The Pleistocene, which generally corresponds to the Ice Age, is characterized by fluctuating climates that started around 3-2 million years ago and ended about 10,000 years ago, after a short, cold interval called the Younger Dryas. The Pleistocene is especially important in the application of ecological principles because it is associated with the evolution and extinction of a variety of mammals (Barnosky et al. 2004; Barnosky, 2005). In North America, the last part of the Pleistocene coincides with climate change, glacial advance and retreat, and the Rancholabrean land mammal age. The end of the Pleistocene also coincides with the earliest presence of humans in North America.
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