Quaternary glacial and slope-failure deposits of the Crested Butte area, Gunnison County, Colorado
— Charles H. Robinson and Peter A. Dea

During the Quaternary Period, the region near Crested Butte, Gunnison County, Colorado was subjected to alpine glaciation. Glacial, periglacial and alpine processes have produced surficial deposits that are involved in the development of the area. The proposed molybdenum mine on Mount Emmons and expansion of the recreational industry have imposed strong development pressures. The genesis of the surficial deposits, on which much of the development will occur, has a profound impact on the engineering considerations for development.

 

Feasibility studies of the Mount Emmons molybdenum deposit by AMAX, Inc. are being conducted in the area around Crested Butte, Colorado. Engineering and environmental geologic mapping at scales ranging from 1:24,000 to 1:2,400 has been conducted over a three-year period beginning in June 1978 by Charles S. Robinson and Associates, now Converse Ward Davis Dixon, Inc., as part of these feasibility studies (fig. 1). The study of the surficial deposits led to a basic understanding of the late Pleistocene and Recent geologic history of the region.

 

Bedrock geologic studies of the area were conducted by Gaskill and others (1976, 1977) of the U.S. Geological Survey and by exploration geologists with Climax Molybdenum Company and AMAX, Inc. Geologic hazards were recognized by Soule (1976) of the Colorado Geologic Survey.