Natural oil seeps have long been observed in southern California.  The most famous petroleum seep locality is the La Brea Tar Pits ("the the tar tar" pits; aka Rancho La Brea), located along Wilshire Boulevard in the Salt Lake Oil Field just west of downtown Los Angeles & just east of Beverly Hills & just southwest of Hollywood.



La Brea Tar Pits & Page Museum.  The large body of water at bottom is the Lake Pit.

(Satellite photo provided by Sanborn & Google Earth)



La Brea is most famous for its abundant Late Pleistocene & early Holocene fossil and subfossil biotas.  Hundreds of thousands of Ice Age fossils have been excavated from asphalt-impregnated sediments here.  Fossil organisms retrieved from the La Brea Tar Pits range in age from 9 ky to 40 ky and include mammals (horses, dire wolves, saber-toothed tigers, American lions, mammoths, ground sloths, buffalo, etc.; 58 spp.), birds (138 spp.), reptiles (24 spp.), amphibians (6 spp.), fish (3 spp.), molluscs (bivalves, aquatic gastropods & pulmonate gastropods; 56 spp.), various arthropods (168 spp.), diatoms (75 spp.), and plants (80 spp.).  Even a partial human skeleton has been recovered.



La Brea Tar Pits (above & below) - bubbles of methane gas (CH4) surfacing in a small natural petroleum seep.


La Brea Tar Pits


La Brea Tar Pits



La Brea Tar Pits - this is part of the "Lake Pit", an old fossil excavation pit now filled with water and some degraded oil/tar.


La Brea Tar Pits - large bubble of natural methane gas (CH4) surfacing at the Lake Pit.



La Brea Tar Pits - active fossil excavation by Page Museum workers at “Pit 91” back in 1999.  Fossil collection is typically done during the warmest parts of summer.  Cooler temperatures at other times of year result in thickened & hardened asphalt deposits.



La Brea Tar Pits - model reconstruction by the Carnegie Museum of Natural History (Pittsburgh, Pennsylvania, USA).



Mostly synthesized from info. provided by the Page Museum (George C. Page Museum of La Brea Discoveries, LACM - Los Angeles County Natural History Museum).



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