U T A H G E O L O G I C A L S U R V E Y
Volume 43, Number 1 January 2011
UTAH'S GEOLOGIC HAZARDS
Perspective Although the increased rate of retire- decade to maintain existing staffing
ments represents a loss of valuable exper- levels. There is national concern about
tise, it also represents opportunities for what has been called the “Great Crew
new geology graduates to join the UGS. Change”: an aging workforce juxtaposed
Today’s graduates leave college with dif- against an anemic supply of qualified and
ferent skill sets than what their predeces- trained scientists and engineers (Status
sors had—for example, almost all have of the Geoscience Workforce, American
good computer skills and are GIS literate. Geological Institute Report, 2009).
In addition, today’s geologic challenges Although a “Great Crew Change” seems
require a broader geoscience skill set to have started at the UGS, we see little
by Richard G. Allis compared to traditional geology needs evidence that the supply of graduates (or
several decades ago. Despite the increased experienced candidates) is affecting the
Over the past 12 months the UGS has had rate of retirements and resignations, we quality of applicants. Indeed, the number
a staff turnover rate of close to 10 percent. have been able to fill all the openings with of students enrolled in Earth science post-
Collectively, the outgoing staff represent talented people whom we hope will stay graduate programs at Utah’s universities
a loss of over 200 years of experience. and have productive careers with the UGS. is reportedly strong. It remains to be seen
About half of these were retirements, and The dominant degree for geoscientists at whether this situation will change once
half were resignations. This turnover rate the UGS is a master’s degree (55 percent; the economy rebounds and the private
is more than double what has been typical 30 percent have a bachelor’s degree and sector starts more aggressive hiring.
for the UGS over the past 10 years. The 13 percent have a
high turnover is due to a variety of factors, doctorate). This
but one obvious factor has influenced the pattern is similar to
retirements—that is the evolving age other state geologi-
profile of staff geoscientists. Seven years cal surveys across
ago the age profile for geoscientists at the the U.S., as is the
UGS had a single peak between 45 and age profile with a
55 years old, and two-thirds of the staff peak between 50
were over the age of 45. Presently, that and 60 years old.
age peak has moved seven years, and When these two
a greater number of geoscientists are factors are consid-
considering retirement. The peak has ered together, state
shrunk in relative size, but the age profile geological surveys
suggests the increased rate of retirements will need about
will continue for another decade. A sec- 500 new master’s-
ondary, younger, age peak is now showing level graduates
up as replacements fill the vacancies. over the next
State of Utah Editorial Staff Vicky Clarke Geologic Mapping Grant Willis
Gary R. Herbert, Governor Lori Douglas, Stevie Emerson, Jon King, Douglas Sprinkel,
Jeremy Gleason, Jay Hill Janice Hayden, J. Buck Ehler,
Department of Natural Resources
Land Subsidence and Earth State Energy Program Kent Brown, Basia Matyjasik,
Michael Styler, Executive Director
Fissures in Cedar Valley.........................1 Chris Tallackson Don Clark, Bob Biek, Paul Kuehne
Updated Landslide Maps of Utah ................4 UGS Board Denise Beaudoin, Jerriann Ernsten, Ground Water and Paleontology
Kenneth Puchlik, Chair
GPS Monitoring of Slow-Moving William Loughlin Jack Hamilton
Brandon Malman, Jim Levy, Michael Lowe
Will Chatwin, Deborah Boren, James Kirkland, Janae Wallace,
Landslides .............................................6 Tom Tripp Alisa Schofield
Alair Emory, Alex Dalpé-Charron, Martha Hayden, Hugh Hurlow,
Liquefaction in the April 15, 2010, Mark Bunnell Donald Harris
Sherry Childers, Stefan Wilson, Don DeBlieux, Kim Nay,
M 4.5 Randolph Earthquake..................7 Kevin Carter (Trust Lands
Alex Scott Paul Inkenbrandt, Lucy Jordan,
Glad You Asked ..........................................8 Geologic Hazards Steve Bowman Kevin Thomas, Rebecca Medina,
Richard Giraud, William Lund, Walid Sabbah, Rich Emerson,
Teacher’s Corner ........................................9 UGS Staff Greg McDonald, Jessica Castleton, Stefan Kirby, Scott Madsen,
GeoSights .................................................10 Administration Gregg Beukelman, Chris DuRoss, Toby Hooker
