Instead of water, some lakes are filled with the gooey petroleum substance known as asphalt, tar, or bitumen. It forms when crude oil thickens due to long contact with air. How thick is it? That varies, which is why animals can be trapped in it. At Pitch Lake in Trinidad, you can walk on the surface, but if you stand still, you’ll eventually begin to sink. That fate befell the ancient animals trapped in the La Brea tar pits in Los Angeles.
In addition to geologists and oil barons, asphalt lakes are objects of interest for naturalists and paleontologists too as well, because hidden beneath the sticky, gooey layers are remains of unimaginable amount of prehistoric life. Over thousands of years these lakes have swallowed saber-toothed cat, dire wolves, bison, horses, turtles, snails, clams, millipedes, gophers, mammoths and hundreds of other species of vertebrates and invertebrates. These animals had wandered too far looking for food perhaps, and became trapped in the asphalt. The trapped animals attracted predators who became stuck as well as. Death came either by suffocation or hunger. It’s a terrible way to die, but a fantastic way to preserve fossils.