Folded cherts of the Franciscan Complex
37.832305°N 122.529003°W

The abandoned quarry displays complex folded radiolarian-rich ribbon cherts with manganese stains associated with hydrothermal activity related to mid-ocean ridge volcanism.   The folding is typical of the accretion process.

Franciscan Assemblage

The Franciscan Assemblage is a geological term for an accreted terrane of heterogeneous rocks found on and near the San Francisco Peninsula. It was named by geologist Andrew Lawson who also named the San Andreas Fault which bounds the Franciscan Assemblage.

• http://en.wikipedia.org/wiki/Franciscan Assemblage
• http://www.nps.gov/goga/forteachers/upload/Geology%20of%20the%20Golden%20Gate%20Headlands%20Field%20Guide.pdf