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In page Last Glacial Period:

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In the Sierra Nevada, three stages of glacial maxima, sometimes incorrectly called ice ages, were separated by warmer periods. These glacial maxima are called, from oldest to youngest, Tahoe, Tenaya, and Tioga.[1] The Tahoe reached its maximum extent perhaps about 70,000 years ago. Little is known about the Tenaya. The Tioga was the least severe and last of the Wisconsin episode. It began about 30,000 years ago, reached its greatest advance 21,000 years ago, and ended about 10,000 years ago.[citation needed]