U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007-3046

September 2007

The Desert Laboratory Repeat Photography Collection—An 

Invaluable Archive Documenting Landscape Change

The U.S. Geological Survey 

(USGS) is the guardian of the largest 

archive of “repeat photographs” in the 

world—the Desert Laboratory Collection—which contains images not 

only from the American Southwest, 

but also from northwestern Mexico 

and Kenya. Repeat photographs are 

used to document landscape changes 

over time and are taken at precisely 

the same locations at specific sites at 

different times. 

History of Repeat Photography and 

the Desert Laboratory Collection

The Desert Laboratory Repeat 

Photography Collection is rooted 

in the work of a Bavarian professor, Sebastian Finsterwalder, who 

pioneered the technique of repeat 

photography. Beginning in 1889, 

Finsterwalder compared older and 

newer photographs he had taken of 

mountain glaciers to estimate rates of 

glacial retreat (melting) in the Alps. 

Before the 1950s, only a few studies 

used repeat photography as a scientific tool in the United States. In 1956-

1957, Homer Shantz repeated images 

he had taken on 1919-20 and 1924 

excursions from Cape Town to Cairo 

in Africa (Shantz and Turner, 1958). 

This publication, the first book-length 

report of landscape change relying 

entirely on repeat photography, was 

highly influential in the fledgling field. 

In the late 1950s, Jim MacDonald from the University of Arizona in 

Tucson wanted to analyze vegetation 

change documented in repeat photographs as a proxy for climatological data. McDonald recruited James 

Rodney Hastings to conduct field work 

on repeat photography of the Sonoran 

Desert. Hastings’s project gained the 

attention of Raymond M. Turner, and 

in the summer of 1960, they began a 

long collaboration to systematically 

replicate historical photographs of 

the region. This effort culminated in 

the classic book The Changing Mile

(Hastings and Turner, 1965), which 

documents long-term vegetation 

change in the vertical mile of elevation 

that encompasses the Sonoran Desert. 

This book was recently updated as The 

The Desert Laboratory Repeat 

Photography Collection, the 

largest collection of its kind in the 

world, is housed at the U.S. Geological Survey (USGS) in Tucson, 

Arizona. The collection preserves 

thousands of photos taken precisely in the same places but at 

different times. This archive of 

“repeat photographs” documents 

changes in the desert landscape 

and vegetation of the American 

Southwest, and also includes 

images from northwestern Mexico 

and Kenya. These images

are an invaluable asset to help

understand the effects of climate

variation and land-use practices on 

arid and semiarid environments.

Desert Laboratory 

Collection 

CICESE Collection

500 km

310 mi

Map of the western United States and Mexico 

showing the locations of camera stations used 

by the Desert Laboratory Repeat Photography 

Collection and Centro de Investigación 

Científica y de Educación Superior de Ensenada 

(CICESE) in collaboration with USGS scientists. 

The five regions with the most photographic 

matches are northern Arizona (1,904 stations), 

southern Arizona (1,904 stations), southern 

Utah (902 stations), Baja California (636 

stations), and southern Nevada (467 stations).

These repeat photographs document vegetation change on a hillside in Baja California. The 

left view taken in 1966 shows cirio (center) and cardón (left and right midground), as well 

as other woody plant species typical of this desert region. The right image taken in 1996 

documents the relative growth rates and life spans of cirio and cardón. The cirio at center 

has doubled in size, and the individual directly behind it in 1966 is now dead. Both cardón 

remain alive and have grown more slowly than the cirio in the intervening 30 years.
Changing Mile Revisited (Turner and 

others, 2003). 

The Desert Laboratory Collection, established by Turner in 1960, 

greatly expanded as the applications 

for repeat photography increased. In 

the early 1980s, Robert Webb engaged 

Turner, by then a member of the USGS, 

to study ecosystem recovery at abandoned ghost towns in the Mojave Desert. In 1989, Turner retired from the 

USGS, and Webb became the guardian of the collection. Webb applied 

the repeat-photography technique 

to a wide variety of research questions ranging from long-term channel 

change of regional rivers—such as 

change along the Colorado River in 

Grand Canyon—to documentation 

of changes in permanent vegetation 

plots in the Mojave Desert. Turner, 

meanwhile, continued to use repeat 

photography in documenting the 

combined effects of climate variability 

and land-use practices, including an 

expansion of Shantz’s work in Kenya 

(Turner and others, 1995). The collection now includes matches of photographs that date to the 1860s.

