OF-02-05 Geologic Map of the Cheyenne Mountain Quadrangle, El Paso County, Colorado

Describes the geologic setting, geologic hazards, and mineral resource potential of this 7.5 minute quad located in the southern suburbs of Colorado Springs and mostly west of Interstate-25. Includes descriptions of map units, structural geology, correlation of map units, cross-sections and an oblique view. (1:24,000). A 30-page booklet accompanies the map. Digital PDF download. OF-02-05D

From the Author’s Notes:

The objective of this publication is to provide geologic maps in areas impacted by residential and other infrastructure development, especially those areas containing significant geologic hazards and mineral and construction material resources. This map is intended to benefit engineering companies, government planners, resource developers, and other interested citizens.

Landslides and related features such as earthflows and soil creep are common in the Colorado Springs area because the Pierre Shale underlies most of the urbanized area east of the mountain front. Shales in the Niobrara Formation, Carlile Shale, Graneros Shale, and Morrison Formation also are prone to the same types of earth failure, but are less significant because they underlie a much smaller area. Within the Cheyenne Mountain quadrangle, virtually all significant slopes underlain by the Pierre Shale have flowed or slid, particularly along the eroded margins of pediments.
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Because the quadrangle underlies not only the southern side of the rapidly growing suburbs of Colorado Springs but also two military bases, landslides have the potential to create severe economic hardships on public facilities and private homeowners if not correctly identified, analyzed, and engineered. In those places in the mapped area where a significant cover of Quaternary deposits overlie the Pierre, construction has little influence on the inherent stability of the slope.