Beneath Urban Los Angeles, Ancient Asphalt Still Traps Prehistoric Life in a Sticky Grave
In short: In the heart of Los Angeles, natural asphalt has seeped from the earth for tens of thousands of years. These sticky pools created a lethal predator trap, preserving everything from saber-toothed cats to pollen grains. Today, this site remains a rare, active window into the climate and creatures of the Pleistocene.
The La Brea Tar Pits are not true volcanic craters, but rather surface expressions of the Salt Lake Oil Field. Crude oil rises along the 6th Street Fault, losing its lighter components to evaporation and biodegradation until it becomes thick, viscous asphalt. This process has persisted for millennia, creating a unique environment that acts as a natural preservative for biological material. When animals became mired in the sticky pools, predators often followed, only to become trapped themselves—a phenomenon researchers call a predator trap.
While the site is famous for its dramatic megafauna, such as the Columbian mammoth, dire wolves, and the saber-toothed cat, the true scientific value lies in the sheer diversity of the remains. Excavations have yielded over one million specimens, including delicate microfossils like insects, seeds, and leaves. These remnants provide a detailed record of the Los Angeles basin during the Last Glacial Period, suggesting a regional environment that was significantly cooler and wetter than today. The asphalt effectively seals these bones, preventing bacterial degradation and leaving them remarkably intact.
The site’s history is as layered as its geology. Indigenous Chumash and Tongva people utilized the asphalt to waterproof their plank boats, and later, Spanish explorers documented the bubbling springs in 1769. Although early observers initially mistook the fossilized bones for modern livestock, the 20th century brought rigorous paleontological study. Today, ongoing work at sites like Pit 91 and Project 23 continues to reveal new findings, including evidence of human activity and the surprising role of bacteria in producing the methane gas that makes the asphalt appear to boil.
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Sources
- Summary by Intellect · source: La Brea Tar Pits
- Also: La Brea Tar Pits | California, Map, & Facts | Britannica
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