La Brea Tar Pits comprise an active paleontological research site in urban

Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

. Hancock Park was formed around a group of

tar pit Tar pits, sometimes referred to as asphalt pits, are large Bitumen, asphalt deposits. They form in the presence of petroleum, which is created when decayed organic matter is subjected to pressure underground. If this crude oil seeps upward via ...

s where natural

asphalt Asphalt most often refers to: * Bitumen, also known as "liquid asphalt cement" or simply "asphalt", a viscous form of petroleum mainly used as a binder in asphalt concrete * Asphalt concrete, a mixture of bitumen with coarse and fine aggregates, u ...

(also called asphaltum, bitumen, or pitch; ''brea'' in Spanish) has seeped up from the ground for tens of thousands of years. Over many centuries, the bones of trapped animals have been preserved. The George C. Page Museum is dedicated to researching the tar pits and displaying specimens from the animals that died there. "La Brea Tar Pits" is a registered

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best e ...

Formation

Tar pits are composed of heavy oil fractions, called gilsonite, which seep from the earth as oil.

Crude oil Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring u ...

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, become 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 A fraction (from , "broken") represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight-fifths, thre ...

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 Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to Chronological dating, date materials such as Rock (geology), rocks or carbon, in which trace radioactive impurity, impurities were selectively incorporat ...

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 The Tongva ( ) are an Indigenous peoples of California, Indigenous people of California from the Los Angeles Basin and the Channel Islands of California, Southern Channel Islands, an area covering approximately . In the precolonial era, the peop ...

people used tar from the pits to build plank boats by sealing planks of

California redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995: 606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coast ...

trunks and pieces of driftwood from the

Santa Barbara Channel The Santa Barbara Channel is a portion of the Southern California Bight and separates the mainland of California from the northern Channel Islands. It is generally south of the city of Santa Barbara, and west of the Oxnard Plain in Ventura Co ...

, which they used to navigate the California coastline and

Channel Islands The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. They are divided into two Crown Dependencies: the Jersey, Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, ...

. The Portolá expedition, a group of Spanish explorers led by

Gaspar de Portolá Captain Gaspar de Portolá y Rovira (January 1, 1716 – October 10, 1786) was a Spanish Army officer and colonial administrator who served as the first List of governors of California before 1850, governor of the Californias from 1767 to 1770 ...

, made the first written record of the tar pits in 1769. Father

Juan Crespí Juan Crespí, OFM (Catalan language, Catalan: ''Joan Crespí''; 1 March 1721 – 1 January 1782) was a Franciscan missionary and explorer of The Californias, Las Californias. Biography A native of Majorca, Crespí entered the Franciscan ord ...

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 ortoládid not want us to go past them. We christened them ''Los Volcanes de Brea'' he Tar Volcanoes.

Harrison Rogers, who accompanied

Jedediah Smith Jedediah Strong Smith (January 6, 1799 – May 27, 1831) was an American clerk, transcontinental pioneer, frontiersman, hunter, trapper, author, cartography, cartographer, mountain man and explorer of the Rocky Mountains, the Western Unit ...

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 Pueblo refers to the settlements of the Pueblo peoples, Native American tribes in the Southwestern United States, currently in New Mexico, Arizona, and Texas. The permanent communities, including some of the oldest continually occupied settlement ...

. 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.''. La Brea SW01

Excavations

Union Oil geologist W. W. Orcutt is credited, in 1901, with first recognizing that fossilized prehistoric animal bones were preserved in pools of asphalt on the Hancock ranch. In commemoration of Orcutt's initial discovery, paleontologists named the La Brea coyote (''Canis latrans orcutti'') in his honor. John C. Merriam of the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...

led much of the original work in this area early in the 20th century. Contemporary excavations of the bones started in 1913. In the 1940s and 1950s, public excitement was generated by the preparation of previously recovered large mammal bones. A subsequent study demonstrated the fossil vertebrate material was well preserved, with little evidence of bacterial degradation of bone protein. They are believed to be some 10–20,000 years old, dating from the Last Glacial Period. On February 18, 2009, George C. Page Museum announced the 2006 discovery of 16 fossil deposits that had been removed from the ground during the construction of an underground parking garage for the

Los Angeles County Museum of Art The Los Angeles County Museum of Art (LACMA) is an art museum located on Wilshire Boulevard in the Miracle Mile vicinity of Los Angeles. LACMA is on Museum Row, adjacent to the La Brea Tar Pits (George C. Page Museum). LACMA was founded in 1961 ...

next to the tar pits. Among the finds are remains of a saber-toothed cat, dire wolves, bison,

horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 milli ...

, a giant

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. They varied widely in size with the largest, belonging to genera '' Lestodon'', ''Eremotherium'' and ''Megatherium'', being around the size of elephants. ...

, turtles, snails, clams, millipedes, fish, gophers, and an

American lion The American lion (''Panthera atrox'' (), with the species name meaning "savage" or "cruel", also called the North American lion) is an extinct pantherine cat native to North America during the Late Pleistocene from around 129,000 to 12,800 y ...

