga-Imagery Zooms In
New technologies have helped make VR and AR
a possibility, but great imagery is a huge part of the
puzzle when it comes to recreating landscapes. Over
the last decade, the advent of extremely high-resolution imagery, often called giga-imagery, has
opened many new avenues for geology education
,MKEMQEKIV] SJ E FEWEPX XLMR WIGXMSR EX Ȧȉ XMQIW
magnification: On the GIGAmacro website, users can
compare two images of the same thin section using
both waveplate and brightfield lighting, just like you
would be able to do with a petrographic microscope.
Credit: GIGAmacro
TEKIȴȮ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
sample of rock or an insect, for example — in both
vertical and horizontal dimensions. Once stitched
together into a single image, the resulting giga-image
is seamless and zoomable, allowing the viewer to
see minute, sometimes microscopic, details without
any delayed loading. The technology has a definite
“wow” factor.
But the images can be used for much more
than just demonstration. Scientists, educators and
curators can scan a geologic sample or outcrop
and upload it to GIGAmacro’s website, or they can
use images already available on the site. They can
then have students annotate what they see right
on the image. With a free GiGAmacro account,
students can save their work, or even add to an
image as a class.
One example of an image available on GIGAmacro’s website is of a slab of fossiliferous sedimentary
rock from the Stonerose Interpretive Center and
Eocene Fossil Site in Republic, Wash. This particular
sample is chock full of fossils ranging from parts
of insects to leaves, each of which was identified
with virtual push pins by Stonerose scientists, who
included as much detail about the remains as possible, allowing students to study the rock and fossils
in minute detail.
There are also images of rock thin sections,
which allow students to view and interpret mineral grains, textures and fine-scale features. The
company is always working to improve the tools
available to users, Cooper says. “We would love to
connect more with geologists and other scientists
about what tools would make their jobs easier,” he
says. “How can we help them use this in a classroom setting?”
In the last several years, Callan Bentley, a geologist
at Northern Virginia Community College (and a
contributing editor of EARTH) and his students have
amassed more than 2,000 high-resolution giga-images, on scales ranging from whole outcrops to thin
sections. Bentley formed the Mid-Atlantic Geo-Image Collection (MAGIC) on GigaPan, showcasing
their work and creating a place to share resources
with other educators and students.
The images were made freely available to provide
access and opportunity, Bentley says. “Some of these
sites that we’ve made imagery of are in places that
are out of the way,” he says. “Students in Virginia
can access outcrops in South Africa and then be back
at their desks again in 45 seconds.” He adds that this
imagery can also provide access to people who might
not, for whatever reason, be able to reach mountaintops, valleys, outcrops or otherwise remote, or
inaccessible, field sites.
Another Tool in the Toolbox
Fieldwork is often thought of as integral to
geologic study, so being unable to participate in
fieldwork has long been a barrier to the discipline.
TEKIȴȁ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Imagery of this fossiliferous slab of
sedimentary rock from the Stonerose
Interpretive Center and Eocene Fossil
Site is available on GIGAmacro’s website. Fossils in the slab were identified
and annotated so interested users
can hover over each pin and learn
about each preserved organism.
Credit: GIGAmacro
Sometimes it is familial or work obligations that get
in the way of a student’s ability to participate, and
differently abled students have also traditionally
been precluded from most field experiences, says
Christopher Atchison, a faculty member in geoscience education at the University of Cincinnati and
executive director of the International Association
for Geoscience Diversity (IAGD).
About a decade ago, Atchison started exploring
how to tackle issues related to ableism and fieldwork. He created a class geared toward students
with physical disabilities — the plan was to use
VR for a culminating field trip to Mammoth Cave
National Park. But he decided that it would be good
to first get the students into Mammoth Cave during
the course, so he could later compare the field and
VR experiences to help develop how to structure
future classes.
The students in the new course were just like any
other group of future rock hounds, Atchison says.
During one class session, they focused on the basic
geology of cave and karst formation so the students
would be prepared for their visit to Mammoth Cave.
“They were sponges,” he says, very eager to learn and
experience a field trip in person.
Their visit to Mammoth Cave did not disappoint. “None of them were science majors, but they
were just glued to this whole experience because
they’d never been given this opportunity before.”
He says he realized that VR wasn’t the only answer
for addressing barriers to accessibility in geology.
The experience solidified Atchison’s
view that fieldwork should be open
to everyone. “The enjoyment and
excitement that I shared with these
students … completely changed my
focus and direction,” Atchison says. He
now advocates for accessible and inclusive
field trips, and has written about his efforts
in EARTH.
Most proponents of VR and AR in earth
science classrooms do not suggest that it should
replace field experiences altogether. Instead, they
see the technologies as educational tools that can be
leveraged in many different ways. “You can’t see the
subtlety of information” and teach observational skills
with the same level of depth using VR, Houghton
says. But using the tools can “prepare students for
fieldwork” in the real world and increase the diversity
of people being exposed to geology.
The technologies can also help manage large
student groups and, ultimately, create more inclusive learning communities. “One of my classes is EL
[English language]-specific, and right now I have
seven languages [represented] in that class,” Hollister
says. Those students have found ways to share their
ideas with the help of Google Translate and by sharing sketches, he says. This unique collaboration is
facilitated by VR technology, allowing them to communicate in the comfort of their classroom — a more
conducive setting for a diverse group of students
compared to the outdoors. “They were conversing
and making discoveries and learning things about
their new home — it’s really cool.”
Sharing information among peers, proposing
arm-waving hypotheses, and engaging in inevitable
arguments about whether a rock is granite or diorite
are experiences at the heart of learning geology,
and in the case of Hollister and other earth science
instructors, VR is helping grow communities of
students interested in doing just that.
Derouin is acting associate editor at EARTH.
TEKIȴȟ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Rafting the Main Salmon River across Idaho offers a thrilling
whitewater adventure, as well as a tour through several of
the state’s geologic provinces.
Credit: Bureau of Land Management
Travels in Geology
7&+8.3,8-*&12437.:*7
8-749,-8-*.)&-4'&8-41.8Lucas Joel
G
ive a river time and it will chart a path
through even the mightiest mountains,
cutting down through the rocky record
of Earth’s long history. Rafting down a
river, then, can give you a front-row seat to a geologic story that unfolds as you go past. Such is the
case on a trip down the Main Salmon River, which
courses first north and then west across northern
Idaho over Precambrian metamorphic rocks, as
well as granitic rocks of the Idaho Batholith, which
intruded into the crust during the Cretaceous Period
before being exposed at the surface. The finale of this
Salmon trip — which takes about six to eight days to
finish — arises as the river flows past what was once
the edge of North America and over former island
arcs sutured onto the continent during the Mesozoic.
I rafted the Main Salmon — also known as the
River of No Return — in August 2017 after driving to
Boise to meet up with my uncle, Bill Cross, a professional rafter, and his veteran crew of two: my aunt,
Polly Greist, a writing teacher, and Michael Parker,
a biologist. Bill is the kind of captain you want at
the oars when the rowing gets tough, as the effortlessness with which he threads boats through rapids
makes the ordeal look easy. It isn’t easy, of course, but
Bill literally wrote the book on whitewater rafting
in the western states: “Western Whitewater from
the Rockies to the Pacific: A River Guide for Raft,
Kayak, and Canoe.” He writes about rivers, and reads
whitewater as well as you’re reading these words.