Survey News ............................................11 Richard G. Allis, Director Tyler Knudsen, Corey Unger,
Energy and Minerals David Tabet
Energy News ............................................12 Kimm Harty, Deputy Director Lisa Brown, Jim Ollerton,
Robert Blackett, Craig Morgan,
Barry Solomon, Adam McKean
New Publications .....................................13 John Kingsley, Associate Director
Mike Laine, Jeff Quick, Taylor Boden,
Starr Losee, Secretary/Receptionist Geologic Information and Outreach Thomas Chidsey, Cheryl Gustin,
Dianne Davis, Administrative Secretary Sandra Eldredge Tom Dempster, Brigitte Hucka,
Design: Jeremy Gleason Kathi Galusha, Accounting Officer Christine Wilkerson, Patricia Stokes, Stephanie Carney, Ammon McDonald,
Linda Bennett, Accounting Technician Mark Milligan, Stephanie Earls,
Cover: An active landslide on the Wasatch Plateau in Ken Krahulec, Valerie Davis,
Michael Hylland, Technical Reviewer Emily Chapman, Lance Weaver,
the Seely Creek drainage. The lower landslide averaged Brad Wolverton, Sonja Heuscher,
Robert Ressetar, Technical Reviewer Gentry Hammerschmid, Jim Davis,
14 feet of movement per year between 2004 and 2009. Mike Vanden Berg, Andrew Rupke,
Photograph by Rich Giraud. Marshall Robinson Mark Gwynn
Survey Notes is published three times yearly by Utah Geological Survey, 1594 W. North Temple, Suite 3110, Salt Lake City, Utah 84116; (801) 537-3300. The Utah Geological Survey provides timely
scientific information about Utah’s geologic environment, resources, and hazards. The UGS is a division of the Department of Natural Resources. Single copies of Survey Notes are distributed free of
charge within the United States and reproduction is encouraged with recognition of source. Copies are available at geology.utah.gov/surveynotes. ISSN 1061-7930
LAND SUBSIDENCE AND EARTH
FISSURES IN CEDAR VALLEY,
by William Lund, Tyler Knudsen, Paul Inkenbrandt, and Mike Lowe
In May 2009, Enoch City contacted the Utah Geological Survey (UGS) to
investigate a possible “fault” that was damaging streets, sidewalks, and
curbs and gutters in a new subdivision in north Enoch. During a recon-
naissance investigation, the UGS found a 2.4-mile-long earth fissure that
had formed in response to land subsidence caused by ground-water over-
draft of the local aquifer. In the affected subdivision, the fissure crosses Vertical displacement along
the Enoch-graben-west fis-
several undeveloped lots, and in addition to damaging streets and side-
sure has damaged 3-year-old
walks, vertical displacement across the fissure has reversed the flow direc-
tion of a sewer line so that it is no longer possible to gravity-drain sewage
in the Parkview subdivision;
effluent from the subdivision. The likely relation of the fissure to ground-
view is to the south.
water pumping was communicated to Enoch City, the Utah Division of
Water Rights, Iron County, and the Central Iron
County Water Conservancy District (CICWCD).
The CICWCD subsequently funded the UGS to
conduct a detailed investigation of the Enoch
earth fissure, and to determine if land subsidence
and earth fissures were affecting other areas in
Although earth fissures have been documented
in the rural Escalante Desert, the discovery of the
Enoch fissure is significant because it is the first
one in Utah that has encroached into a develop-
ing area. In other western states, land subsid-
ence and earth fissures have caused hundreds of
millions of dollars in damage to buildings, roads,
bridges, railroads, utilities, well casings, dams,
canals, and other infrastructure.
Our investigation focused on an evaluation of
water-table decline and the distribution, thick-
ness, and texture of basin-fill deposits in Cedar
Valley—these are all critical components to land
subsidence and fissure formation in the arid
southwestern United States. A comparison of
historical water-level data with new UGS mea-
surements shows that ground-water discharge
in excess of recharge since 1939 has lowered the
ground-water surface in Cedar Valley by as much
as 114 feet. Using nearly 300 well drillers’ logs,
we produced a map and simplified cross sections
of Cedar Valley’s basin-fill sediments that show a
high percentage of fine-grained material (chiefly
clay) that is particularly prone to compaction
Location of earth fissures in Cedar Valley. White lines
are contours of approximately equal ground-surface
elevation change (feet) since 1950, based on comparison
of historical leveling and modern GPS data.