. Also discovered is a nearly intact mammoth skeleton, nicknamed Zed; the only pieces missing are a rear leg, a vertebra, and the top of its skull, which was sheared off by construction equipment in preparation to build the parking structure. These fossils were packaged in boxes at the construction site and moved to a compound behind Pit 91, on Page Museum property, so that construction could continue. Twenty-three large accumulations of tar and specimens were taken to the Page Museum. These deposits are worked on under the name "Project 23". As work for the public transit D Line is extended, museum researchers know more tar pits will be uncovered, for example near the intersection of Wilshire and Curson. In an exploratory subway dig in 2014 on the Miracle Mile, prehistoric objects unearthed included geoducks, sand dollars, and a from a pine tree, of a type now found in

Central California Central California is generally thought of as the middle third of the U.S. state of California, north of Southern California (which includes Los Angeles and San Diego) and south of Northern California (which includes San Francisco and San Jose, ...

's woodlands.

George C. Page Museum

In 1913, George Allan Hancock, the owner of Rancho La Brea, granted the

Natural History Museum of Los Angeles County Nature is an inherent character or constitution, particularly of the ecosphere or the universe as a whole. In this general sense nature refers to the laws, elements and phenomena of the physical world, including life. Although humans are par ...

exclusive excavation rights at the Tar Pits for two years. In those two years, the museum was able to extract 750,000 specimens at 96 sites, guaranteeing that a large collection of fossils would remain consolidated and available to the community. Then in 1924, Hancock donated to Los Angeles County with the stipulation that the county provide for the preservation of the park and the exhibition of fossils found there. The George C. Page Museum of La Brea Discoveries, part of the Natural History Museum of Los Angeles County, was built next to the tar pits in Hancock Park on

Wilshire Boulevard Wilshire Boulevard ( wɪɫ.ʃɚ is a prominent boulevard in the Los Angeles area of Southern California, extending from Ocean Avenue (Santa Monica), Ocean Avenue in the city of Santa Monica, California, Santa Monica east to Grand Avenue (Lo ...

. It was named for a local philanthropist. Construction began in 1975, and the museum opened to the public in 1977. The area is part of urban Los Angeles in the Miracle Mile District. The museum tells the story of the tar pits and presents specimens excavated from them. Visitors can walk around the park and see the tar pits. On the grounds of the park are life-sized models of prehistoric animals in or near the tar pits. Of more than 100 pits, only Pit 91 is still regularly excavated by researchers and can be seen at the Pit 91 viewing station. In addition to Pit 91, the one other ongoing excavation is called "Project 23". Paleontologists supervise and direct the work of volunteers at both sites. As a result of a design competition in 2019, the Natural History Museum of Los Angeles County chose Weiss/Manfredi over Dorte Mandrup and

Diller Scofidio + Renfro Diller has several uses including: People with the surname *Barry Diller (born 1942), American businessman *Burgoyne Diller (1906–1965), American abstract painter * Dwight Diller (1946–2023), American musician * Karl Diller (born 1941), Germ ...

to redesign the park, including by adding a pedestrian walkway framing Lake Pitt, which is long. The museum is featured prominently in the 1992 cult classic film '' Encino Man'', where the title character recollects he was previously a caveman during his exploration of the museum's exhibits.

Heritage site

In respect of it being the "richest paleontological site on Earth for terrestrial fossils of late

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

age," the

International Union of Geological Sciences The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to global cooperation in the field of geology. As of 2023, it represents more than 1 million geoscientists around the world. About Fo ...

(IUGS) included the "Late Quaternary asphalt seeps and paleontological site of La Brea Tar Pits" in its assemblage of 100 geological heritage sites around the world in a listing published in October 2022. The organization defines an IUGS Geological Heritage Site as "a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history."

Flora and fauna

Among the prehistoric

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

species associated with the La Brea Tar Pits are Columbian mammoths, dire wolves, short-faced bears,

s (predominantly '' Paramylodon harlani'', with much rarer '' Megalonyx jeffersonii'' and '' Nothrotheriops shastensis)'' and the

state fossil Most states in the US have designated a state fossil, many during the 1980s. It is common to designate a fossilized species, rather than a single specimen or a category of fossils. State fossils are distinct from other state emblems like state d ...

of California, the saber-toothed cat (''

Smilodon ''Smilodon'' is an extinct genus of Felidae, felids. It is one of the best known saber-toothed predators and prehistoric mammals. Although commonly known as the saber-toothed tiger, it was not closely related to the tiger or other modern cats ...

fatalis''). Contrary to popular belief, the tar pits don't contain

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

remains, as these were

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

before the pits formed. The park is known for producing myriad mammal fossils dating from the

Wisconsin glaciation The Wisconsin glaciation, also called the Wisconsin glacial episode, was the most recent glacial period of the North American ice sheet complex, peaking more than 20,000 years ago. This advance included the Cordilleran Ice Sheet, which nucleated ...

