OF-22-08 Geologic Map of the Windsor Quadrangle, Larimer and Weld Counties, Colorado


The purpose of this publication is to describe the geology, mineral and groundwater resources, and geologic hazards of the Windsor 7.5-minute quadrangle. It is a continuation of field mapping work on the northern Front Range of Colorado where the CGS has mapped multiple quadrangles, this one covering the area around the town of Windsor. CGS Geologists Stephen Keller and Alex Marr completed the field work on this project during the mapping seasons of 2021-22. Digital ZIP download. OF-20-08D

Summary from the the Geologic History:

The Windsor quadrangle, situated in the northern part of the Colorado Piedmont, features relatively low topographic relief with a 94-meter variance between its highest and lowest points. Notable elongated outcrop areas of weathered bedrock are observed along the dissected southwest side of the Cache la Poudre River valley. While fresh bedrock is mainly found in lower gravel pit faces in the Big Thompson River valley, unconsolidated Quaternary deposits cover most of the quadrangle with few natural exposures along river cut banks. The landscape is primarily characterized by a broad upland swath bordered by the valleys of the Big Thompson River and Cache la Poudre River, drained by southeast-flowing rivers and tributary streams, and shaped by late Neogene and Quaternary geomorphic processes.

The Windsor quadrangle hosts seven active construction permits (as of 2021), primarily for sand and gravel extraction, distributed between Larimer and Weld counties along the Cache la Poudre River and Big Thompson River valleys. These pits are located in floodplain and valley-fill deposits and are discernible on lidar images excavated in alluvial sand and gravel. Additionally, the quadrangle lies within the Wattenberg field, a significant oil and gas producing area, with infrastructure concentrated in the rural upland between the river valleys. The quadrangle also experiences geologic hazards, including the potential susceptibility of eolian sediments to collapse and induced seismic activity attributed to wastewater injection operations, as seen in nearby areas such as Greeley.