Geologic Time

In order to be familiar with the last great Ice Age, one must understand the timeframe in which it occurred. With evidence suggesting that the Earth is 4.5 billion years old, geologists have divided the history of the Earth into units called eras. Within those eras are even smaller units of time called periods and epochs. The most recent era in the history of the Earth is the Cenozoic. Starting some 65 million years ago, the Cenozoic Era continues today. The Rancho La Brea fossil deposits began to form just 40,000 years ago, towards the end of the Pleistocene Epoch. These fossils are very recent compared to other pre-historic life forms. For instance, dinosaurs became extinct about 65 million years before the asphalt deposits or "tar pits" even began to form!

		Foot Note! If the Earth's history is represented on a 100 foot-long time line, the animals of Rancho La Brea would have lived within 1/100th of an inch (as thin a hair!) from the end of the time line.

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