I went on the trip partly to practice rafting and
fly-fishing. But I had another reason: I had to decide,
after our trip ended, if I should pack up my life and
move west, to California, or head back east to where
I had been living in Michigan. Nature, I hoped, might
help me make my decision.
The River of No Return
The Salmon River is the longest undammed
river in the lower 48 states, and the longest river
contained within a single state. The Salmon’s
TEKIȏȉ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
The Salmon River runs for about
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mountains of south central Idaho
and then westward, until it reaches
its confluence with the Snake River
along the Oregon border. The portion that most people raft flows
through the U.S. Forest Serviceadministered Frank Church River of
No Return Wilderness, from Corn
Creek to Vinegar Creek.
Credit: K. Cantner, AGI
Frank Church River of No
Return Wilderness. But
don’t worry: Though the
name “River of No Return”
sounds ominous, it refers
to when, in the early 20th
century, boaters used to
transport hunting parties
on one-way trips down
the Main Salmon. Today,
most rafters do not return
to their launch site at the end of their trip, so the
name still carries the same meaning.
Most river trips down the Main Salmon begin at
the boat ramp at Corn Creek Campground — about
75 kilometers west of North Fork, Idaho, by road —
where rafters rig their crafts and have their gear and
permit checked by a USFS ranger. There, we rigged
our two rafts in the hot summer sun, and I readied
myself for the unknown.
A Precambrian Send-off
8LIEYXLSVXLMVHJVSQPIJXTSWIW[MXLLMWJIPPS[VEJXIVWƴJVSQ
left, Bill Cross, Polly Greist and Michael Parker — before embarking
SRXLIMVXVMTHS[RXLI2EMREPQSR7MZIVMR&YKYWXȶȉȦȮ
Credit: Bill Cross
headwaters are in the mountains of south central
Idaho, and the river runs about 680 kilometers
until it reaches its confluence with the Snake
River along the Oregon border. The portion of the
Main Salmon that most people raft flows through
the U.S. Forest Service (USFS)-administered
At Corn Creek, I saw the opening of our geologic
tour: Precambrian metasedimentary rocks sticking
out alongside the riverbanks and atop forested hills.
This unit is part of the Belt Supergroup, a suite of
rocks that crop out not just here, but elsewhere
along the Salmon and in places like Glacier National
Park. The supergroup formed about 1.4 billion
years ago, though the exact timing of metamorphism is unclear, explains Reed Lewis, a research
geologist with the Idaho Geological Survey, who
was not on the trip. At least some of the deformation happened about 1.2 billion to 1 billion years
ago during the Grenville Orogeny, when mountains
rose along the eastern margin of proto-North
TEKIȏȦ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Cross prepares a raft before the group launches
from Corn Creek Campground. Metamorphosed sedimentary rocks of the Precambrian Belt Supergroup
underlie the landscape here, cropping out along the
river and on the slopes above.
Credit: Lucas Joel
America during assembly of the supercontinent
Rodinia. Further deformation likely happened
during the Cretaceous as the Idaho Batholith —
which is farther downstream — intruded.
Bill and I rowed in one of our two inflatable
rafts to some rapids upstream of the Corn Creek
Campground. He taught me how to ferry a boat
through the rapids to the opposite side of the river
— a tricky maneuver involving precise rowing,
a perfectly-angled boat and many frantic overthe-shoulder glances. I aimed our boat at a rocky
outcrop, where, after wrestling with rapids that
spun me this way and that, we landed. I scrambled
out and — indulging my inner rockhound — sampled some ancient, sparkling schists.
From Belt to Batholith to
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From Corn Creek the river briefly flows through
rocks of the Belt Supergroup, but by the time we
reached our first stop — Otter Beach Camp at
mile 10.1 — we were already rafting over the Idaho
Batholith. The first exposed rocks of the batholith
that rafters see are Cretaceous metamorphic rocks
that occur as foliated, black and white orthogneisses.
In later stretches, batholith rocks retain their original
crystalline character, appearing as salt-and-pepper granodiorites.
We assembled our cots on the white sands of
Otter Beach, while across the quiet river stood a
great, dead pine tree whose gnarled and naked limbs
stretched outward. Suspended in the higher branches
was a nest made of thick sticks, and perched near
the nest were two bald eagles. Another rafting trip
passed our camp, and we told the team to look up.
As the team slowly floated by, we all watched the
eagles as they peered back at us.
Around mile 18, the river slices through a kind of
geologic island amid the batholith: granitic Eocene
rocks of the Challis Magmatic Complex, which
intruded into the much older batholith that surrounds it. Floating onward from the Eocene granites,
we were enshrouded by smoke from some distant
wildfire as we came upon Black Creek Rapid, just
shy of mile 21.
There is nothing like having cold river water
splash over you on a hot day. However, those
splashes often come from wild rapids that can not
only soak your clothes, but also flip your boat if
you don’t navigate through them carefully. Rapids
can form when rivers narrow, or when flowing
water encounters sudden drop-offs in slope or
TEKIȏȶ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
&FSZIXLIEYXLSVPIJXERH5EVOIV
descend into the maelstrom of
Black Creek Rapid, one of the
toughest stretches on the Main
Salmon. Smoke from distant
wildfires left a haze over the river
during the trip.
Credit: Bill Cross
At Black Creek Rapid, near where rafters first encounter granitic
rocks of the Eocene Challis Complex, the calm that prevails immediately upstream suddenly turns to chaos as the river encounters
a boulder field. Here, Parker and Cross scope out a path through
the rapids from the shoreline.
Credit: Lucas Joel
obstacles like boulders plucked from the surrounding mountains. These things can create big waves
and swirling eddies in fast-moving waters littered
with exposed rocks — hence the need for experienced guides like Bill.
Black Creek Rapid, one of the toughest rapids on
the Main Salmon, formed several years ago thanks to
a debris flow that swept downstream from adjacent
Black Creek, just about where you first encounter
Challis Complex rocks. Above the rapids, the river is
a quiet pool, but in no time the dark still water turns
into white foam as the river drops down over boulders
deposited by the debris flow. Cross and Parker (who
can probably give you the scientific name of every
plant and animal on the river) docked the boats just
before the rapid, then climbed ashore to plot a course
through the turbulent waters. Back in the boats, we
floated downstream as the river narrowed into a dark
tongue that took us into the white chaos.
Hot Springs and a Change of
Course
The views of Challis rocks don’t last long before
the river takes you back into the batholith. At about
mile 22, we passed by natural hot springs called Barth
Hot Springs, which offer a warm respite from the
cold rapids and hard rowing. You can park your boat
on the left side of the river and make a short hike to
the springs.
“If you go farther north in Idaho, hot springs
decrease in number,” Lewis says. The source of
warmth beneath the springs isn’t definitively
TEKIȏȴ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Buckskin Bill’s Homestead
XQMPIȍȶSRXLIPIJXWMHISJXLI2EMREPQSR7MZIV
a group of unfamiliar structures emerge on the
riverbank — not geologic structures, but built. This is
the decades-old homestead of a mountain man named
Sylvan Hart, nicknamed “Buckskin Bill.” Hart settled
here during the Great Depression, and lived in Idaho’s
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ERHSXLIVXSSPWF]LERHFIJSVITEWWMRKE[E]MRȦȟȁȉ
The site is now a museum owned by a couple who run
a small store where you can buy snacks, water jugs,
knick-knacks and other souvenirs. If you have time,
stop here and go for a walk to recover from the hot
sun and get a sense for what it might have been like
to live on your own, deep in the wilderness.
