Reverse fault at Scorpion Anchorage, Santa Cruz Island, California, USA
Example of crustal convergence in the western Transverse Ranges
Visitors to Scorpion Anchorage on Santa Cruz Island (SCI), California, USA will often ask about a colorful rock outcrop on the nearby point just to the west of the pier. A reverse fault displaces reddish-brown Santa Cruz Island Volcanics over whitish Monterey Formation. The fault surface dips ~40 degrees to the south (left as seen from the pier). Santa Cruz Island is within the western Transverse Ranges, a geologic province with active north-south crustal convergence. The reverse fault at Scorpion Anchorage is in response to the crustal-shortening resulting from the crustal convergence.
Reverse fault at Scorpion Anchorage, September 14, 2022. Video link,
Also, check out our recent Santa Cruz Island Geology Field Guide: Santa Cruz Island field trip: Geology, history, and research opportunities, Davis, T.L., Behl, R.J., O’Sullivan, K.M., Raskin, S., and Bryne, S., 2020, in Heermance, R.V., and Schwartz, J.J., eds., From the Islands to the Mountains, View of Geologic Excursions in Southern California: Geological Society of America Field Guide 59, p. 115–163,
https://pubs.geoscienceworld.org/gsa/books/book/2279/From-the-Islands-to-the-Mountains-A-2020-View-o
THOMAS L. DAVIS PHD PG & ASSOCIATES LEAD AND ORGANIZE GEOLOGIC FIELD TRIPS IN THE SOUTHWESTERN USA AND BAJA CALIFORNIA FOR ORGANIZATIONS, COMPANIES, AND INDIVIDUALS, CONTACT US AT tldavisgeo@gmail.com or geologicmapsfoundation@gmail.com
Other geologic sources: https://www.nps.gov/chis/learn/nature/geologicformations.htm