JANUARY 2011 1
High-precision Global Positioning System (GPS) surveying of tionally, linear features of unknown origin observed on aerial photos
benchmark elevations indicates that more than 110 square miles of and the presence of an isolated sinkhole south of State Route 56 are
the ground surface in Cedar Valley has subsided as much as 4 feet generally along trend with the earth fissures west of Quichapa Lake,
since 1950. In response to the land subsidence, at least 3.9 miles and may indicate the possibility of a more extensive zone of fissuring
(total length) of earth fissures have formed in the western and north- on the west side of Cedar Valley.
eastern parts of Cedar Valley. The Enoch-graben-west earth fissure Our investigation results show that the maximum amount of land
is the longest (2.4 miles) fissure, and is the only fissure that exhibits subsidence and earth fissure formation in Cedar Valley coincide with
vertical displacement. Significant fissure-related damage in Cedar areas of significant ground-water-level decline and the presence of
Valley is currently limited to the partially developed Parkview subdi- compressible fine-grained sediment in the subsurface. We conclude
vision in Enoch City; however, to the north the Enoch-graben-west that long-term ground-water pumping in excess of recharge is the
fissure also trends through and has displaced the ground surface cause of the land subsidence and earth fissures in Cedar Valley. If
in a heavily used livestock pasture/feeding area creating a poten- ground-water levels in Cedar Valley continue to decline 3 feet per year
tial for ground-water contamination. Aerial photographs show that (current average rate of decline), average basin-wide subsidence will
the Enoch-graben-west fissure began forming more than 50 years likely continue at a rate of 0.04 to 2.4 inches per year. Continued
ago, and that the fissure grew approximately 900 feet to the south
between 1997 and 2006. The main developed area of Enoch City
lies approximately 1000 feet south of the current fissure tip. Addi- Schematic cross section showing water
wells and the distribution of fine-grained
sediments across southern Cedar Valley;
see map of change in ground-water
depth for location of cross section.
ABOUT THE AUTHORS 2 Tyler Knudsen is a
Project Geologist with the
3 Paul Inkenbrandt graduated
from the University of Southern
4 Mike Lowe has been with
the UGS since 1989 and has
UGS Geologic Hazards Indiana with a B.S. degree in been involved with geologic-
1 William Lund has 38 years of experience as an engineering Program. He has a B.S. Geology in 2005. He went on to mapping projects, geologic-hazard
geologist—7 years with geotechnical consulting firms in degree in Geology from work for the Kentucky Geologi- assessments, and ground-water
Arizona, California, and Oregon, and 31 years with the UGS. the University of Utah and cal Survey for a year, and then investigations. He is currently
He is a former deputy director of the UGS, presently is the an M.S. degree in Geol- moved to Utah to attain an M.S. manager of the Ground-Water and
Geologic Hazards Program Senior Scientist, and is manager ogy from the University of degree in Geology from Utah Paleontology Program. Prior to
of the UGS’ Southern Regional Office in Cedar City. He Nevada, Las Vegas. Since State University. He completed joining the UGS, he worked as a
is a Licensed Professional Geologist in Utah, Registered joining the UGS in 2006, his thesis on Cache Valley aqui- well-site geologist in the petroleum
Geologist in Arizona, and Certified Engineering Geologist Tyler's work has focused on fers in fall 2010. He has been industry in Texas from 1981 to
in Oregon, and is a past president of the Intermountain geologic-hazard mapping with the UGS Ground-Water 1982, and was County Geologist
Section of the Association of Engineering Geologists, Utah and paleoseismic studies and Paleontology Program since for Davis and Weber Counties from
Geological Association, and Dixie Geological Society. in southwestern Utah. September 2009. 1985 to 1989.
