HR: 0800h
AN: ED41A-0076    [Abstracts]
TI: Geologic Investigations of the Marin Headlands, California
AU: * DeAraujo, J
EM: sfrocks@sfsu.edu
AF: The Urban School of San Francisco, 1563 Page Street, San Francisco, CA 94117, United States
AU: Jones, D
EM: sfrocks@sfsu.edu
AF: John O'Connell High School of Technology, 2355 Folsom Street, San Francisco, CA 94110, United States
AU: Matic, M
EM: sfrocks@sfsu.edu
AF: Phillip and Sala Burton Academic High School, 400 Mansell Street, San Francisco, CA 94134, United States
AU: Yue, J
EM: sfrocks@sfsu.edu
AF: City College of San Francisco, 50 Phelan Avenue, San Francisco, CA 94112, United States
AU: Bailey, C
EM: sfrocks@sfsu.edu
AF: San Francisco State University, Department of Geosciences, 1600 Holloway Avenue, San Francisco, CA 94132, United States
AU: Scherer, H
EM: sfrocks@sfsu.edu
AF: Stanford University, Department of Geological & Environmental Sciences, 450 Serra Mall, Stanford, CA 94305, United States
AB: The Marin Headlands has a unique geology formed by a convergent plate boundary, where the Farallon plate subducted beneath the North American plate. This process formed igneous, sedimentary, and metamorphic rocks. We can see these rocks today because the San Andreas fault, which formed when the North American and Pacific plates collided, pushed up the rocks. We examined the Headlands to learn more about the rocks and their structure. We hiked around many trails, including the Kirby Cove trail. While on the trails we observed the rocks we found and identified four units. The four units that we observed were (1) chert, which is sedimentary, layered, and very-fine grained; (2) greywacke, which is also sedimentary, light brown colored, with a medium to coarse grain size; (3) basalt and (4) diabase which are both meta-igneous, green, and have crystals (the difference being that basalt is extrusive with smaller crystals and diabase is intrusive with larger crystals). While gathering information on the types of rocks, we made a geologic map including the strike and dip of the rocks. We interpret the rocks at the Marin Headlands to represent ancient oceanic crust upon which chert was deposited. The greywacke was deposited later, as the oceanic crust got close to the continental margin. All of these rocks were extensively folded and fractured as they were added to the continent as part of the material in a subduction zone. In conclusion, the Marin Headlands is a very special place to study a part of the diverse geology of California.
UR: http://sf-rocks.sfsu.edu
DE: 6630 Workforce
SC: Education and Human Resources [ED]
MN: 2007 Fall Meeting