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Geologic map of the Bailey 30' x 60' quadrangle, North-Central Colorado

November 21, 2011

The Bailey, Colo. 1:100,000-scale quadrangle lies within two physiographic and geologic provinces in central Colorado: 1) the Front Range and 2) South Park. Most of the Front Range is composed of Proterozoic rocks ranging in age from 1,790 Ma to 1,074 Ma. Along the eastern flanks and within the Denver Basin, sedimentary rocks ranging from Pennsylvanian to Cretaceous are deformed and steeply tilted to the east. Upper Cretaceous through Paleocene rocks were deposited in the foreland (that is, the Front Range eastern flank) and hinterland (that is, South Park) of this thrust and reverse fault system developed during the Late Cretaceous to Paleocene Laramide orogeny. Within South Park, rocks range in age from Pennsylvanian to Miocene with Quaternary deposits indicating tectonic subsidence of the basin. These rocks record five major geologic episodes: 1) the Paleozoic Anasazi uplift that formed the Ancestral Rockies, 2) the Late Cretaceous to Paleocene Laramide orogeny, 3) widespread Eocene to Oligocene volcanism, 4) Oligocene-Quaternary tectonics, and 5) Quaternary glacial episodes.

Publication Year 2011
Title Geologic map of the Bailey 30' x 60' quadrangle, North-Central Colorado
DOI 10.3133/sim3156
Authors Chester A. Ruleman, Robert G. Bohannon, Bruce Bryant, Ralph R. Shroba, Wayne R. Premo
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Scientific Investigations Map
Series Number 3156
Index ID sim3156
Record Source USGS Publications Warehouse
USGS Organization Geology and Environmental Change Science Center