LA BREA TAR PITS
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).