2 SURVEY NOTES
ground-water overdraft and resultant subsidence will likely cause Based on the results of our study, the CICWCD has provided addi-
existing fissures to lengthen and new fissures to form that may even- tional funding for the UGS to prepare suggested policy recommen-
tually impact developed neighborhoods in Cedar Valley. Additionally, dations for managing the Cedar Valley aquifer to prevent future
earth fissures could provide a direct path for contaminated surface subsidence and fissure formation, and for preventing additional
water to reach the Cedar Valley aquifer, which is a major source of infrastructure damage in existing subsidence areas where fissures
culinary water. either have formed or may form in the future.
( Well estimated as pumping > 200 acre-ft/year
Change in ground-water depth EXPLANATION pumping > 200 acre-ft/year
( Well estimated as !
in Cedar Valley from September ( Fissure floor shallow bedrock
! Well estimatedandpumping > 200 acre-ft/year
1939 to October 2009. Fissure section
Ground-water Level Change
ft (negative indicates ground-water rise)
Valley floorand shallow bedrock
Bedrock - 114 Change
Ground-water and shallow bedrock
Ground-waterindicates ground-water rise)
ft (negative Level Change
91 - 100
ft (negative indicates ground-water rise)
101 - 114
81 - 90
101 -- 114
1 91 -71 - 80
81 -61 - 70
71 -51 - 60
61 - 70
51 - 60
41 - 50
51 - 60
41 - 50
41 -31 - 40
31 -21 - 30
21 -11 - 20
1 - 10
1 -2 - 0
-2 - -2 - 0
0 1 2 3 4
00 1 1 2 2 3 Miles
! Enoch !
( ( !
( ( !
Study Area !
( ( !
Study Area !
( ! !
( ( !
! ! !
( ( ( !
Study Area !
( ! !
( ( !
(( § (
!! ¦ !
! ! §
( ( ¨
4 Fort City
( Hills Hamilton
R12W R11W R10W
R12W R11W !
( JANUARY 2011 3
MAPS OF UTA
by Ashley H. Elliott and Kimm
more than 5 percent of Utah. The maps
published a statewide show various types of landslides includ-
map and database compila- ing generally deep-seated, slow-moving
tion of landslides using pre-1989 landslides (such as rotational and trans-
Significant economic losses are associ- published and unpublished sources. lational slides); fast-moving, generally
ated with landslides, and Utah contains Since then, many new geologic maps and shallow landslides (debris flows and
numerous landslides and landslide-prone updated studies have been published slides); earthquake-induced landslides
geologic units. In the early 1980s and that show additional landslide locations. (lateral spreads and flows); and land-
mid-2000s, above-normal precipitation In an effort to incorporate this new infor- slides undifferentiated from other Qua-
resulted in many landslides that caused mation and improve the understand- ternary deposits (such as talus, colluvial,
millions of dollars in losses. Many land- ing of landslides and their distribution and rock-fall deposits). In addition, the
slides in Utah result from the reactiva- throughout Utah, we created an updated GIS data provide more-specific landslide
tion of pre-existing landslides, hillslope version of the landslide maps and data- attribute information including depth of
modifications of landslide-prone geo- base using a geographic information landslide deposit, type of material, type
logic units, and natural gravity-related system (GIS). The updated information of movement, historical landslide events,
downslope earth movements. Exposure is available in GIS format as well as PDF landslide-prone geologic units, possible
to landslide hazards only increases as format and depicts 46 topographic land- movement causes, and original map ref-
development expands onto hillslopes, slide maps at a scale of 1:100,000 (1 inch erences.
onto alluvial fans at the mouths of flood- = 1.6 miles). The new maps add land-
prone canyons, and into other landslide- Local jurisdictions, developers, geotech-
slide data documented in 240 geologic nical consultants, the general public,
prone areas. maps and internal UGS landslide inves- and others interested in landslides can
To increase awareness of the land- tigations completed between 1989 and use the landslide maps and database to
slide hazard in Utah, the Utah Geologi- mid-2007. These new data allowed us identify potential landslide hazards and
cal Survey (UGS) in 1991 to refine some of the the need for site-specific geologic-hazard
existing landslide and geotechnical investigations in areas
boundaries and add of proposed development. Although
approximately 12,000 proper planning and avoidance of land-
to the approximately slide-prone areas are usually the best
10,000 previously ways to reduce landslide-related losses,
documented. avoidance is not always possible. Where
The maps and asso-
asso avoidance is not possible, site-specific
ciated GIS data geologic-hazard and geotechnical inves-
provide a way to tigations can identify engineering tech-
identify the loca
loca- niques that may be used to stabilize
tion and extent of slopes or reduce the impacts from land-
ing. The more The updated Landslide Maps of Utah
than 22,000 land
land- (2010, by A.H. Elliot and K.M. Harty)
slides depicted on are available on DVD as Utah Geological
the maps cover Survey Map 246DM.
