Unnamed stone occurrence , Five Brooks, Marin Co., California, USA
|Latitude & Longitude (WGS84):||37° 59' 4'' North , 122° 44' 13'' West|
|Latitude & Longitude (decimal):||37.98472,-122.73722|
|Köppen climate type:||Csb : Warm-summer Mediterranean climate|
A stone (crushed/broken) deposit located in the S sec. 27, T2N, R8W, MDM, 2.5 km (8,200 feet) SE of Five Brooks on federal land administered by the National Park Service (Golden Gate National Recreation Area). MRDS database stated accuracy for this location is 1,000 meters. Section number questionable.
Local rocks include Miocene marine rocks.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
No minerals currently recorded for this locality.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
0 - 2.588 Ma
Age: Pleistocene (0 - 2.588 Ma)
Description: Poorly sorted sandstone and conglomerate; poorly indurated; lens-shaped bedding irregularly present, crossbedding common; locally contains small wood fragments along San Andreas fault zone; includes thinly laminated siltstone or claystone with interbedded gravels
Reference: Blake, M.C. Jr., R.W. Graymer, and D.L. Jones. Geologic map and map database of parts of Marin, San Francisco, Alameda, Contra Costa, and Sonoma Counties, California. U.S. Geological Survey Miscellaneous Field Studies MF 2337. 
|Pliocene - Oligocene|
2.588 - 33.9 Ma
|Miocene marine rocks|
Age: Cenozoic (2.588 - 33.9 Ma)
Stratigraphic Name: Agua Sandstone Member; Alferitz Formation; Altamira Shale Member; Antelope Shale Member; Big Blue Serpentinous Member; Branch Canyon Formation; Briones Formation; Button Bed Sandstone Member; Capistrano Formation; Carneros Sandstone Member; Castaic Formation; Cierbo Sandstone; Claremont Shale; Devilwater Silt-Gould Shale Member; Escudo Sandstone; Fish Creek Gypsum Member; Freeman Silt; Gallaway Beds; Hambre Sandstone; Hannah Formation; Hercules Shale Member; Jewett Sand; La Vida Member; Malaga Mudstone Member; McDonald Shale; McLure Shale Member; Media Shale Member; Modelo Formation; Monterey Formation; Neroly Formation; Olcese Sand; Oso Member; Oursan Sandstone; Painted Rock Sandstone Member; Pismo Formation; Pleito Formation; Point Arena Beds; Point Sal Formation; Puente Formation; Pullen Formation; Quail Lake Formation; Reef Ridge Shale; Rincon Shale; Rodeo Shale; Round Mountain Silt; Salinas Shale; Salt Creek Shale Member; Saltos Shale Member; Sandholdt Shale; San Onofre Breccia; San Pablo Group; Santa Margarita Formation; Santos Shale Member; Sisquoc Formation; Sobrante Sandstone; Soda Lake Sandstone Member; Soda Lake Shale Member; Soquel Member Split Mountain Formation; Sycamore Canyon Member; Temblor Formation; Tequepis Sandstone; Tice Shale; Topanga Formation; Twisselman Sandstone Member; Valmonte Diatomite Member; Vaqueros Formation; Vedder Sand; Whiterock Bluff Shale Member; Wimer Formation; Yorba Member
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
|Cretaceous - Jurassic|
66 - 201.3 Ma
Age: Mesozoic (66 - 201.3 Ma)
Description: Sheared shale and sandstone contains hard tectonic inclusions predominantly of greenstone, chert, and graywacke and variably resistant masses of graywacke, greenstone, and serpentinite (Blake and others, 1974). This sheared rock or melange that crops out east of Tomales Bay is assigned to the Central tectonostratigraphic terrane of Blake and others (1984) of Late Jurassic and Early Cretaceous age (Wahrhaftig and Wakabayashi, in Wahrhaftig and Sloan, 1989). Graywacke and interbedded shale with minor conglomerate of the San Bruno Mountain terrane form Bolinas Ridge southeast of Point Reyes Station. East of Point Reyes Station this sandstone and shale locally has been hydrothermally altered (Blake and others, 1974). Limestone is present at Olema, indicating that the Franciscan in this area belongs to the Permanente terrane.
Reference: J. C. Clark and E. E. Brabb. Geology of Point Reyes National Seashore and Vicinity, California: A Digital Database. USGS Open-File Report 97-456.