The Pleistocene geologic time period lasted from 1.8 million years ago to 11,000 years ago. The fossils of La Brea have been used to characterized a broad range of fossil types, which are termed the Rancholabrean Mammalian Age. The fossils at La Brea are found within a sub-series of the Rancholabrean, called the Wisconsin, referring to the ice age events of that time.