A
Barth Hot Springs, a short hike from the river, offers a
respite from cold rapids and hard rowing.
LJ
Credit: Bill Cross
known, but Lewis says the heat may arise from
the same magmatic processes associated with crustal
extension in the Basin and Range province to the
south. The Basin and Range, perhaps the best
known example of which is found in Nevada’s many
linear, north-south-trending mountain ranges,
extends all the way from Mexico to southern Oregon and Idaho. As the crust in this vast region pulls
Cross surveys Bailey Rapid, where another raft flipped over in the
water, spilling unsecured gear into the river. Just beyond Bailey
Rapid, the river turns sharply to the southwest, following the trace
of Bargamin Creek Fault.
Credit: Lucas Joel
apart and thins, warm mantle rock rises closer to
the surface, providing a source of geothermal heat
across much of the West.
Several miles downstream from the hot springs
is Bailey Rapid, another monster: A boat just behind
ours took a wrong turn amid the whitewater and
their 4-meter raft, laden with gear, flipped amid the
whitewater. Their gear was not secure, and much of
it dumped into the river’s maw. We rescued a block
of cheese for them, but little else.
The next big geologic scene change comes at
about mile 32, soon after passing Bailey Rapid, with
rafters’ arrival at the Bargamin Creek Fault — a
northeast-trending normal fault that formed as the
Challis Complex intruded. The fault is no longer
active, but its effect on the river is clear from an
eagle’s view: Instead of continuing northwest, the
river turns sharply to the southwest and follows
the trace of the fault, running mostly through Belt
Supergroup rocks. “The fault is why the river takes
a turn there,” Lewis says. “It’s coming along and
it finds that nice soft rock made by the fault, and
it follows sub-parallel to that structure for quite
some distance.”
Then, as if the fault had never gotten in the
way, the river resumes its northwest trajectory
after the confluence with the South Fork of the
Salmon River. Here, the granite of the batholith is
yellowish, friable and unmetamorphosed, which
makes it easier to see the unaltered grains in this
rock with the naked eye compared to the batholith
rocks seen before reaching the fault.
TEKIȏȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
8LIIGPMTWISFWGYVIHEFSYXȟȁTIVGIRXSJXLIWYREX
Hungry Bar Camp along the Main Salmon, dimming
XLIQSVRMRKWYRPMKLXSRERSXLIV[MWIGPIEVcHE]
Credit: Bill Cross
An Eclipse and Sparkling Sands
Near mile 60 we laid over at Hungry Bar Camp.
That night, I fly-fished from one of our boats, but
the fish weren’t biting. Putting my rod aside, I spoke
to my aunt Polly about the crossroads I was at and
the choice I had to make about moving. We talked
about the need to face life’s challenges — that hard
8LIKVSYTXSSOMRXLIWSPEVIGPMTWISR&YKȶȦJVSQXLIGSQJSVX things can help one grow. Our conversation helped
of Hungry Bar Camp.
me make my decision; I did not catch a fish that night,
Credit: Bill Cross
but I did gain some wisdom.
The next morning, the sky was clear of clouds and
smoke, and the sun hung above the mountains upriver
from camp. It was Aug. 21, the day of the Great American Eclipse. Wearing our eclipse glasses, we looked
straight at the sun as the moon slowly blocked more
and more of its light. (We were just north of the path
of totality, in an area where about 98 percent of the sun
was obscured.) As the light grew dim and the air grew
cool, birds stopped chirping for many minutes as the
moon passed in front of the sun. I took off my glasses
at one point and made a small hole with my thumb
and forefinger, watching as the light poured through
the hole and projected crescent-shaped images on the
sand. A nearby tree had the same effect, projecting
dozens of tiny images of the eclipse from light streaming through spaces between leaves.
After the eclipse we resumed our trip on the
Erosion of the micaceous schists that surround T-Bone Creek river, floating past another strip of exposed Belt
Camp, like the rock seen here, contributes to the lithology of the Supergroup metamorphics at about mile 70. If you
beach sand, which sparkles in the sunlight.
stop over anywhere along this stretch of the river, I
suggest staying at T-Bone Creek Camp (mile 71.3).
Credit: Lucas Joel
TEKIȏȍ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Feature
Greist takes in the evening view along the river.
Credit: Bill Cross
T-Bone has a large beach that’s great for camping
and activities like Frisbee or badminton. Large outcrops of micaceous schist surround the camp, and
erosion of these rocks no doubt contributes to the
lithology of the beach: When the sun hits the beach
at the right angle, the abundant mica crystals glint
like diamonds in the sand.
The closing act of the trip, if you continue much
past Vinegar Creek Rapid at mile 78.4 to somewhere
like Spring Bar Campground in Riggins, takes you
out of the Idaho Batholith, past the ancient edge of
the North American continent. The now-familiar
igneous rocks of the batholith give way to different
terranes that accreted onto the continental margin,
likely during the late Paleozoic and early Mesozoic.
These terranes, which appear as multicolored drapes
on a geologic map of the state, display a parade of
rock types, from schists and marbles to amphibolites and deformed granodiorites. In the vicinity of
Riggins, the river becomes the Lower Salmon River,
which eventually meets up with the Snake River
toward the end of Hells Canyon — another river trip
filled with geologic delights.
We took our boats out at Carey Creek boat
ramp at mile 80.7, just downstream from Vinegar
Creek Rapid. From there we drove back to Boise,
and, after saying our goodbyes, I got in my car and
headed east.
Joel is a freelance science journalist. You can find
more of his work at www.lvjwriting.com.
Getting There & Getting Around
I
f you’re interested in a trip down the Main Salmon, you
have two options: put a trip together yourself, or hire a
professional outfitter to take you. Permits are required for
WIPJSVKERM^IHXVMTWFIX[IIR/YRIȶȉERHITXȮ5IVQMXW
are awarded through a lottery via www.recreation.gov,
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may be a good idea to have a lot of people from your
KVSYTETTP]5IVQMXWEVIRSXVIUYMVIHMJ]SYKS[MXLER
outfitter. For outfitter suggestions, check with the U.S.
Forest Service. Lastly, bring a waterproof guidebook that
you can keep open as you splash through waves. I highly
recommend “RiverMaps Guide to the Middle Fork and
Main Salmon Rivers, Idaho,” which contains the mileages
referenced above.
The closest major airport to the Corn Creek launch is
Boise Airport in Boise, Idaho. From there, you can drive
to the river, or take an air taxi to the town of Salmon —
EFSYX ȦȦȉ OMPSQIXIVW JVSQ XLI PEYRGL ƴ ERH EVVERKI
transport to the river from there. If you need a place to
stay near Corn Creek, I recommend heading to Salmon.
The town is small, but there are few options closer and
it has lodging, dining and stores where you can buy
Most river trips down the Main Salmon begin at the boat ramp at
Corn Creek Campground, where rafters rig their crafts and have
their gear and permit checked by a U.S. Forest Service ranger.
