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West view of the 2003 sinkhole showing proximity to campus buildings. Sunlight Ski Area is on the left horizon. Roaring Fork River valley is in left middle background below the ski area and in front of first row of ridges. Photo credit: Jon White for the CGS.

Case Study: Colorado Mountain College, Spring Valley

2003-02-04 | CGS Admin

In early February of 2003, a 24-foot-wide (7.5 m) sinkhole spontaneously opened on a soccer field at the Colorado Mountain College (CMC) – Spring Valley campus, about 10 miles (16 km) southeast of Glenwood Springs in Garfield County. The CMC physical plant maintenance staff back-filled the hole with road pavement waste, but the sinkhole subsequently reopened in 2004 and enlarged to about 35 feet (10.5 m) in diameter.

West view of the 2003 sinkhole showing proximity to campus buildings. Sunlight Ski Area is on the left horizon. Roaring Fork River valley is in left middle background below the ski area and in front of first row of ridges. Photo credit: Jon White for the CGS.
West view of the 2003 sinkhole showing proximity to campus buildings. Sunlight Ski Area is on the left horizon. Roaring Fork River valley is in left middle background below the ski area and in front of first row of ridges. Photo credit: Jon White for the CGS.

The site is located near the southern end of Spring Valley. This interesting subsidence feature lies within the Carbondale Collapse Center. Spring Valley, originally a lake, has been interpreted as a drag feature that opened when a large block of basalt-capped redbeds (Maroon Formation) moved laterally, rafting on flowing salt that moved from high-pressure environments under Little Grand Mesa to lower pressure terrain at the axis of the Cattle Creek anticline at the floor of the Roaring Fork River valley. At the southern end of Spring Valley, evaporite dissolution and subsidence has created a complex and chaotic mixing of broken and intact basalt cap rocks, variable bedrock, and depression in-fill of sediments that have been mapped as “collapse debris” in the geologic maps completed by CGS in the late 1990’s.

South close-up view of sinkhole wall showing uniform silt sediments derived from windblown deposits (loess). CMC maintenance staff had started to fill the sinkhole with broken road-pavement waste. Photo credit: Jon White for the CGS.
South close-up view of sinkhole wall showing uniform silt sediments derived from windblown deposits (loess). CMC maintenance staff had started to fill the sinkhole with broken road-pavement waste. Photo credit: Jon White for the CGS.

During the construction of the campus, rolling hills were graded flat to create the soccer field. While basalt blocks occur on the hill top above the field, a large spine of gypsum is exposed in the 25- to 30-foot cut slope that was required to make the field flat. An investigative drill boring at the sinkhole revealed gypsum of the Eagle Valley Evaporite at a depth of 65 feet. This was buried by sediments washed into a natural depression and 30 feet of fairly uniform, mostly reworked windblown sediments (loess) that can be seen in the walls of the sinkhole.

Sample of the loess from the wall of the sinkhole. Photo credit: Jon White for the CGS.
Sample of the loess from the wall of the sinkhole. Photo credit: Jon White for the CGS.

The subsurface void chimneyed up through these sediments from a cavern in the evaporite bedrock below. Just a few months earlier in the summer and fall of 2002, this location was repeatedly driven over by a tractor pulling overlapping gang mowers to cut the grass of the sports fields.

The sinkhole site, nine years later in June of 2012. Photo credit: Colorado Geological Survey.
The sinkhole site, nine years later in June of 2012. Photo credit: Colorado Geological Survey.

The citation section below includes links to a number of the CGS research publications and journal articles related to evaporitic collapse in the region and statewide.

Citations, Categories & Tags

Citations

Kirkham, Robert M., and Robert B. Scott. “Introduction to Late Cenozoic Evaporite Tectonism and Volcanism in West-Central Colorado.” In Late Cenozoic Evaporite Tectonism and Volcanism in West-Central Colorado, by Robert M. Kirkham, Robert B. Scott, and Thomas W. Judkins. Geological Society of America, 2002. https://doi.org/10.1130/0-8137-2366-3.1.
 
Kirkham, Robert M., Randall K. Streufert, and James A. Cappa. “MS-35 Geologic Map of the Shoshone Quadrangle, Garfield County, Colorado.” Geologic, 1:24,000. Map Series. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2008. https://coloradogeologicalsurvey.org/publications/geologic-map-shoshone-quadrangle-garfield-colorado-2.
 
———. “OF-95-04 Geologic Map of the Shoshone Quadrangle, Garfield County, Colorado.” Geologic, 1:24,000. Open File Report. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 1997. https://coloradogeologicalsurvey.org/publications/geologic-map-shoshone-quadrangle-garfield-colorado.
 
Kirkham, Robert M., Randall K. Streufert, H. Thomas Hemborg, and Peter L. Stelling. “OF-14-14 Geologic Map of the Cattle Creek Quadrangle, Garfield County, Colorado.” Geologic, 1:24,000. Open File Reports. Golden, CO: Colorado Geological Survey, 2014. https://coloradogeologicalsurvey.org/publications/geologic-map-cattle-creek-quadrangle-garfield-colorado.
 