Examples of damage caused by landsliding in the mid-2000s. A guest house
destroyed by a 2005 rock fall in Provo (above) and damage to a house in South
Weber caused by a rapidly moving landslide in 2006 (left).
4 SURVEY NOTES
Landslide maps for the northwestern
portion of the Kanab 30' x 60'
quadrangle as depicted in the earlier
UGS compilation (below) and the
updated compilation (right). The
updated map shows added landslides
and redefined landslide boundaries
based on new information.
For additional information on
landslides in Utah, refer to the
following UGS publications:
Case, W.F., 2001, Landslides – what they are,
why they occur: Utah Geological Survey Public
Information Series 74, available online at
Christenson, G.E., and Ashland, F.X., 2007, A
plan to reduce losses from geologic hazards
in Utah – recommendations of the Governor’s
Geologic Hazards Working Group 2006-2007:
Utah Geological Survey Circular 104, 30 p.
Deep or unclassified landslide – Generally 10 feet (3 m) thick or more and shows characteristic
Giraud, R.E., and Shaw, L.M., 2007, Landslide
landslide morphology. May include areas where landslide density is too great to show individual susceptibility map of Utah: Utah Geologi-
landslides separately. cal Survey Map 228DM, 11 p., 1 plate, scale
Landslide undifferentiated from talus and/or colluvial deposits – May include deep or shallow
landslides mapped with talus and/or colluvial deposits.
Utah Geological Survey, 1998, Homeowner’s
Landslide and/or landslide undifferentiated from talus, colluvial, rock-fall, glacial, and soil- guide to recognizing and reducing landslide
creep deposits – May include deep or shallow landslides mapped with talus, colluvial, rock-fall,
glacial, and/or soil-creep deposits; primarily mapped and compiled by Roger B. Colton, U.S. Geo- damage on their property: Utah Geological
logical Survey. Survey Public Information Series 58, available
online at geology.utah.gov/online_html/pi/
Not classified – Includes areas not mapped in the original studies compiled for this map, as well as
mapped areas with no identified landsliding. pi-58/index.htm.
JANUARY 2011 5
The Geologic Hazards Program has an ongo- by Richard Giraud and
ing long-term Global Positioning System (GPS) Greg McDonald
monitoring program to determine movement
activity in several northern Utah landslides.
Landslides may move so slowly that their move-
ment is imperceptible to humans. A geolo-
gist investigating a slow-moving landslide may
determine it to be dormant and stable, based In contrast, slow-moving landslides generally
on the landslide’s appearance and short-term An example of a clearly active
display the following: landslide on the Wasatch Pla-
movement monitoring. However, the landslide
could be moving slowly, and the consequences • possible extensive vegetation cover, teau in the Seely Creek drain-
age (above). The landslide
of assuming the landslide is stable and safe to • smooth, undulating surface,
shows a lack of vegetation,
build on could be disastrous. Therefore, while • lack of ground cracks, and hummocky rough surface, and
these landslides appear stable, precise long-
• faint landslide head, toe, and internal distinctive head and toe fea-
term measurements are needed to evaluate if
features. tures. The lower landslide av-
they are moving. Slow-moving landslides that
eraged 14 feet of movement per
we have targeted for monitoring can move as Ground cracks and other sharp features may year between 2004 and 2009.
slowly as half an inch per year or less. develop on slow-moving landslides; however, Photograph taken September
Determining if a landslide is actually moving erosion generally mutes and obscures these 24, 2009. (See front cover.)
using geologic observations of the landslide sur- features as they develop. On a slow-moving
face can be difficult in the case of slow-moving landslide, the features can erode faster than
landslides. Landslides that move several feet they develop, giving the landslide a dormant and
per year are generally easy to recognize as active
because the landslide surface is rough, appears
disturbed, and displays other freshly developed
landslide features. Landslides with recent sig-
nificant movement commonly display the fol-
• lack of vegetation or disturbed vegetation
(for example, tilted trees),
• hummocky, rough surface,
• fresh ground cracks, and
• sharp, distinctive landslide head, toe, and GPS base station and transmitting antenna used for
internal features. monitoring slow-moving landslides (left). The base sta-
tion site is on bedrock and is assumed to be stationary
with respect to nearby monitored landslides.