Credit: U.S. Department of Agriculture
last-minute rafting gear if needed. Wherever you stay,
the raft trip is one-way, so if you have a car, you will likely
want to find a way to shuttle it down river so it’s waiting
for you at the pull-out site. Shuttling services are available to transport vehicles. Most commercial group trips
end near Vinegar Creek, but if you are on a private trip,
]SYGERGSRXMRYIHS[RWXVIEQEFSYXȏȉOMPSQIXIVWXS
Riggins and on to the Snake River confluence.
TEKIȏȰ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
LJ
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Mineral Resource of the Month
CHROMIUM
Visit minerals.usgs.gov/minerals
for more information
PRODUCTION
Although chromium is a metal, it does not occur naturally in metallic form. Chromium can be found in many minerals, but the only
economically significant chromium-bearing mineral is chromite.
Chromite has been mined from four different deposit types: stratiform chromite, podiform chromite, placer chromite, and laterite
deposits. Most of the world’s resources, however, are located
in stratiform chromite deposits, such as the Bushveld Complex
in South Africa. The economic potential of chromite resources
depends on the thickness and continuity of the deposit and on the
grade of the ore. Many of the major stratiform chromite deposits
also contain economic levels of platinum, palladium, rhodium,
osmium, iridium and ruthenium.
Chromite seams (dark
PE]IVW PSGEXIH MR XLI
Bushveld Complex,
South Africa.
Credit: courtesy Klaus
Schultz, USGS
Metric tons
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U.S. chromite ore production,
which was minimal through the
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World Total
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United States
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TEKIȏȁ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Ȧȟȟȉ
ȶȉȉȉ
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Mineral Resource of the Month
CHROMIUM
CONSUMPTION
design by K. Cantner and N. Schmidgall, AGI
Metric tons
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apparent consumption are
related to stock market crashes.
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The major markets for chromium materials
are chromium chemicals, ferroalloys and
metal. The primary uses of chromium are
in stainless steels, nonferrous alloys and
chromium plating. Chromite ore can also be
roasted to make sodium dichromate, which
is subsequently converted to chromium
chemicals used in pigments and metal
coatings. Chromium is also an important
component in refractories, foundry applications, and as a nutrient.
• The word “chromium” is derived from the
Greek word “chroma,” which means color,
because many chromium compounds are
colorful. Without chromium, emeralds would
not be green and rubies would not be red.
• 8VMZEPIRXGLVSQMYQ(V...MWERMQTSVXERX
micronutrient and improves the efficiency of
insulin in individuals with impaired glucose
tolerance. Meats, vegetables, fruits and
grains are metabolic sources of chromium.
TEKIȏȟ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Stainless steel tube
flange used in water
piping.
Credit: public domain
Geomedia
Books: “Quakeland” Spotlights Seismic Risk
(EPPER'IRXPI]
I
was flying to Seattle when I finished
Kathryn Miles’ 2017 book, “Quakeland: On the Road to America’s Next
Devastating Earthquake.” I shut the
book with a shudder of dread. There’s
trouble brewing below the myriad coffee
shops, not just in Seattle, but also across
the Pacific Northwest. Seattle and the
surrounding region sit atop the Cascadia Subduction Zone (CSZ), where the
diminutive Juan de Fuca Plate dives eastward beneath the sizable North American
Plate, producing a chain of stratovolcanoes
arrayed along the coast like pearls on a
string — an explosive geohazard.
What worries me more, though, is
the multitude of faults that accommodate tectonic stress across the region.
These faults, headlined by the subduction zone megathrust fault, are capable
of slipping suddenly and releasing tremendous amounts of energy in the form
of earthquakes — potentially some of
the largest humans have ever seen. The
2011 magnitude-9 Tohoku earthquake
occurred across the ocean in a very similar
tectonic setting, and it was a seismological
monster, unleashing violent shaking and
a massive tsunami that inundated much
of Japan’s coastline.
Preserved in the estuaries of Puget
Sound, tsunami deposits from 1700 attest
to the last time the Cascadia megathrust
unleashed a major earthquake — estimated
to have been about magnitude 9. Historical accounts of an anomalous tsunami
in Japan unwittingly recorded evidence
of this quake, so it’s known that the CSZ
can send major tsunamis across the Pacific.
Yet the fault hasn’t moved significantly
in 300 years. And during that time, we’ve
built several major metropolises above
it — Seattle being the biggest.
I visited the city on a cold and rainy
day (not a rarity there). It occurred to me
that if I were unlucky enough to be in
Seattle when a magnitude-9 earthquake
struck, almost all the buildings would be
uninhabitable and the
city’s population would
head outside into the
cold rain — for days.
It’s a grim thought, but
just one of many that
occupied mental real
estate after I finished
reading “Quakeland.”
Miles isn’t a seismologist, or even a
geologist. Rather, she’s
a journalist who has
immersed herself in earthquakes with a
passionate zeal. Sometimes, it takes a nonspecialist to sort out what is most worth
reporting, and what will resonate most
with the public. And in that light, “Quakeland” offers a current, useful compilation
about earthquake hazards, science and
related policy, albeit one that’s presented
somewhat breathlessly and features a few
too many errors for my comfort.
Miles has a distinctive voice, and overall, the book — structured like a road trip
travelogue — has an informal feel. Miles
recounts historical earthquakes in the
United States and around the world: From
Tohoku to L’Aquila to Mexico City, some
of the examples she highlights remind us
that the violence and danger of earthquakes
are exacerbated by weak building codes and
loose substrates (like those that underlie
many parts of the Seattle area, for instance).
She dedicates chapters to earthquake
prediction, which, as she rightly notes,
is still beyond our abilities, as well as to
earthquake early-warning systems. In the
early-warning chapter, she includes a helpful review of best practices for preparing
for and surviving an earthquake.
In the chapter on the relationship
between hydraulic fracturing (“fracking”)
and earthquakes, the causal connection
between wastewater injection (which
often accompanies fracking operations)
and earthquake triggering should have
been made more explicit at the outset. She
“Quakeland: On the Road
to America’s Next Devastating Earthquake” by Kathryn Miles, Dutton/Penguin
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eventually raises the distinction, but it’s an important
issue that is often confused
in the public discourse about
fracking and deserves a clear
and prominent discussion.
Furthermore, Miles confuses the role of
sand in this process: Sand grains act not as
an “abrasive,” as she describes, but as tiny
support structures to prop open newly
fracked cracks in deeply buried rocks.
Nonetheless, this is a useful chapter, as it
explores the science of one of the more
prominent applications of seismology in
the minds of average citizens.
“Quakeland” would have benefitted
from a thorough review of the science
it describes before printing. There were
numerous errors, some small — hot spots
are described as “burning” and faults are
called “fault lines” — while others were significant, such as Yellowstone and Hawaii
being described as places where oceanic
crust is destroyed. In some cases, mistakes
were just sloppy: transposing south and
north in describing Coeur d’Alene’s position relative to the University of Idaho, for
instance, or failing to identify affiliations
or credentials of a source quoted as an
expert on geothermal energy. These things
should have been caught by Miles’ editor.
Thankfully, the word “temblor” never
appears in the book. For that, Kathryn
Miles gets my eternal gratitude!
Bentley is an assistant professor of geology at Northern Virginia Community College in Annandale, Va., and a contributing
editor at EARTH. He blogs about geology
at http://blogs.agu.org/mountainbeltway.
