OF-22-09 Geochronology and Geomorphic Mapping to Estimate Debris-flow Depositional Ages and Recurrence Intervals Along State Highways 145 and 62, San Miguel County, Colorado


Debris-flows are a common problem in the mountainous areas of the state, and this project—requested and funded by the Colorado Department of Transportation (CDOT)—explores both the geochronology and geomorphology of debris-flow fans along two major access roads in the San Juan Mountains in the south-west part of the state. Digital PDF download. OF-22-09D

From the Scope of Work:

This project was developed in response to the request by CDOT and San Miguel County for 1:24,000-scale mapping and geochronology of debris-flow deposits along State Highway 145 between Norwood and Telluride, and Highway 62 from the intersection of State Highways 52 and 145 to roughly halfway to Ridgway. Detailed mapping and age dating of debris-flow fans are helpful in hazard analysis and identification of sites where more intensive geotechnical investigations are necessary. These data can be used to estimate recurrence intervals, magnitude of events, and channel migration history. The results of this study are anticipated to be part of a larger effort to help San Miguel County develop a debris-flow early warning system by better understanding the history of debris-flow events in the canyons.