page_title: Marin Headlands
section_title: Geology
hierarchical_section_title: Marin Headlands / Geology
caption_attribution_description: English: San Francisco, the Golden Gate Bridge, and the Marin Headlands, from a commercial airliner in 2018.
context_page_description: The Marin Headlands is a hilly peninsula at the southernmost end of Marin County, California, United States, located just north of San Francisco across the Golden Gate Bridge, which connects the two counties and peninsulas. The entire area is part of the Golden Gate National Recreation Area. The Headlands are famous for their views of the Bay Area, especially of the Golden Gate Bridge.
context_section_description: The Marin Headlands are underlain by fascinating geological formations created by the accretion of oceanic sediments from the Pacific Plate onto the North American Plate. The process of subduction of ocean floor, followed by tectonic underplating to the underside of the over-riding plate, was first described here by Clyde Wahrhaftig in 1984. The primary rock types of the Marin Headlands include graywacke sandstone, radiolarian chert, serpentinite, pillow basalts, and shale. These rocks began their migration over one hundred million years ago from as far south as present-day Los Angeles. The erosion of the hillsides and construction activities during the military era have exposed some dramatic examples of these rock types for easy viewing, and the folding caused by tectonic action is visually evident in many places throughout the Headlands.
  Marin Headlands is one of the featured field trips found in the Streetcar 2 Subduction online field trip guide series released in December 2019 by the American Geophysical Union.
caption: Aerial view of the Marin Headlands, Golden Gate Bridge, and San Francisco.
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