Golden Gate National Recreation Area, California
by Erica Clites
The Golden Gate National Recreation Area (GGNRA) was established in 1972 to preserve coastal areas around the San Francisco Bay. Many of these coastal rock exposures contain fossils. The Mesozoic-aged Franciscan Complex 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 sedimentary rocks in the late Cenozoic-aged Merced, Millerton and Colma formations are richly fossiliferous and have produced vertebrate fossils including bison, camel, mammoth, mastodon and ground sloth remains. Generations of UC Berkeley students have worked in and near GGNRA, including a recent sediment core study of pollen preserved within Mountain Lake done at the request of the park.
Here is a list of the types of fossils that have been found at the GGNRA to date.1
Jurassic: [may be Cretaceous] radiolarians
Cretaceous: bivalves, belemnites, ammonites, gastropods, marine invertebrates, radiolarians
Paleocene: crustaceans, echinoids, bivalves, gastropods, forams, trace fossils
Pliocene: [may be Pleistocene] insects, echinoids, bivalves, gastropods, plants, invertebrate traces, vertebrate tracks, mammoths, mastodons, horses, camels, sloths, bird (auk)
Pleistocene: pollen, diatoms, mammoth
In the 1950s, UCMP student William Glen studied the type section of the Merced Formation at Seven Mile Beach, now located in the GGNRA. Glen published a list of over 80 types of echinoids, mollusks and mammals present in the Merced Formation. Glen described a new species of bivalve, Spisula mossbeachensis, and designated over 70 invertebrate fossils as characteristic examples, many of which were featured in his 1959 publication and deposited at the UCMP.
Elizabeth Perotti, a student of UCMP curator Dave Lindberg, wrote her 2008 Ph.D. dissertation on rocky intertidal communities. Liz reported on variations in body size of mollusks and limpets as a function of substrate from study sites located within the GGNRA.
Liam Reidy, a Ph.D. student of palynologist Roger Byrne, cored Mountain Lake near the Presidio. The cores record a 2000-year history of environmental changes marked by changes in abundance and types of pollen.
In 2014, UCMP began collaborating with the National Park Service Pacific West Region, working with Angela Evenden of the Californian Cooperative Ecosystem Studies Unit and William Elder of GGNRA. Erica Clites revised and updated a paleontological resource inventory report for GGNRA produced by GeoCorps of America intern Christian Henkel in 2012.
The Multi-Agency Rocky Intertidal Network (MARINe), a consortium of research groups, conducts long-term monitoring of rocky intertidal communities across our coasts and some of the sites included in their study are located within the GGNRA. One of the goals of the monitoring is to track changes in biodiversity through time and they have been monitoring sites for 15 to 25 years. Rosemary Romero has been helping to develop standard procedures for collecting and preserving representative, or "voucher," specimens of target and core algal species observed during MARINe's annual biodiversity surveys. These specimens are examples of the species found at a site at a specific time; they are dried on herbarium paper and will be stored in the Jepson Herbaria with habitat and collection information. Periodic collecting of voucher specimens will provide a record of how the MARINe scientists identified species in the long-term dataset and of the species concepts they used.
In the collections
The University of California Museum of Paleontology houses material from at least 92 localities now located within GGNRA including fossil invertebrates, vertebrates, plants and microfossils. This includes the holotypes of the bivalve Lucina alcatrazis from Alcatraz Island (Anderson 1938; UCMP 10026), the bivalve Spisula mossbeachensis from Moss Beach (Glen 1959; UCMP 37643) and a pinecone (UCMP 20533) found near Mussel Rock described as Pinus lawsoniana by Axelrod (1967).
Note: Collection of fossil material is illegal unless done under a permit from the National Park Service. If you think you have found a fossil on National Park lands, please contact a park representative.
The full text of some of the journal articles may not be accessible to everyone.
Golden Gate National Recreation Area website
Geology of the GGNRA
An article on the coring and history of the Presidio's Mountain Lake
Anderson, F.M. 1938. Lower Cretaceous deposits in California and Oregon. Geological Society of America, Boulder, CO. Special Paper 16. doi:10.1130/SPE16-p1
Axelrod, D.I. 1967. Evolution of the Californian closed-cone pine forest. Pp. 93-149 in R.N. Philbrick (ed.), Proceedings of the Symposium on the Biology of the California Islands: Santa Barbara Botanic Garden, Santa Barbara, CA.
Elder, W.P. 1998. Mesozoic molluscan fossils from the Golden Gate National Recreation Area and their significance to terrane reconstructions for the Franciscan Complex, San Francisco Bay area, California. Pp. 90-94 in V.L. Santucci and L. McClelland (eds.), National Park Service Paleontological Research: National Park Service Technical Report NPS/NRGRD/GRDTR-98/01.
(scroll to page 90)
Elder, W.P., T. Nyborg, J.P. Kenworthy, and V.L. Santucci. 2008. Paleontological Resource Inventory and Monitoring San Francisco Bay Area Network. Natural Resource Technical Report NPS/NRPC/NRTR-2008/078.
Glen, W. 1959. Pliocene and lower Pleistocene of the western part of the San Francisco Peninsula. University of California Publications in Geological Sciences 36(2):147-198.
Perotti, Elizabeth Anne. 2008. Does geology matter? The effects of substratum and substrate properties on temperate rocky intertidal communities. Ph.D. dissertation. University of California, Berkeley.
Reidy, L.M. 2001. Evidence of environmental change over the last 2000 years at Mountain Lake, in the northern San Francisco Peninsula, California. Masters thesis. University of California, Berkeley.
1 Based on a paleontological inventory taken by the National Park Service (2012 data). Fossil inventories for all the NPS fossil parks can be found on The Paleontology Portal's Fossils in the National Parks" module.
Sunset from Stinson Beach photo by outdoorPDK (CC BY-NA-SA 2.0).