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title: "La Brea Tar Pits — Ice Age Fossils in Downtown Los Angeles" description: "The La Brea Tar Pits in Los Angeles have yielded over 3.5 million fossils from the Pleistocene, including saber-toothed cats, dire wolves, and the only human remains found at the site." category: "Famous Sites" date: "2026-03-30"

The La Brea Tar Pits: A Window into Ice Age Los Angeles

The La Brea Tar Pits, located in the heart of urban Los Angeles, California, represent one of the world's most significant and accessible paleontological sites. For more than 50,000 years, natural asphalt has seeped to the surface, creating sticky pools that have entrapped and exquisitely preserved a vast and diverse assemblage of late Pleistocene life. These fossil deposits provide an unparalleled glimpse into the ecosystem of Southern California during the last Ice Age, revealing a lost world of mammoths, saber-toothed cats, and dire wolves. Today, the site is an active research hub and public museum, allowing visitors to witness paleontological discovery as it happens.

Location and Geology

The tar pits are situated in Hancock Park, along Wilshire Boulevard's "Miracle Mile," a name inspired by the area's rapid commercial development in the 20th century. The source of the asphalt (often colloquially called "tar," though it is more accurately asphalt or bitumen) is the Salt Lake Oil Field, a petroleum reservoir located deep beneath the city. This oil is a remnant of ancient marine plankton that were deposited in the Miocene ocean that once covered the Los Angeles Basin.

Over millennia, immense geological pressure has forced this crude oil upward through fissures and faults in the Earth's crust. As the oil reaches the surface, its lighter, more volatile components evaporate, leaving behind the thick, sticky asphalt. This process of seepage has been ongoing for tens of thousands of years and continues to this day. The seeps are not vast, open lakes of tar but rather a series of discrete, often deceptive pools. These can be shallow puddles or deep, viscous plugs, frequently obscured by water, dust, and leaves, making them a perfect natural trap.

Discovery and Early History

For centuries before European contact, the local Indigenous peoples, including the Tongva and Chumash, were well aware of the seeps. They used the asphalt as a versatile resource: a waterproof sealant for canoes and baskets, an adhesive, and for ceremonial purposes. The first written record of the pits comes from the Spanish Portolá expedition in 1769. Friar Juan Crespí noted the "springs of pitch" and their resemblance to those used for caulking ships in Spain.

For much of the 19th century, the area, then part of the Rancho La Brea land grant, was mined for its asphalt, which was used for roofing and paving in the growing settlements of Los Angeles and San Francisco. During these quarrying operations, workers frequently encountered large bones, which they often dismissed as the remains of local cattle or other modern animals that had become stuck. The true scientific importance of these fossils remained unrecognized until the turn of the 20th century.

A Century of Excavation

The scientific story of La Brea begins in 1901. Geologist William W. Orcutt, working for the Union Oil Company, was surveying the area when he recognized that the bones being unearthed were not from modern livestock but from extinct prehistoric animals. He collected a variety of fossils, including the skull of a saber-toothed cat, and brought them to the attention of paleontologists at the University of California, Berkeley.

This sparked a wave of scientific interest. From 1905 to 1913, paleontologists like John C. Merriam from UC Berkeley conducted the first systematic excavations. The sheer density of fossils was astonishing. However, the early methods were often crude, focused on recovering the large, spectacular megafauna skulls and skeletons.

In 1913, the owner of Rancho La Brea, George Allan Hancock, recognizing the site's immense value, granted the County of Los Angeles exclusive excavation rights for a period of two years. This led to a massive excavation effort, resulting in the recovery of hundreds of thousands of fossils. These collections formed the foundation of the new Los Angeles County Museum of History, Science, and Art (now the Natural History Museum of Los Angeles County). The most famous of these excavations is Pit 91, which was worked intensively from 1913 to 1915 and reopened for public viewing and excavation in 1969. It has since yielded over 600,000 specimens.

The Treasures of La Brea

The fossil assemblage from La Brea is one of the richest late Pleistocene deposits ever discovered, with over 3.5 million specimens cataloged to date, representing more than 600 species of animals and plants.