Kirkham, Robert M., Randall K. Streufert, Michael J. Kunk, James R. Budahn, Mark R. Hudson, and William J. Perry. “Evaporite Tectonism in the Lower Roaring Fork River Valley, West-Central Colorado.” In Late Cenozoic Evaporite Tectonism and Volcanism in West-Central Colorado, by Robert M. Kirkham, Robert B. Scott, and Thomas W. Judkins. Geological Society of America, 2002. https://doi.org/10.1130/0-8137-2366-3.73.
 
Kirkham, Robert M., and Beth Widmann. “MS-36 Geologic Map of the Carbondale Quadrangle, Garfield County, Colorado.” Geologic, 1:24,000. Map Series. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2008. https://coloradogeologicalsurvey.org/publications/geologic-map-carbondale-quadrangle-garfield-colorado-2.
 
Kirkham, Robert M., and Beth L. Widmann. “OF-97-03 Geologic Map of the Carbondale Quadrangle, Garfield County, Colorado.” Geologic, 1:24,000. Open File Report. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 1997. https://coloradogeologicalsurvey.org/publications/geologic-map-carbondale-quadrangle-garfield-colorado.
 
Kirkham, Robert M., Beth L. Widmann, and Randall K. Streufert. “OF-98-03 Geologic Map of the Leon Quadrangle, Eagle and Garfield Counties, Colorado.” Geologic, 1:24,000. Open File Report. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 1998. https://coloradogeologicalsurvey.org/publications/geologic-map-leon-quadrangle-eagle-garfield-colorado.
 
Lidke, D.J., M.R. Hudson, R.B. Scott, R.R. Shroba, M.J. Kunk, W.J. Perry, R.M. Kirkham, et al. “Eagle Collapse Center: Interpretation of Evidence for Late Cenozoic Evaporite-Related Deformation in the Eagle River Basin, Colorado.” In Late Cenozoic Evaporite Tectonism and Volcanism in West-Central Colorado, by Robert M. Kirkham, Robert B. Scott, and Thomas W. Judkins. Geological Society of America, 2002. https://doi.org/10.1130/0-8137-2366-3.101.
 
Streufert, Randall K. “MS-41 Geologic Map of the Mount Sopris Quadrangle, Garfield and Pitkin Counties, Colorado.” Geologic, 1:24,000. Map Series. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2008. https://coloradogeologicalsurvey.org/publications/geologic-map-mount-sopris-quadrangle-garfield-pitkin-colorado.
 
———. “OF-99-07 Geologic Map of the Mount Sopris Quadrangle, Garfield and Pitkin Counties, Colorado.” Geologic, 1:24,000. Open File Reports. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 1999. https://coloradogeologicalsurvey.org/publications/geologic-map-mt-sopris-quadrangle-garfield-pitkin-colorado.
 
Streufert, Randall K., Robert M. Kirkham, Timothy J. Schroeder II, and Beth L. Widmann. “OF-08-14 Geologic Map of the Dotsero  Quadrangle, Garfield and Eagle Counties, Colorado.” Geologic, 1:24,000. Open File Report. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2009. https://coloradogeologicalsurvey.org/publications/geologic-map-dotsero-quadrangle-garfield-eagle-colorado.
 
Streufert, Randall K., Beth L. Widmann, and Robert M. Kirkham. “MS-39 Geologic Map of the Basalt Quadrangle, Eagle, Garfield, and Pitkin Counties, Colorado.” Geologic, 1:24,000. Map Series. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2008. https://coloradogeologicalsurvey.org/publications/geologic-map-basalt-quadrangle-eagle-garfield-pitkin-colorado-2.
 
———. “OF-98-01 Geologic Map of the Basalt Quadrangle, Eagle, Garfield, and Pitkin Counties, Colorado.” Geologic, 1:24,000. Open File Report. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 1998. https://coloradogeologicalsurvey.org/publications/geologic-map-basalt-quadrangle-eagle-garfield-pitkin-colorado.
 
White, Jonathan L. “Evaporite Karst Subsidence Hazards in Colorado.” In SP-55 History of Hazards Planning in Colorado, Engineering Geology in Colorado – Contributions, Trends, and Case Histories, edited by D. D. Boyer, P. M. Santi, and W. P. Rogers. Special Publication, SP-55. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 2003. https://coloradogeologicalsurvey.org/publications/engineering-geology-colorado-contributions-trends-case-histories.
 
———. “MS-34 Collapsible Soils and Evaporite Karst Hazards Map of the Roaring Fork River Corridor, Garfield, Eagle, and Pitkin Counties, Colorado.” Soil and Karst Hazards, 1:50,000. Map Series. Denver, CO: Colorado Geological Survey, Division of Minerals and Geology, Department of Natural Resources, 2002. https://coloradogeologicalsurvey.org/publications/collapsible-soils-evaporite-karst-hazards-roaring-fork-river-garfield-eagle-pitkin-colorado.
 
———. “OF-12-02 Colorado Map of Potential Evaporite Dissolution and Evaporite Karst Subsidence Hazards.” Evaporite and Karst, 1:24,000. Open File Reports. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 2012. https://coloradogeologicalsurvey.org/publications/evaporite-dissolution-karst-subsidence-hazard-map-colorado.
 

Categories

Geology, Hazards

Tags

evaporite, Garfield, geologic hazards, geology, Gypsum, hazards, karst, Maroon, Roaring Fork, RockTalk, sinkholes, subsidence