TEKIȍȉ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Conglomerate: A Geo Word Jumble
1. Acequia
2. Alford rotation
3. Axial-plane
cleavage
4. Brachylinear
5. Cryosol
6. Diaene
7. Discontinuity
8. Foreland
9. Gaseous transfer
10. Geophysiography
11. Goongarrite
12. Grumantite
13. Haldenhang
14. Hyalophane
15. Hydraulic action
16. Johannite
17. Keuper
0HJDÀRZPDUN
19. Mid-ocean rift
20. Mottles
21. Osmosis
22. Polyquartz
23. Pseudospondylium
24. Pseudosymmetry
25. Relative fugacity
26. Spinodal
decomposition
27. Stretch
28. Subseries
29. Thermal resistivity
30. Thomsenolite
31. Volcanic accident
This is a word search of terms from the Glossary of
Geology. Check out GeoWord of the Day at www.
americangeosciences.org/word. Words in the puzzle
may be hidden horizontally, vertically or diagonally,
and spelled in either forward or reverse order.
Puzzle solution appears in the Classifieds section.
Glossary of Geology
Fifth Edition, Revised
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Glossary of Geology, 5th Edition Revised.
Klaus K.E. Neuendorf
James P. Mehl Jr.
Julia A. Jackson
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GEOSCIENCES
INSTITUTE
SUBCRIBE at:
www.americangeosciences.org/word
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SEE DETAILS BELOW
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These mud volcanoes sit within an active pull-apart
basin bounded on both sides by major northwest-southeast trending strike-slip faults. The basin
contains, and shares a name with, a saline body of
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below the surface, and is named for the intersection
of two local roads.
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once existed here — including wave cut benches,
sandy shorelines and mussel shells deposited high
in the hills — was first described by geologist William
Blake, who was looking for a western railroad route.
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Grand Prismatic Hot
Spring in Wyoming’s
Yellowstone National
Park is the largest hot spring in the United States
and the third largest in the world. It owes its brilliant
bands of color to different species of thermophilic
bacteria and archaea that live in successively cooler
zones of water that encircle the center. Photo by
Gregg Beukelman.
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and clues in EARTH’s monthly digital editions. From those who
for the contest. Find out more about submitting your photos at
answer correctly, EARTH staff will randomly draw the names of
www.earthmagazine.org/whereonearth/submit, and send them to
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receive a free one-year subscription or renewal.
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Status of Recent
Geoscience Graduates 2017
By Carolyn Wilson
Photos from AGI's 2017 Life As a Geoscientist. Photographers clockwise from top left Victoria Heather; Mayra Martinez; Rob Thomas; Mary Lide Parker
Status of Recent
Geoscience Graduates
2017
The American Geosciences Institute’s (AGI) Status of Recent Geoscience
Graduates 2017 provides an overview of the demographics, activities and
experiences of geoscience degree recipients during the 2016-2017 academic
year. This research draws attention to student preparation in the geosciences,
their education and career path decisions, as well as provides other critical
insights into the newly minted geoscience workforce at the bachelor’s,
master’s and doctoral degree levels.
$15.00 (printed copy)
Carolyn Wilson
978-0922152643
Amazon purchase link: http://bit.ly/AmznRecentGraduates2017
Free digital download: http://bit.ly/AGIWorkforceReports
TEKIȍȴ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Down to Earth
With Geologist and Paleontologist David Wilcots
8LIE'SSHLSS
W
hen David Wilcots was
4 years old, his parents took him to the
American Museum of
Natural History in New York City where
he encountered his first giant dinosaur
skeleton: a roughly 27-meter-long sauropod named Apatosaurus (though at the
time it was still popularly known as Brontosaurus). “That just blew my mind,” he
remembers. His passion for paleontology
grew, branching from dinosaurs into early
mammals, and led him to major in geology
at Temple University in Philadelphia. In
1988, he earned a master’s in geology at
Fort Hays State University in Kansas.
But then, things didn’t go as planned.
“When I got out of grad school, I looked
for jobs in paleo, but couldn’t find any,”
he recalls. “Environmental geology was
the next best thing.” He began consulting
with business and government agencies,
and as time went on, his second choice
of career grew on him.
The Business of Geology
Today, Wilcots is the senior geologist and manager of environmental
projects at Sci-Tek Consultants, Inc., in
Philadelphia. His team includes civil and
geotechnical engineers, environmental
scientists, data analysts and software
programmers. They examine landscapes;
assess environments; and design, plan
and document environmental matters
for a broad client list that includes
municipalities, airports, lawyers, bankers, real estate developers and insurers.
The work sites are as diverse as the
clientele. Over the course of his career,
Wilcots has visited sites where companies do everything from retread airplane
tires to cover pretzels in chocolate. He
has been to highly contaminated federal
Superfund sites, and he has even dabbled
in the energy sector — spending one
brutally cold Pennsylvania winter helping
with the installation of a new
wind farm.
Environmental geologists,
he explains, spend a lot of time
in the field, which is part of the
appeal for him. Shortly after
our interview, he was bound
for a different kind of field: an
airfield. “I’ll be out on the runway, at the airport, supervising
a drill rig. So that’s a huge difference from being at a desk
behind a computer screen.”
Another part of the job that
he finds enjoyable bestows an
additional benefit. “You meet so
many different kinds of people,
young and old, and your communication skills just naturally
develop.” Interviewing munic- David Wilcots is a senior geologist and manager of
ipal officials, property owners environmental projects at Sci-Tek Consultants, Inc., in
and tenants is a requirement of Philadelphia. He is also a paleontologist and particithe job, but on any given day, pates in fossil hunting expeditions in the West.
he says, he might find himself Credit: Thea Boodhoo
interacting with anyone from
attorneys to insurers to operations man- Wyoming.” Wilcots gladly signed on
agers at manufacturing facilities.
with Alexander, and since then he has
Most days involve some time at a desk, joined paleontology expeditions in the
writing proposals or reports, and he has American West with groups from the
a hand in marketing and sales. “I’ve been Utah Geological Survey, the University of
an environmental geologist for about 23 Utah, and the Burke Museum of Natural
years, so business development is a signif- History and Culture in Seattle.
The participants of summer expediicant part of what I do,” he says. Unlike in
academia, where funding primarily comes tions include professional paleontologists
from grants, the business side of geology as well as volunteers like himself. The
depends on bringing in new clients, and volunteers, he says, come from “a whole
pitching projects to existing clients.
gamut of backgrounds: people who are
retired from teaching at the college
level or high school level, empty-nest
A Paleontologist on
moms, teenagers,” and even people who
XLIcMHI
spend the rest of the year as carpenAlthough his days are filled with envi- ters, lawyers, mechanical engineers or
ronmental geology projects, paleontology retail professionals.
is never far from his mind. “Back in 1993
This past summer, Wilcots spent
or so I got a call from John Alexander, four days at a dinosaur excavation site
[who was then] at the American Museum in northeastern Montana with paleonof Natural History; he was going to go tologist Gregory Wilson of the Burke
out West to look for Eocene [fossils] in Museum working on what is known as
TEKIȍȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Down to Earth
Wilcots stands in front of a drill rig on an
environmental geology project. He works
on a variety of projects assessing local
geology for environmental and engineering site evaluations.
Credit: courtesy of David Wilcots
the Tufts-Love Tyrannosaurus rex, which
according to the museum is the 15th
T. rex specimen that includes a skull. The
specimen is named for its discoverers,
Burke Museum volunteers Jason Love
and Luke Tufts.