6 SURVEY NOTES
The Bear Wallow landslide complex near Snowbasin
(left) is an example of a slow-moving landslide, show-
ing vegetation cover and a smooth undulating landslide
surface. Parts of some internal landslides within the
complex have moved as rapidly as 8 inches per year,
but most monitored points move 1 inch or less per year.
Photograph taken December 3, 2009.
THE APRIL 15, 2010,
M 4.5 RANDOLPH
stable appearance when the landslide
is actually unstable and moving slowly.
Multiple measurements also provide
movement rates and direction for dis-
One method of determining slow rates tinct survey points on a landslide. A by Chris DuRoss
of landslide movement is with a survey- history of landslide movement aids
grade GPS instrument that uses infor- in anticipating future landslide move-
mation broadcast by a satellite network ment, managing landslide movement The UGS conducted a brief field reconnaissance
to accurately determine the location of problems, and providing information following the April 15, 2010, magnitude (M) 4.5
points on the landslide within approxi- to aid subsequent landslide investiga- Randolph earthquake, which occurred about
mately 0.5 inch horizontal and 2 inches tion. 6 miles northeast of Randolph near the base
vertical. GPS monitoring involves The Geologic Hazards Program cur- of the Crawford Mountains in northern Utah.
remeasuring the points on the land- rently monitors several slow-moving The Randolph earthquake was unusual in that
slide surface over time. Depend- or potentially slow-moving landslides it generated liquefaction (rare for M <5), includ-
ing on annual precipitation, several in northern Utah. Site selection for ing sand boils (eruptions of liquefied sand)
years of monitoring may be needed monitoring is based on nearby urban along the Bear River about a half mile west of
to identify movement. Our monitor- development, risk, and available moni- the earthquake epicenter. The earthquake is
ing program includes collecting GPS toring resources. The following land- thus one of the smallest recorded with modern
measurements once a year unless sig- slides are currently monitored: instrumentation to generate liquefaction. We
nificant movement is detected; in that attribute the occurrence of liquefaction to highly
• Green Pond and Bear susceptible sediments very near the epicenter;
case, measurement frequency may be Wallow, Snowbasin Road,
increased to collect additional data however, anomalously high ground motions
State Route 226, Weber may have also contributed to the liquefaction.
while the landslide is moving. Land- and Morgan Counties.
slides rarely move uniformly along
their entire length, so repeated moni- • Creekside Drive, Mountain
Sand boils (eruptions of liquefied sand) formed along the
toring of points distributed through- Green, Morgan County.
Bear River during the April 15, 2010, Randolph earth-
out the entire landslide is necessary to • Springhill Drive, North quake. Scale card is about 6.5 inches long.
identify movement and plot its distri- Salt Lake, Davis County
bution. Additional monitoring points (example of a slow-moving
are needed outside the landslide to landslide in a subdivision).
determine landslide boundaries.
• Potato Hill and Little Valley,
Our main goal is to detect repeated Draper, Salt Lake County.
landslide movement over a period of
several years in landslides that appear • Unnamed landslide near
to be dormant or slow moving. If Mill Hollow Reservoir,
movement is detected, our monitoring Wasatch County.
program can be refined to determine • Coal Hill, east of Zion
if the landslide moves continuously National Park, State
throughout the year or seasonally (gen- Route 9, Kane County.
erally during the spring). Movement
Monitoring results for the Spring-
patterns can then be compared with
hill Drive landslide are available at
records of precipitation and ground-
water levels to see what associations
may exist. Other studies have shown
Additional information on landslides
that periods of above-normal precipita-
in Utah is available at geology.utah.
tion and high ground-water levels com-
monly trigger landslide movement.
JANUARY 2011 7
Glad You Asked
What are the Roots of Geobotany?
by Jim Davis Desert trumpet (Eriogonum inflatum), above, on the Colorado Plateau, June 1949. Desert trumpet is
an indicator plant for sulfur-rich soils and gypsiferous ore deposits. Photo by Helen Cannon, courtesy of
the U.S. Geological Survey.
