Golden Gate National Recreation Area Fossil Hunting Guide
Image: Radomianin (CC BY-SA 4.0)
The Golden Gate National Recreation Area, located in San Francisco, California, is a treasure trove for paleontology enthusiasts.
The Golden Gate National Recreation Area, located in San Francisco, California, is a treasure trove for paleontology enthusiasts. The park is home to a wide diversity of marine and terrestrial fossils, including plants and animals. However, only a few of the rock units in the park are known to produce fossils, and most are marine invertebrates and microfossils. The park's geology is also fascinating, with the Presidio showcasing serpentinite that was formed deep in a subduction and then pushed up to the surface along fault zones. The Marin Headlands contain abundant exposures of a rock of biological origin, radiolarian chert, which forms nearly all of the ridge tops and summits in the Headlands due to its resistance to weathering. The park also contains younger rocks linked to sea level rise and fall during past glacial periods.
The Merced Formation forms the sea cliffs at Fort Funston and is composed of fossil-rich beds of sand and clay laid down during the late Pliocene and Pleistocene epochs. The Colma Formation dates back a mere 100,000 years and records a time of high sea level developed during the last warm interglacial period before our present one. These rocks are locally covered by recent sand dunes formed from 5,000 to 8,000 years ago as sea level stabilized following the last glacial period that peaked around 19,000 years ago. The Mesozoic-aged Franciscan Complex in the park contains few macrofossils but contains microscopic fossils, radiolarians, and, together with rare macrofossils, are of great importance in dating these terranes composed of oceanic rocks. The park is accessible to the public, and visitors are encouraged to explore and discover the rich geological and paleontological history it offers. However, fossil hunting is not permitted, and all fossils must be left undisturbed for others to enjoy.
Remember that this is a National Park and you should inform yourself of the appropriate permissions and restrictions of National Park land when it comes to fossil hunting.
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