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years ago during the Laramide orogeny. Sediments from <br />surrounding highlands were deposited in the basin, <br />accumulating to a thickness of as much as 9000 feet by the <br />lower Eocene epoch, when subsidence ceased. Regional uplift <br />occurred in the Late Tertiary, and erosion of the area has <br />continued since (Young and Young 1977:43-46). <br />The study area lies in the bottom of Debeque Canyon. The <br />Hunter Canyon Formation is the massive cliff-forming sandstone <br />that frames the Colorado River drainage through Debeque <br />Canyon. The Mount Garfield Formation and Sego Sandstone <br />underlies the Hunter Canyon Formation and forms the bedrock of <br />the project area. <br />The region is characterized as having a cool desert <br />climate. Precipitation ranges between 10 and 14 inches, <br />although the surrounding mountain areas may receive up to 20 <br />inches. Temperatures range from about 95 degrees F in the <br />summer to -5 degrees F during January. A frost-free period of <br />about 160 days is the maximum (USDA SCS 1978b:401). <br />Paleoenvironmental data for the area are scant, but it is <br />generally agreed that gross climatic conditions have remained <br />fairly constant over the last 12,000 years. Still, changes in <br />effective moisture and cooling/warming trends probably <br />affected the prehistoric occupation of the area. <br />• Elevation of the study area ranges between 5020 and 5120 <br />feet, which falls within the Upper Sonoran zone. Vegetation <br />is sparse and includes juniper trees, grasses and desert <br />shrubs. Heavy surface disturbance was noted over about 50$ of <br />the project area. Ground visibility averages about 90 percent <br />in the project area. <br />Regional faunal inhabitants include game species such as <br />elk, deer, and cottontails. Predators--coyotes, mountain <br />lions, bobcats, weasels, and raptors--are also common. <br />Files Search <br />A files search made through the BLM Grand Junction Area <br />Office on 27 August 1993 showed no cultural resources were <br />previously recorded in the study area. However, regional <br />research suggests nearly continuous human occupation of west- <br />central Colorado for the past 12,000 years. Evidence of the <br />Paleoindian Tradition, the Archaic Tradition, Formative <br />Cultures, and Protohistoric/Historic Utes has been found. <br />Historic records suggest occupation or use by Euroamerican <br />trappers, settlers, miners, and ranchers as well. Overviews <br />4 <br />