These ‘Tar Pits’ in LA Aren’t Actually Tar, And Have Trapped Animals Since the Ice Age

La Brea Tar Pits, Los Angeles CA

Long before Hollywood, Los Angeles had its own star attractions: tar pits that caught and kept Ice Age animals.

These natural traps preserved over a million fossils, making La Brea one of the most important dig sites on Earth. Here’s the story behind these famous fossil beds and how to visit them.

Asphalt, Not Tar

The term “tar pits” is somewhat misleading, as the substance isn’t actually tar but asphalt, a naturally occurring petroleum product.

These seeps are mostly shallow, extending only a few inches deep. The oil rises from the Salt Lake Oil Field roughly 1,000 feet below.

As this oil reaches the surface, its lighter components evaporate, leaving behind thick, sticky asphalt that trapped countless animals. The tar pits formed during the Pleistocene Epoch (Ice Age), lasting from about 2.6 million to 11,700 years ago.

No dinosaur fossils exist here because during their era, this area was underwater.

Discovery and Documentation

Indigenous peoples like the Chumash and Tongva used the natural asphalt for waterproofing long before scientific study began.

The first written record came in 1769 when Franciscan friar Juan Crespi noted “springs of pitch” while traveling with the Portolá expedition.

For a century, people viewed the asphalt mainly as a resource until William Denton published the first scientific mention of extinct animal remains in 1875.

The turning point came in 1901 when geologist W.W. Orcutt recognized these fossils’ scientific value, with a coyote species later named after him (Canis latrans orcutti).

Hancock Park Establishment

The land containing the tar pits was originally part of Rancho La Brea, a Mexican Land Grant of over 4,400 acres given to Antonio Jose Rocha in 1828.

After California became part of the United States, George Allan Hancock eventually gained ownership.

He granted exclusive excavation rights to the Natural History Museum of Los Angeles County in 1913. This two-year arrangement proved incredibly productive, yielding 750,000 fossil specimens from 96 different sites.

Hancock’s commitment to preservation culminated in 1924 when he donated 23 acres to Los Angeles County with the condition that the park be preserved. This land became Hancock Park, which continues to protect the tar pits today.

The George C. Page Museum

For decades, fossils from La Brea were housed miles away at the Natural History Museum, frustrating philanthropist George C. Page.

He visited in 1917 hoping to see Ice Age skeletons. Later in life, Page funded the construction of an on-site museum. Work began in 1975, during which workers discovered an unusually rich fossil deposit containing the largest collection of connected specimens ever found at the site.

The George C. Page Museum opened in 1977, fulfilling Page’s vision of displaying fossils where they were found. Its distinctive circular design became iconic. In 2015, it was renamed the La Brea Tar Pits & Museum.

Today, you can still watch scientists at work through the glass-walled Fossil Lab.

Major Excavations

The scientific excavation of La Brea has an interesting evolution. Initially, ranch workers dismissed tar-covered bones as remains of domestic animals lost in the seeps.

Scientific excavation began in earnest in 1913, with workers digging 96 separate pits, though early methods were somewhat crude by today’s standards.

By the 1960s, techniques had greatly improved. In 1969, researchers launched the Rancho La Brea Project, reopening Pit 91 for its microfossils through stratigraphy.

The most recent major initiative, Project 23, began in 2006 when construction at the neighboring Los Angeles County Museum of Art uncovered 16 new fossil deposits. Scientists boxed these deposits and moved them to the Page Museum for careful excavation, work that continues today.

Notable Fossil Findings

La Brea’s fossil collection is remarkable in both quantity and diversity, with over one million bones recovered representing at least 231 vertebrate species.

The oldest material dates to approximately 38,000 years ago, though most fossils come from between 11,000 and 40,000 years ago.

Carnivores dominate the large mammal specimens, making up about 90% of the collection. The dire wolf (Aenocyon dirus) is most common, with roughly 4,000 individuals represented.

Among herbivores, the Ancient bison (Bison antiquus) appears most frequently, with at least 300 individuals identified, many being young animals.

This prevalence of predators supports the “carnivore trap” hypothesis: herbivores became stuck in asphalt, attracting predators that then also became trapped.

Saber-Toothed Cat (Smilodon fatalis)

No prehistoric creature symbolizes La Brea more than the saber-toothed cat, Smilodon fatalis, officially designated as California’s state fossil in 1974.

Its name perfectly captures this formidable hunter—Greek “smilodon” meaning “blade tooth” and Latin “fatalis” meaning “deadly”—referencing canines that reached up to 11 inches long.

One intriguing specimen shows evidence of hip dysplasia, yet survived to adulthood despite this handicap. This suggests Smilodon lived in social groups where members cared for injured individuals.

Scientific Importance

In 2022, the International Union of Geological Sciences designated La Brea as one of the first 100 IUGS Geological Heritage Sites, recognizing it as Earth’s richest Pleistocene fossil location.

Since 1951, La Brea has served as the “type locality” for the Rancholabrean North American Land Mammal Age, making it the reference site for fossils from 240,000-11,000 years ago across North America.

Visiting the La Brea Tar Pits & Museum

La Brea Tar Pits is the world’s only active Ice Age excavation site and located at 5801 Wilshire Blvd, Los Angeles.

The 23-acre Hancock Park features bubbling asphalt seeps and the iconic Lake Pit with life-sized models of trapped prehistoric animals.

You can also visit The Pleistocene Garden recreates native plants from 10,000-40,000 years ago, divided into four ecological zones based on 35 years of research.

Inside the museum, you can take the Excavator Tour exploring the transparent Fossil Lab, historic excavation sites, and Project 23 where active work continues.

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