La Brea Tar Pits in Los Angeles is an active paleontological site and museum built around natural asphalt seeps that have trapped and preserved plants and animals for tens of thousands of years. Formed when oil reached the surface and weathered into asphalt, the deposits created a predator trap that preserved not only famous Ice Age mammals such as saber-toothed cats, dire wolves, mammoths, and ground sloths, but also abundant smaller fossils that reveal a cooler, wetter ancient environment. Used long ago by Chumash and Tongva communities and recognized scientifically in 1901, the site became a major excavation center and remains globally important for late Quaternary fossils.

Photo: Wikipedia · Public domain

Photo: Wikipedia · Public domain

Photo: Wikipedia · Public domain

Photo: Wikipedia · Public domain