In the early 1960s, Hastings and 

Turner used repeat photography to 

help in studying the biogeography of 

desert plants in Baja California, Mexico. In the mid-1990s, Stephen Bullock 

of Centro de Investigación Científica 

y de Educación Superior de Ensenada 

(CICESE), a Mexican government 

agency in Ensenada, Baja California, 

asked Turner and Webb to help assess 

landscape change on the Baja Peninsula, focusing on long-term change 

in columnar succulent plant species 

affected by land-use practices. This 

ongoing work has shown systematic 

changes in the populations of highly 

valued plant species on the peninsula 

(Bullock and others, 2005).

As of 2007, the Desert Laboratory Collection contains about 35,000 

negatives and transparencies taken 

at 4,961 camera stations. A total of 

6,766 original photographs taken 

at these camera stations were used 

to create 9,658 matches (many images 

have been matched multiple times). 

The largest number of matches was 

made in Grand Canyon, the site of 

ongoing studies related to the effects 

of Glen Canyon Dam on the Colorado 

River (Webb, 1996). The southern 

and northern Arizona regions have 

the most matches (1,904), followed 

by southern Utah (902). A total of 636 

camera stations have been established 

in Baja California and another 150 in 

Kenya.

Repeat Photography in Action—

Some Examples

Understanding Long-term Change in the 

Central Desert of Baja California

The 10-year collaboration in Baja 

California between USGS and CICESE 

focuses on quantifying rates and 

directions of change in plant populations and communities over the last 

century in the Vizcaíno Region of the 

Sonoran Desert. This effort documents long-term trends in mortality 

and “recruitment” of different plant 

species, and the growth rates and ages 

of two species— the columnar succulents cirio (Fouquieria columnaris) and 

cardón (Pachycereus pringlei)—that 

are emblematic of this region. Factors that may affect changes in plant 

communities and individual plants 

include plant harvesting, livestock 

grazing, off-road vehicle use, soil 

properties, climatic fluctuations, and 

geomorphic (land-shaping) processes, 

such as floods and stream-channel 

change. The project’s long-term goal 

is to create and maintain a baseline 

photographic archive for the region by 

compiling historical data from many 

widely dispersed sources and adding 

data from new sites to fill some critical 

gaps in the coverage of amount and 

rate of landscape change.

Tracking the Encroachment of Woody 

Vegetation in the Desert Grassland of 

Southern Arizona

Historically, the desert grassland 

of southeastern Arizona and southwestern New Mexico was relatively 

free of woody vegetation (Turner and 

others, 2003). Two factors associated 

with European settlement changed 

this ecosystem—(1) fires set by lightning strikes or by Native Americans 

were actively suppressed, and (2) 

livestock consumed the fine fuels that 

formerly carried fires across the landscape. In addition, a climatic variation 

that favored increased winter rainfall during much of the past century 

encouraged woody species, notably 

native mesquite (Prosopis velutina and 

P. glandulosa) to expand their distribution from wash habitats to uplands. 

Repeat photos in the Desert Laboratory Collection continue to document 

these changes and the resulting disappearance of the once-open grassland 

and the establishment of a thornscrub 

Repeat photographs looking to the northwest from the summit of Huérfano Butte on the Santa Rita Experimental Range south 

of Tucson, Arizona, showing vegetation and landscape changes. The left view to the northwest taken in 1902 shows a desert 

grassland with desert hackberry as the dominant woody plant, and velvet mesquite are few and widely scattered. The right photo 

taken in 1986 shows that the formerly open grassland is now a thorn-scrub savanna following the large increase of mesquite, 

whereas the abundance of hackberry remains essentially unchanged, and most of the plants present in 1902 have persisted. Also 

note the new road in the 1986 image, showing the human influence on this landscape.
savannah dominated by woody 

leguminous trees, particularly 

mesquite.