After that, he drove south to his usual
sites in Wyoming, where, each summer,
he continues to hunt for Eocene mammal
fossils with Alexander — now also at the
Burke Museum.
The evolution of mammals has long
fascinated Wilcots, especially the phase
after the Mesozoic, when mammals
began filling the ecological niches left
by the extinction of the nonavian dinosaurs. “If you’re studying the Eocene,
you’re studying how mammals took it
to the next level.” It was during this era
when many of today’s major mammal
groups first appeared, he explains, along
with mammals that are no longer extant,
like the giant titanotheres — which were
related to horses and rhinos — and
hooved carnivores like Andrewsarchus
and Mesonyx.
Deep Time Meets
-MKLc8IGL
Despite describing himself as “not
technological,” Wilcots avidly follows
technological advances in both geology
and paleontology. When I asked him
what he thought the most exciting areas
are in each field, his answers weren’t
about new discoveries or theories — they
were about technology.
Wilcots noted the major impact that
geographic information systems, or GIS,
has had on the geosciences and his own
career is no exception. “When you’re writing a report or submitting that report to
a regulatory agency, and you’re showing
graphs from the [GIS] model that you put
the data in, that’s powerful,” he says. By
supporting your testimony with computer-generated models to express your data,
Wilcots says, the finished project “can be
very convincing to a client.”
When it comes to paleontology,
he is most excited about the advancements in three-dimensional scanning
and printing. “The ability to print things
in three dimensions and three-dimensionally map specimens or fossil sites
is really changing the game,” he says.
For example, he describes scanning a
2-meter dinosaur thighbone: “You can
three-dimensionally scan the bone and
then save it on a disk or a thumb drive
and print it out at another location.” This
process makes sharing fossil replicas
vastly easier, he says.
And there’s another interesting application for tiny fossils: Imagine taking a
very small specimen, “say the fossil chewing tooth of a mouse — it’s really tiny,
the size of a pinhead,” he says. “But with
three-dimensional scanning and printing,
you can blow that up 50 times larger so
you can really study it.” This could be
especially useful for researching Triassic
and Jurassic mammals, he says, most of
which were mouse-sized or smaller. “You
need all the help you can get.”
In his free time, Wilcots enjoys volunteering on paleontology expeditions in the
U.S. West.
Credit: courtesy of David Wilcots
TEKIȍȍ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Down to Earth
Wilcots also enjoys sharing his passion
for paleontology and geology with a wider
audience. In March, he gave a presentation,
“Center City Sedimentary Stratigraphy,”
on the geology underlying downtown Philadelphia as visible in two excavation sites
that exposed the Trenton Gravel Formation. He also speaks to school groups and
has created a website, Dinosaurs, Fossils
and Adventures, an online paleontology
resource for young people.
When it came to choosing a mascot
for the website, despite his professed
enthusiasm for carnivores, he went with
an East African plant-eating dinosaur,
Kentrosaurus. “I wanted to pick a dinosaur
that was cool-looking, but didn’t get much
play in the media,” he says. Kentrosaurus
“has plates and shoulder spikes. I thought,
‘That’s a really neat combination.’” Some
might say the same of Wilcots’ melding
of part-time paleontology and full-time
geology, both of which seem to suit
him perfectly.
Boodhoo (TheaBoodhoo.comMWEJVIIPERGI
science writer based in San Francisco.
“Greening” stormwater in Philadelphia
W
hen environmental geologist David Wilcots
NSMRIH GM8IO (SRWYPXERXW MR ȶȉȦȏ LI FIGEQI
involved with the Philadelphia Water Department’s Green
Stormwater Infrastructure project. Sci-Tek’s goal was to
redesign certain areas of the city’s urban landscape so
that “less stormwater goes into the sewage system” and
more goes into the ground, explains Wilcots. Doing so
not only helps prevent flooding, but also lightens the
load on sewage treatment plants. He manages a team
of designers, data analysts and environmental scientists
who are “gathering the stormwater flow data from around
the city at hundreds of locations.”
The project often focuses on small strips of green —
tree trenches, detention basins, bioswales or bump-outs,
to name a few — in the midst of the concrete jungle. Tree
trenches, for example, “are curbed strips of grass that
hold trees,” he describes. “They may be along the side of
a building or might separate the north and southbound
lanes of a busy street, or they may be in large parking
lots to provide areas where water can infiltrate. They’re
sort of like elliptical islands of grass.” Bump-outs are
similar but protrude from sidewalks.
I was fascinated by this project because we’ve all
seen, parked next to or even walked over these common
features of city roadways, but we rarely, if ever, hear their
names or think about what’s below them. And they’re
useful for much more than shade and aesthetic value:
“All these features are covered with grass, but below the
grass is soil that is conducive to infiltration,” Wilcots says.
Soils with a lot of sand are best at allowing water to filter
down, “then below the sand will be a network of large
rocks and, possibly, slotted piping that further promotes
downward infiltration of
stormwater.” The project
is still ongoing, and cities
across the United States
are now implementing
methods that Wilcots
and others refined in the
streets of Philadelphia.
“This is going on around
the country,” Wilcots says.
“Philadelphia is on the
leading edge of it.”
8'
A stormwater bioswale, like
this one in Philadelphia, helps
slow the flooding of paved
areas by diverting water downward, away from the sewer
system.
Credit: courtesy of David Wilcots
TEKIȍȰ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Benchmarks
/YRIȦȍȦȟȟȦ Mount Pinatubo Erupts
Lucas Joel
T
wenty-seven years ago this
month, the calm in central
Luzon, the largest and most
populous island in the Philippines, turned to chaos. On June 15,
1991, Mount Pinatubo disgorged 5 cubic
kilometers of material over a few hours,
and ash clouds soared 35 kilometers into
the atmosphere. The substantial eruption — the second largest of the 20th
century — burned itself into memories
and history books.
Before the eruption, 1 million people
lived around the volcano, including members of the island’s native Aeta tribe, who
called the volcano’s slopes their home.
The safety of those living in the area
— who needed to know whether, and
when, to evacuate — ultimately rested
with volcanologists monitoring the volcano. Mount Pinatubo showed signs of
unrest months before the eruption, but
it was uncertain right up until the very
end when it might blow, or even if an
eruption would happen at all.
Pinatubo Stirs
There is no sophisticated monitoring equipment to thank for sensing
that something was brewing beneath
Pinatubo. Instead, early suspicions came
from Catholic nuns living near
the volcano.
On July 16, 1990, a magnitude-7.8 earthquake struck
about 100 kilometers northeast of Pinatubo. The nuns
then saw steam issuing from
the ground and felt small
earthquakes near the volcano.
In August, the nuns and some
members of the Aeta tribe
traveled to Manila, where
they communicated what
they had observed to the late
volcanologist Ray Punongbayan, who was then director
of the Philippine Institute of
Volcanology and Seismology
(PHIVOLCS). Punongbayan
relayed the nuns’ tale to Chris
Newhall, a volcanologist then
with the U.S. Geological Survey (USGS), during a phone Mount Pinatubo seen from Clark Air Base on Luzon
call, but Newhall couldn’t be SR/YRIȦȶȦȟȟȦ
sure that these signs were a Credit: U.S. Geological Survey
buildup to an eruption.