Mega-Predators: The most striking feature of the La Brea fauna is the incredible abundance of predators. The most famous is the saber-toothed cat, Smilodon fatalis. Over 2,000 individuals have been recovered, making it the California state fossil. These powerful cats, known for their 7-inch (18 cm) canine teeth, were ambush predators. Equally numerous is the dire wolf, Aenocyon dirus. With over 4,000 individuals found, it is the most common large mammal from the pits. Dire wolves were heavier and more robust than modern gray wolves, likely hunting in packs to take down large prey. Other predators include the American lion (Panthera atrox), short-faced bear (Arctodus simus), and coyotes.

Large Herbivores: These predators were drawn to the pits by a rich variety of herbivores that had become entrapped. Among the largest were Columbian mammoths (Mammuthus columbi) and the slightly smaller American mastodons (Mammut americanum). Enormous ground sloths, such as the Harlan's ground sloth (Paramylodon harlani), which was the size of an ox, are also common finds. Other herbivores include ancient bison (Bison antiquus), western horses (Equus occidentalis), and camels (Camelops hesternus).

Microfossils: Beyond the spectacular megafauna, the asphalt has also preserved a treasure trove of smaller remains. These "microfossils" include insects, plant seeds, pollen, shells, and the bones of small mammals, birds, reptiles, and amphibians. These tiny fossils are crucial for reconstructing the ancient environment in detail.

La Brea Woman: In 1914, excavators discovered the partial skeleton of a human, the only one ever found at the site. Known as "La Brea Woman," she was a young woman, estimated to be between 18 and 25 years old, who lived approximately 10,200 years ago. Isotopic analysis of her bones suggests a diet rich in terrestrial plants and game, not seafood. Her remains, found in association with a domestic dog, provide a rare and direct link to the first people who inhabited the Los Angeles Basin.

The Entrapment Process

The process of entrapment at La Brea was a slow, deceptive phenomenon. An animal, perhaps seeking water that had collected on the surface of a seep, would wander into the sticky asphalt. In the summer heat, the asphalt would be soft, and even a large animal could become mired. Its struggles would only serve to embed it further.

The cries of the distressed animal would then act as a "predator trap," attracting carnivores and scavengers like dire wolves and saber-toothed cats. In their eagerness for an easy meal, these predators would often become trapped themselves. This explains the unusual ratio of fossils found at La Brea: approximately nine predators for every one large herbivore, a dramatic inversion of what is seen in a typical, healthy ecosystem. This cycle would repeat over and over, with layers of animals and sediment accumulating over thousands of years.

The Page Museum and Ongoing Research

To house and display the immense collection of fossils, the George C. Page Museum was built directly on the site in Hancock Park and opened to the public in 1977. The museum is designed to showcase the fossils found just feet away, featuring dramatic skeletons of mammoths, mastodons, and saber-toothed cats. A key feature is the "Fish Bowl Lab," a glass-walled laboratory that allows the public to watch paleontologists and volunteers clean, repair, and identify fossils recovered from the pits.

Excavation is not just a thing of the past. In 2006, during the construction of an underground parking garage for the adjacent Los Angeles County Museum of Art (LACMA), a new, major fossil deposit was discovered. To save the find, 23 massive wooden boxes were built around sections of the deposit, which were then craned out of the ground and moved to the La Brea Tar Pits grounds. This salvage operation, dubbed "Project 23," has provided scientists with a wealth of new material. Among its most significant finds is a remarkably complete Columbian mammoth skeleton nicknamed "Zed." The ongoing work on Project 23 continues to yield new discoveries and insights into the Ice Age world.

Reconstructing an Ice Age Environment

The fossils from La Brea do more than just catalogue extinct animals; they allow scientists to reconstruct the entire paleoenvironment of Ice Age Los Angeles. Analysis of pollen, seeds, and wood fragments reveals a landscape that was cooler and moister than today's. It was likely a mosaic of coastal sage scrub, chaparral, and groves of redwood, pine, and oak trees, more akin to modern-day Monterey Bay than present-day L.A. The incredible diversity of life—from microscopic diatoms to mammoths—paints a picture of a thriving, complex ecosystem.

Visiting the La Brea Tar Pits

The La Brea Tar Pits and Museum are a unique destination where the public can experience paleontology in action. Visitors can walk through Hancock Park and see the active asphalt seeps, including the large Lake Pit with its life-sized mammoth models. Inside the museum, they can view the results of over a century of excavation. The ongoing work at the outdoor excavation pits, like Pit 91 and the Project 23 sites, allows visitors to see paleontologists unearthing fossils directly from the ground, making the Ice Age feel immediate and tangible. It remains a vital center for research, education, and public fascination with our planet's deep past.