Documenting Changes in Riparian 

Vegetation in the Southwestern 

United States

Plant communities along 

river margins (“riparian” vegetation) in the southwestern United 

States are threatened by water 

development, particularly the 

excessive use of ground water. 

Repeat photographs in the Desert 

Laboratory Collection show that 

large changes in riparian vegetation have occurred throughout the 

region (Webb and others, 2007), 

ranging from total removal in 

areas where ground-water extraction is excessive to large increases 

in areas once either barren or 

too swampy to admit growth of 

woody species. Increases have 

occurred both in native and nonnative riparian vegetation. Nonnative tamarisk (Tamarix ramosissima) forms monospecific stands 

that appear to exclude native species along several river reaches, 

but the establishment of native 

stands dominated by cottonwood 

(Populus fremontii) has occurred 

along numerous smaller rivers in 

the region, notably the San Pedro 

River in southeastern Arizona 

(Webb and others, 2007). 

Change in riparian vegetation 

is inextricably linked to both climatic and geomorphic processes. 

Opportunities for the establishment of woody riparian vegetation followed down-cutting of 

arroyos in the late 19th and early 

20th centuries that drained waterlogged floodplains. Periods of high 

winter rainfall during the early 

and late 20th century led to large 

winter floods, which simultaneously eliminated riparian vegetation and promoted germination 

and establishment of native and 

non-native species. Establishment 

of woody vegetation within arroyo 

walls promotes sedimentation on 

low floodplains, which promotes 

additional vegetation growth. 

Estimating Debris-flow Frequency

Debris flows are a type of flash 

flood that occur periodically in the 

tributaries of the Colorado River in 

Grand Canyon and elsewhere in the 

region. They transport large boulders into the Colorado River and its 

tributaries, creating constrictions 

and rapids. The resulting interaction 

between debris flows and the river 

strongly influences the geomorphology. Because few tributaries are 

measured for flow and the region is 

so remote, knowledge of when debris 

flows occurred in the past and their 

effect on the river was not well known. 

Using repeat photography, Griffiths 

and others (2004) determined that on 

average five debris flows occur every 

year, based on occurrence at 160 

tributaries in Grand Canyon (about 

20% of the total number). They used 

the repeat-photography information 

as the basis of a statistical model of 

debris-flow frequency in Grand Canyon by comparing the tributaries that 

produced debris flows versus those 

that did not over a 100-year period.

These photographs of 

the Escalante River at 

Escalante, Utah, document 

the interaction of riparian 

vegetation and channel 

morphology, which 

could lead to sediment 

accumulation and the 

filling of arroyos. The top 

view, taken shortly after 

an extremely large flood 

damaged the town of 

Escalante in 1932, shows a 

wide river channel devoid 

of riparian vegetation. The 

bed of this arroyo is several 

meters below the top of its 

former floodplain following 

the downcutting associated 

with another large flood 

in 1909. Fifty-three years 

later (middle image), 

riparian vegetation, 

mostly non-native 

tamarisk and Russian 

olive, has encroached on 

the once barren channel. 

Native coyote willow 

may be present along 

the channel in the center 

distance. By 1999 (bottom 

image), dense riparian 

vegetation, a combination 

of cottonwood and 

non-native tamarisk and 

Russian olive, block the 

view of the background 

cliffs. The channel has 

narrowed considerably 

because the dense 

vegetation trapped 

sediments that developed 

into floodplain terraces. 

(Top photo courtesy of Utah 

State Historical Society.)
The Role of USGS

The invaluable archive of repeat 

photographs maintained by the Desert 

Laboratory Collection provides data 

that is crucial to helping understand 

the effects of climate variation and 

land-use practices on desert environments. Serving as the guardian and 

repository of this collection is only 

one of the many important scientific 

roles that the USGS is playing to help 

administer lands under the protection 

of the Department of the Interior and 

other government agencies. 

Robert H. Webb, Diane E. Boyer, 

Raymond M. Turner, and Stephen H. 