Plants can enlighten geologists as to
the rock beneath. Geobotany, also called Prince's plume (Stanleya pinnata), below, tolerates highly mineralized soil and indicates selenium and
phytogeography, is the scientific study of sulfur-rich soils, and gypsum deposits. Photo courtesy of Wayne Padgett, Bureau of Land Management.
the distribution of plants. Climate is con-
sidered the primary control on plant life, each claim several endemic species. In
but within a particular climatic region the the Uinta Basin, Graham’s beardtongue
rock beneath soil—known as the parent is found only on sparsely vegetated expo-
material of soil—is typically the key sures of the upper Green River Formation
factor influencing the vegetation growing oil shale deposits. Graham’s beardtongue
above. Rock ultimately determines soil could come under increasing threat in
moisture characteristics, nutrient avail- the future due to loss of habitat from oil
ability, and concentrations of essential and gas exploration, drilling, and tar sand
elements. Therefore, certain plants and oil shale mining, and consequently
are associated with specific rock types. has been proposed for a threatened status
Limestone, dolomite, shale, gypsum, listing under the Endangered Species
chert, gabbro, rock salt, and ultramafic Act.
rocks (e.g., dunite, peridotite, serpenti-
nite), for example, are known for their The use of plants to find ore bodies is
distinctive floras. Since before the advent called geobotanical prospecting. It has been
of agriculture humans have used plants effective in locating mineral deposits
as a guide to find sought-after rocks and worldwide, such as tin and tungsten plants as a tool for prospecting carnotite,
minerals. Today, the methodologies of in England; nickel, cobalt, and iron in a radioactive uranium ore. Cannon con-
geobotany are still applicable, practical, Russia; copper and silver in Montana; firmed that Astragalus species (including
and even cost-effective to the geologist. bitumen in California and by the Caspian milk-vetch and locoweed) pinpoint areas
Sea; and copper and nickel in central of selenium-rich uranium ore. Cannon
Dramatic changes in vegetation can occur and southern Africa. There are three also documented 50 other plants on
with changes in geology. In mountain commonly applied methods in geobotan- the plateau associated with mineralized
ranges of the Great Basin, big sagebrush ical prospecting: (1) mapping of indicator ground.
growing on sandstone abruptly transi- plants, (2) assessing plant appearance
tions to bristlecone pine on dolomite. and physiology, and (3) chemical testing For half a century, aerial photo interpreta-
The distribution of the California poppy of plants known to accumulate specific tion has been used as a tool for locating
in Arizona closely correlates with copper elements. indicator plants, anomalous vegetation
mineralization, which in turn corre- patterns, and evaluating plant health.
sponds with fault lines. In Utah, many Indicator Plant Mapping Indicator plant mapping has gained a
of the state’s endemic plant species powerful tool in the past few decades
Indicator plant species mark sites that are
(those found nowhere else on Earth) are with remote sensing, or the imaging of
likely enriched in a particular element or
restricted to growing on a single geologic Earth via satellite. Remote sensing uses
mineral. Usually these places are toxic or
unit—the Green River, Moenkopi, parts of the electromagnetic spectrum,
intolerable for other plant species, elimi-
Navajo, Mancos, and Chinle Formations such as infrared or ultraviolet light, to
nating any competition. Here in Utah,
detect plant species otherwise undetect-
prince’s plume grows in selenium- and
able when just the visible-light spectrum
calcium-rich soil; tufted evening-prim-
is examined. These plants are then used
rose, onion, wild buckwheat in calcium-
to glean clues about an area’s geology.
and sulfur-rich soil; and desert trumpet
Because so much of Earth’s bedrock is
grows in gypsiferous soil.
covered by vegetation, interpreting the
In southeastern Utah on the Colorado flora from imagery derived from remote
Plateau, geologist Helen Cannon in the sensing has been an increasingly impor-
1940s and 1950s pioneered the use of tant technique in geologic mapping.
Graham's beardtongue (Penstemon grahamii) is endemic to Utah's Uinta Basin and the adjacent Piceance Basin of
Colorado. It grows only on the upper Green River Formation. Photo courtesy of Michael Vanden Berg.
8 SURVEY NOTES