“The typical recurrence period volcanoes dotting the edge of the Pacific
between eruptions at Pinatubo was on Plate from North America around to
the order of a thousand years,” Newhall East Asia and Oceania. Although it grew
says, with the last eruption having hap- quiet again after its July 1990 outburst,
pened about 500 years earlier. Forecasting more explosions came on April 2, 1991.
when the next eruption would occur These were phreatic explosions — mostly
was a complete steam, with no magma; the steam blasted
mystery. “There through surface rock, creating a line
was nothing you of craters on the northeast side of the
could hang your volcano. Next to the craters, the blasts
hat on,” he says. stripped trees of their branches, and ash
Mount Pina- dusted tree leaves for a dozen kilometers
tubo sits on the or more in every direction.
Pacific Ocean’s
The craters continued to jet steam,
Ring of Fire and again the nuns and the Aeta trav— a string of eled to alert Punongbayan. PHIVOLCS
Scientists from the U.S. Geological Survey and the Philippine
Institute of Volcanology and Seismology unload volcano monitoring gear from a U.S. Air Force helicopter on the east side
of Mount Pinatubo.
Credit: U.S. Geological Survey
TEKIȍȮ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Benchmarks
&FYMPHMRKGIRXIVSJMQEKIGSPPETWIHYRHIVXLI[IMKLXSJEWLXLEX
fell on Clark Air Base from Pinatubo’s eruption.
Credit: Richard Hoblitt, USGS
installed seismometers on Pinatubo, and
the agency began listening to the planet’s stirrings. “They [detected] lots of
earthquakes — lots of small earthquakes,”
Newhall says. “Immediately that tipped
off Punongbayan that something was
amiss at Pinatubo.”
Pinatubo Awakens
On April 7, 1991, Punongbayan called
Newhall at USGS headquarters in Reston,
Va., to tell him about the activity. “My
ears perked up,” Newhall says. He asked
if PHIVOLCS wanted help from USGS to
monitor the volcano. Punongbayan said
yes, after which Newhall asked the Mission
Director of the United States Agency for
International Development (USAID) in
Manila to grant USGS permission to fly a
team to the Philippines.
USGS scientists in the Volcano
Disaster Assistance Program (VDAP),
created in 1986, stand ready to respond
to volcanic disasters wherever they may
occur around the world. Newhall was
part of the VDAP team when Pinatubo
was showing signs
of unrest, but VDAP
deployment is decided
upon by USAID,
which declined two
requests for assistance
from Punongbayan.
The USAID director, Newhall explains,
did not think there was enough evidence of
an impending eruption to justify deploying VDAP. However, clearly something
potentially hazardous was happening, so
Newhall went around the director. He
called a contact at NOAA, who put him
in touch with an official at Clark Air Base
on Luzon, which at the time was one of
the largest U.S. military bases in the world.
Newhall asked the official if the military
was aware of the activity at Pinatubo. The
official confirmed they were, he says. “And
they asked me: ‘When can you be here?’”
Newhall explained to the military the
impasse with USAID. The Air Force
then called the U.S. Ambassador to
the Philippines, who made a call to the
USAID director. “I got a telegram from
USAID that said: ‘You are to take the
next available flight [to the Philippines],
and you have $20,000, and do not feel
compelled to spend it all.’” Newhall says
he didn’t like having to go behind the
director’s back to gain authorization.
“But, in my judgment, we had to do
that,” he says.
After Newhall
and his VDAP colleagues landed, they
deployed instruments
to measure the seismicity, gas emissions
and ground swelling
around the volcano,
but it was still not
clear whether or not
the volcano would
erupt. Seismicity escalated, though, and
on June 5, the team issued a warning that
an eruption would likely happen within
two weeks.
On June 7, the first magma came out
of the ground, but the flow was only a
trickle and it was not explosive. Then, on
June 12, Philippines Independence Day,
Pinatubo began releasing its payload. “It
looked like an atomic bomb going off,”
Newhall says. “That ended all doubt about
whether it was going to erupt.”
Pinatubo Erupts
John Ewert, another volcanologist
with USGS, flew to the Philippines on
May 23 to support VDAP and the Pinatubo Volcano Observatory (PVO) — a
crude monitoring station set up by USGS
and PHIVOLCS in empty bedrooms at
Clark Air Base. Ewert’s plane flew over
Katmai National Park and Preserve,
which in 1912 hosted the largest volcanic
eruption of the 20th century at Novarupta. He saw from the plane the massive
ash flows that came from that eruption.
When he got to the Philippines, he saw
the ash beds that formed during Pinatubo’s previous eruptions, which blanket
the countryside around the volcano, and
he recalls thinking they looked “pretty
similar” to the Katmai deposits.
The Air Force helicoptered PVO scientists to and from Pinatubo, bypassing
the rough roads through jungle-covered terrain. “As we got into June …
and we got a better sense of how far
hazardous flows had traveled from the
volcano from past eruptions, we began
to be concerned for our own safety.” The
eruptions included pyroclastic flows,
“incandescently hot avalanches of rock
and ash that move very quickly and
incinerate and destroy everything in
Seismographs at the Pinatubo Volcano Observatory were used to
monitor the volcano in the days and weeks leading up to the eruption.
Credit: U.S. Geological Survey
TEKIȍȁ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Benchmarks
their path,” Ewert says. Clark Air Base
sat atop an area flattened by ancient
pyroclastic flows. While flatlands make
for good landing strips, Ewert says, he
knew that flows from a new eruption
could easily reach them.
It was clear and beautiful outside on
the morning of June 12, when, just before
9 a.m., the “atomic bomb” went off. Ash
soared more than 20 kilometers into
the sky, and eventually spread into an
umbrella shape.
“Everybody wants to know: Is that
the big one? Is that the big one?” Ewert
says. It was not the big one. After a few
hours of quiet, the seismometers detected
more shaking at the volcano. There was
an explosion that night, another the next
morning, and another in the afternoon on
June 14. Seismic activity increased, and on
the night of June 14, using military-issue
infrared viewing equipment, the team saw
incandescent, pyroclastic flows ejecting
from the volcano.
Nature writes stories that
make Hollywood blush.
– John Ewert,
U.S. Geological Survey
“The smaller eruptions that occurred
a few days before the cataclysmic eruption were the biggest and fastest things
I’d ever seen,” recalls Andy Lockhart, a
geophysicist with USGS who was part of
the VDAP team. “I thought I might die;
I thought all my friends there might die;
and all the people we were supposed to
protect might die.”
By June 14, most of the 14,000 personnel at Clark Air Base had been
evacuated, with only the PVO team and
core military staff left behind. As dawn
broke on June 15, Ewert saw ash filling
the entire horizon. But the ash wasn’t the
only thing lurking in the atmosphere —
Typhoon Yunya hit the Philippines at
the same time. The typhoon’s cyclonic
winds swept the ash near and far, smothering PVO. “It’s dark, and it’s raining
stones and ash, and the wind and the
rain — it was impressive,” Ewert says.
“We heard roaring sounds,” which came
Lahars from the Mount Pinatubo eruption roared down river valleys, destroying homes
and bridges and displacing thousands of people.
Credit: U.S. Geological Survey
from lahars — slurries of volcanic and
other debris mixed with water — flowing down rivers near Clark Air Base.
“Nature writes stories that make Hollywood blush,” he says.
Ewert and his team finally evacuated. The main eruption — the one that
Pinatubo is famous for — came on the
afternoon of June 15. Dubbed a Plinian eruption, Pinatubo released so much
material that it collapsed upon itself and
formed a caldera.
