Geologic Wonders of the Hart(sel) of South Park
June 25, 2017
Leader: Peter Barkmann, Colorado Geological Survey
This field trip explored the Hartsel area, starting with a look at the Precambrian granodiorite and its cross-cutting pegmatite sheets. We then saw the onlap of the Late Paleozoic central Colorado trough sediments onto the ancestral Front Range highland and the Garo Sandstone healing cover. Our transect then looked at the Laramide synorogenic South Park Formation with its complex stratigraphic story. Last but not least was the Neogene transformation from compression to extension with a fascinating story of Neogene tectonic closure of intermontane fluvial systems and progressive integration and incision driven by middle to late Pleistocene glacial episodes.
The all-day trek around Hartsel visited about 12 sites, with most requiring minimal off road scrambling. There was an overnight option to stay at the historic Hartsel Springs Ranch about 2 miles east of town at the confluence of the South and Middle Forks South Platte River. Peter Barkmann’s field trip notes and a map of the sites visited are attached. Please respect private property when visiting these sites. (The barite mine is on private property.)