The La Brea Tar Pits constitute an active paleontological research site located in urban Los Angeles, California, United States. Hancock Park was established around a cluster of tar pits formed by natural asphalt (also referred to as asphaltum, bitumen, pitch or brea in Spanish) that has continuously seeped upward from the ground for tens of thousands of years. Over centuries, these asphalt deposits trapped numerous prehistoric animals, preserving their skeletal remains. The site is home to the George C. Page Museum, dedicated to the ongoing excavation, research and public display of preserved specimens. The La Brea Tar Pits is recognized as a registered National Natural Landmark. The museum closed on July 7, 2026 for a 2-year renovation.
Formation
Tar pits are composed of heavy oil fractions, called gilsonite, which seep from the earth as oil. Crude oil seeps up along the 6th Street Fault from the Salt Lake Oil Field, which underlies much of the Fairfax District north of Hancock Park. The oil reaches the surface and forms pools, becoming asphalt as the lighter fractions of the petroleum biodegrade or evaporate. The asphalt then normally hardens into stubby mounds, which can be seen in several areas of the park. This seepage has been happening for tens of thousands of years, during which the asphalt sometimes formed a deposit thick enough to trap animals. The deposit then became covered with water, dust, and leaves. Animals wandered in, became trapped, and died. Predators entered to eat the trapped animals and then also become stuck, a phenomenon called a "predator trap". As the bones of a dead animal sank, the asphalt would soak into them, turning them dark-brown or black in color. Lighter fractions of petroleum evaporated from the asphalt, leaving a more solid substance, which then encased the bones. Dramatic fossils of large mammals have been extricated, and the asphalt also preserves microfossils: wood and plant remnants, rodent bones, insects, mollusks, dust, seeds, leaves, and pollen grains. Examples of these are on display in the George C. Page Museum. Radiometric dating of preserved wood and bones has given an age of 38,000 years for the oldest known material from the La Brea seeps.
History
The Chumash and Tongva people used tar from the pits to build plank boats by sealing planks of California redwood trunks that drifted into the Santa Barbara Channel, which they used to navigate the California coastline and Channel Islands. The Portolá expedition, a group of Spanish explorers led by Gaspar de Portolá, made the first written record of the tar pits in 1769. Father Juan Crespí wrote,
While crossing the basin, the scouts reported having seen some geysers of tar issuing from the ground like springs; it boils up molten, and the water runs to one side and the tar to the other. The scouts reported that they had come across many of these springs and had seen large swamps of them, enough, they said, to caulk many vessels. We were not so lucky ourselves as to see these tar geysers, much though we wished it; as it was some distance out of the way we were to take, the Governor [Portolá] did not want us to go past them. We christened them Los Volcanes de Brea [the Tar Volcanoes].
Harrison Rogers, who accompanied Jedediah Smith on his 1826 expedition to California, was shown a piece of the solidified asphalt while at Mission San Gabriel, and noted in his journal, "The Citizens of the Country make great use of it to pitch the roofs of their houses". The La Brea Tar Pits and Hancock Park were formerly part of the Mexican land grant of Rancho La Brea. For some years, tar-covered bones were found on the property but were not initially recognized as fossils because the ranch had lost various animals—including horses, cattle, dogs, and even camels—whose bones closely resemble several of the fossil species. Initially, they mistook the bones in the pits for the remains of pronghorn or cattle that had become mired. The original Rancho La Brea land grant stipulated that the tar pits be open to the public for the use of the local Pueblo. There were originally more than 100 separate pits of tar (or asphaltum) but most of those have been filled in with rock or dirt since settlement, leaving about a dozen accessible from ground level. In 1886, the first excavation for land pitch in the village of La Brea was undertaken by Messrs Turnbull, Stewart & co..
Excavations
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