Bullock

References

Bullock, S.H., Martijena, N.E., Webb, R.H., and Turner, R.M., 2005, Twentieth 

century demographic changes in cirio 

and cardón in Baja California: Journal 

of Biogeography, v. 32, p. 127-143.

Griffiths, P.G., Webb, R.H., and Melis, 

T.S., 2004, Initiation and frequency 

of debris flows in Grand Canyon, 

Arizona: Journal of Geophysical 

Research, Surface Processes, v. 109, 

F04002, doi:10.1029/2003JF000077, 

14 p.

Shantz, H.L., and Turner, B.L., 1958, 

Photographic documentation of 

vegetation changes in Africa over a 

third of a century: Tucson, University 

of Arizona, College of Agriculture, 

Report 169, 158 p.

Hastings, J.R., and Turner, R.M. , 1965, The changing mile: Tucson, Univer- sity of Arizona Press, 317 p.

Turner, R.M., Ochung’, H.A., and Turner, J.B., 1998, Kenya’s changing land- scape: Tucson, University of Arizona 

Press, 177 p.

Turner, R.M., Webb, R.H., Bowers, J.E., 

and Hastings, J.R., 2003, The changing 

mile revisited: Tucson, University of 

Arizona Press, 334 p.

Webb, R.H., 1996, Grand Canyon, a cen- tury of change: Tucson, University of 

Arizona Press, 290 p.

Webb, R.H., Leake, S.A., and Turner, 

R.M., 2007, The ribbon of green—

Change in riparian vegetation in the 

Southwestern United States: Tucson, 

University of Arizona Press, 462 p.

Techniques and Storage of Repeat 

Photography Used by the Desert 

Laboratory Collection

Repeat photography techniques used to 

obtain matches of historical images:

•	 Tripod-mounted, large-format film cameras (4 by 5 inch sheet or 120 roll film) 

provide both high resolution and portability, yielding the best possible data.

•	 Film offers superior archival attributes 

to digital images; typically one color and 

two black-and-white negatives and one 

color transparency are made for each 

match.

•	 A variety of fixed lenses are used to 

approximately match the original field of 

view.

•	 Cameras used to take repeat photographs 

are leveled from side to side to allow 

more precise future replications.

•	 Whenever possible, repeat photos match 

the season, date, and even the time of 

day of the original photo.

•	 For each match, notes are taken—(1) 

camera model and its settings, (2) compass azimuth of the view, (3) camera’s 

vertical tilt and height above ground 

level, and (4) view attributes, such 

as plant species, landforms, land-use 

practices, and any special considerations 

required to understand future changes.

•	 Originally, camera station locations were 

mapped on USGS topographic maps; now 

they are also documented using Global 

Positioning System (GPS) receivers. 

Archival techniques:

•	 Negatives and transparencies are stored 

in archival plastic sleeves within archival, 

acid-free paper envelopes. 

•	 A digital database includes a permanent 

“stake” number, assigned to each camera-station location, a brief description of 

the location, geospatial data, the name 

of the original photographer, the date of 

the original photograph, the archive from 

which the image was obtained and the 

accession number, and documentation of 

the number of matches and their dates.

•	 Matches are digitized using high-precision, large-format negative scanners 

and processed with software that allows 

manipulation of image size and quality.

•	 All media associated with camera stations 

are stored according to stake number.

For more information, contact:

Diane E. Boyer

U.S. Geological Survey

520 North Park Avenue, Suite 221

Tucson, Arizona, 85719-5035

Email: deboyer@usgs.gov

This Fact Sheet and any updates to it are available online 

at http://pubs.usgs.gov/fs/2007/3046/

Views of Three Fords 

Rapid on the Green 

River in Desolation 

Canyon, Utah. 

The river, which is 

flowing right to left, 

is relatively wide 

and split into two 

channels in a photo 

taken in 1909 (top 

image). At some time 

in the intervening 

89 years before the 

bottom image was 

taken, a debris flow 

from Three Fords 

Canyon East (behind 

the photographer to 

the right) deposited 

sediment into the 

Green River, greatly 

reducing the width 

of Three Fords Rapid. 

(Top photo courtesy 

of Northern Arizona 

University Cline 

Library.)