. While mammal fossils generate significant interest, other fossils including fossilized insects and plants, and even pollen grains, are also valued. These fossils help define a picture of what is thought to have been a cooler, moister climate in the Los Angeles basin during the glacial age. Microfossils are retrieved from the matrix of asphalt and sandy clay by washing with a solvent to remove the petroleum, then picking through the remains under a high-powered lens. Historically, the majority of the mammals excavated from the La Brea deposits had been large carnivores, supporting a hypothesized "carnivore trap" in which large herbivores entrapped in asphalt attracted predators and scavengers which then became entrapped while trying to steal a quick meal. However, new research with an eye towards microfossils has revealed a stunning diversity and abundance of many types of mammals. According to paleontologist Thomas Halliday, "Rancho La Brea Tar Pits... where big herbivores typically get stuck in tar which naturally seeps from the ground, and as a result, you get huge concentrations of just specifically herbivores. You get a herbivorous sample of the ecosystem and very few carnivores, except those that are trying to scavenge on the already dead carcasses that have just got stuck in the tar."

Bacteria

Methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

gas escapes from the tar pits, causing bubbles that make the asphalt appear to boil. Asphalt and methane appear under surrounding buildings and require special operations for removal to prevent the weakening of building foundations. In 2007, researchers from UC Riverside discovered that the bubbles were caused by hardy forms of bacteria embedded in the natural asphalt. After consuming petroleum, the bacteria release methane. Around 200 to 300 species of bacteria were newly discovered here.Jia-Rui Chong
"Researchers learn why tar pits are bubbly"
''Los Angeles Times'', May 14, 2007.

Human presence

Only one human has been found, a partial skeleton of La Brea Woman (1914) Preliminary report on the discovery of human remains in an asphalt deposit at Rancho La Brea, ''Science'' 40: 197–203 dated to around 10,000

calendar year A calendar year begins on the New Year's Day of the given calendar system and ends on the day before the following New Year's Day, and thus consists of a whole number of days. The Gregorian calendar year, which is in use as civil calendar in ...

s (about 9,000 radiocarbon years) BP, (2009) Compilation, calibration, and synthesis of faunal and floral radiocarbon dates, Rancho La Brea, California, ''Contributions in Science'' 518: 1–16 who was 17 to 25 years old at death (1989) A note on the ontogenetic age of the Rancho La Brea hominid, Los Angeles, California, ''Bulletin, Southern California Academy of Sciences'' 88(3): 123–26 and found associated with remains of a domestic dog, so was interpreted to have been ceremonially interred. (1985) Domestic dog associated with human remains at Rancho La Brea, ''Bulletin, Southern California Academy of Sciences'' 84(2): 76–85 In 2016, however, the dog was determined to be much younger in date. Also, some even older fossils showed possible tool marks, indicating humans active in the area at the time. Bones of saber-toothed cats from La Brea showing signs of "artificial" cut marks at oblique angles to the long axis of each bone were radiocarbon dated to 15,200 ± 800 BP (uncalibrated). If these cuts are in fact tool marks resultant from butchering activities, then this material would provide the earliest solid evidence for human association with the Los Angeles Basin. Yet it is also possible that there was some residual contamination of the material as a result of saturation by asphaltum, influencing the radiocarbon dates.Technical report for power plant construction. CULTURAL RESOURCES.
California Energy Commission, Sacramento, California, December 2000

Gallery

File:Tar and flora.jpeg, Tar and wild flower run within La Brea campus (2014) File:Mammuthus columbi Page.jpg, Skeleton of a Columbian mammoth from the tar pits, displayed in the George C. Page Museum File:Smilodon and paramylodon at la brea.jpg, Models of a saber-toothed cat (''

fatalis'') and

on display in 2023 File:La Brea SW04.jpg, Fossil crate (2021) File:La Brea SW03.jpg, Lab technician working on recent specimen ZED (2021) File:La Brea SW02.jpg, Lab technician doing a 3-D scan of a fossil (2021)

References

External links

Page Museum – La Brea Tar Pits

* ttp://gocalifornia.about.com/od/calamenu/a/tarpits.htm Gocalifornia.com: La Brea Tar Pits – ''visitor guide''.
Palaeo.uk: "Setting the La Brea site in context."

NHM.org: Pit 91 excavations
{{Authority control Asphalt lakes Fossil parks in the United States Parks in Los Angeles Museums in Los Angeles Natural history museums in California Natural history of Los Angeles County, California Paleontology in California Pleistocene paleontological sites of North America California Historical Landmarks Landmarks in Los Angeles National Natural Landmarks in California Lagerstätten Petroleum in California Pleistocene California Articles containing video clips 1901 in paleontology 1964 in paleontology 20th century in Los Angeles Environment of Greater Los Angeles Mid-Wilshire, Los Angeles Wilshire Boulevard First 100 IUGS Geological Heritage Sites