During the pleistocene, pluvial lakes formed in the western United States as a result of extended periods of wet conditions.
The Pleistocene is commonly known as the Ice Age and constitutes the geological epoch which protacted from nearly 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene marks the culmination of the last glacial period as well as the end of the Paleolithic age used in archaeology.