Between 20,000 and 25,000 people
lived close enough to the volcano that if
they had remained home, they would’ve
been killed in all likelihood, Ewert says.
Most residents heeded evacuation warnings, however, and the estimated death
toll was far less — about 300 to 400.
Most casualties happened as a result of
the ash and the typhoon: wet ash piled
on roofs, leading to roof collapses as the
ground shook during the tumult of the
caldera collapse.
Fallout
After the June 15 eruption, Pinatubo resumed its slumber. Studies of
the eruption and its buildup led to new
insights about eruptions in general.
Ewert points to the earthquakes that
predated the eruption and happened
far away from the volcano — including
the earthquake that hit in July 1990.
Magma movement beneath Pinatubo
had pressurized the crust around the
volcano, and nearby faults failed and
slipped. Similar earthquakes have since
been spotted around other erupting
volcanoes, like Soufrière Hills Volcano
on the Caribbean island of Montserrat,
and today, volcanologists look for such
earthquakes when assessing a volcano’s
eruption potential.
Ewert, Newhall and Lockhart note the
success of the international collaboration
that went into forecasting Pinatubo’s
eruption. Pinatubo was the first deployment of VDAP, and working alongside
PHIVOLCS — as well as the U.S. military,
the Aeta and the nuns — the team managed to help save thousands of lives. “The
leaders of the team were frankly heroic
— Ray Punongbayan, Chris Newhall, Rick
Hoblitt and Dave Harlow. These guys
were working under terrible pressure to
get it right,” Lockhart says.
The event underscores the difficulty
of trying to do scientific work in an
environment where there is limited
time. “Scientists are routinely taught
to be very cautious about what they
say,” Newhall says. “In a crisis situation,
you don’t have that luxury.” Instead,
you need to give others your best guess
about what could happen, because there
is no room for hesitation. Newhall says
he walked away from the experience
with a stark realization: “Things that
you think are worst-case scenarios can
actually happen.”
Joel is a freelance science journalist.
You can find more of his work at www.
lvjwriting.com.
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The AGI Foundation’s (AGIF) programs impact young people, educators, researchers, the public, and policymakers
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Geologic Column
Rebranding Alexander
;EVH(LIW[SVXL
“ With great power comes great responsibility.” — Various (including “Amazing
Fantasy #15,” the comic in which Spider0DQZDVƛLUVWLQWURGXFHG
A
s near as I can make out, William Bonney was a psychopath.
Before Pat Garrett shot him
dead in 1881, Bonney was
known to have killed at least eight men (he
claimed 21), all before he reached age 22.
He’s known to history as Billy the Kid, and
that label “Kid” softens our view of him
somewhat. Kids are the delightful young of
the tribe — playful and sometimes mischievous, but psychopaths? “Never,” you say,
thinking of a well-loved kid of your own,
perhaps. That’s why Billy’s been portrayed
in movies and on TV as basically loveable
but a bit mixed up.
He brings to mind another young overachiever, Alexander III of Macedon. This
superhero of history, universally known
as Alexander the Great, was intent upon
getting into real estate in a big way by
conquering a bigger chunk of the planet
than anybody before him. He’s called
“Great” for that reason, but that sobriquet
has been handed out too readily at times,
especially to royals. You would think that
it would be reserved for the true heroes
of humanity: for the inventive plumber
perhaps, who brought us hot baths and
flush toilets, or for the genius who first
put the bubbles into beer. Anyway, after
two and a half thousand years, I think
Alexander needs rebranding. We could
take a leaf from young Billy Bonney’s
book and try “Sandy the Kid,” but up on
Olympus — where he’s made his home
since his followers made him a god — he
likely wouldn’t be pleased and might send
a few thunderbolts our way.
Let’s review Alexander’s biography.
As a boy, he had the best education
possible, with none other than Aristotle as his tutor. The small kingdom of
Macedonia that Alexander, at age 20,
inherited from his dad, King Philip,
was expanded a hundred-fold by the
time he died at 32. Everywhere his military exploits took him, he stamped his
mark on the landscape by building cities,
which he called Alexandria, until they
dotted the landscape like so many Trump
Towers. He could no doubt claim that,
at his inauguration as King of Kings,
the crowd was bigger than it had been
for Darius and Xerxes, earlier holders
of the office, so Alexander the Great is
certainly a credible title.
Give a ruler a bad name
and a whole culture is
tarred and feathered.
whether a human coated with naphtha
could be set alight. Alexander chose a
young slave, covered him with tar, and
set him aflame.
I’m sure that, nowadays, Alexander
would have argued that the slave died a
willing martyr to his Emperor’s commitment to furthering the science of human
combustion. Spider-Man might have
branded him Alexander the Irresponsible, though I would prefer Alexander
the Appalling. But give a ruler a bad
name and a whole culture is tarred
and feathered. Think Vlad the Impaler
and Transylvania.
Let’s reject all that history — it’s fake
news anyway — and concentrate on his
years of innocence. Hearsay and gossip
both authenticate the following story
of Alexander as a kid: When he was 12,
Alexander went with King Philip to buy
a horse. The strongest one at the sale was
a massive animal called Bucephalus, but
the horse was so wild no one could ride
him. “Let me try, Dad,” said Alexander,
and before the King could say “Nay!” the
prince was popping the equine equivalent of a wheelie right ‘round the show
ring. “He’s a genius,” the accompanying
sycophants acclaimed, so Philip bought
Bucephalus for his son, and from that
day boy and horse used to hang together,
inseparable companions, down at the
Royal Stables.
So, I suggest that an
appropriate new name for
the Great Conqueror is
Alexander the Stable Genius.
Why, it’s as up-to-date as
today’s headlines.
That is, until we consider the dark
side. In his march of conquest, he killed
thousands of people, razed myriad cities
and trampled cultures into dust. Disturbing stories of moral turpitude persist,
and historians point to booze as the
fundamental problem. Alexander spent
most of his downtime listening to the
flattery of sycophants while guzzling
wine by the amphora. (It’s a pity the
Scots were a little tardy in exporting
golf or that might have taken his mind
off the bottle.) Indeed, he reportedly
died in a drunken orgy in Babylon,
rather than from fever as official history
records, and in another
story he is said to have
committed murder to
win an argument. The
homicide was in what is
today Iraq, arguably the
site of the richest reservoir of crude oil in the
world, and even in the
4th century BC known
for seepages of a tarry
hydrocarbon called
naphtha. The drink-fueled dispute arose over Credit: Antonio Martinez Cortizas
TEKIȰȏ•/YRIȶȉȦȁ• EARTH • www.earthmagazine.org
Chesworth
is
professor
emeritus at the University of Guelph, Canada, and
Fellow of the Geological
Society of America. Email:
wcheswor@uoguelph.ca. The
views expressed are his own.
DIRECTORY OF
GEOSCIENCE DEPARTMENTS
53rd Edition 2018
Directory of
Geoscience
Departments
and other geoscience organizations
UPDATED FOR 2018
53rd Edition 2018
The Directory of Geoscience Departments is
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departments, museums, federal agencies,
geological surveys, and research institutions.
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The American Geosciences Institute
4220 King Street, Alexandria, VA 22302
Phone: 703/379-2480; Fax: 703/379-7563
Email: pubs@americangeosciences.org
image: ©Bruce Molnia, Terra Photographics from AGI’s ESW Image Bank
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