The Pleistocene Epoch (meaning "most recent") represents that time in our Earth's history from approximately 2 million years ago until about 10,000 year ago. During this time, glaciers advanced and receded four time across the northern quarter of the globe. At its maximum, the ice mass covered about three times its current extent, and reached heights of 13,000 feet (4,000 meters). With so much water trapped as ice, sea levels dropped to about 430 feet (130 m) below current levels.
The glacial advances may have been due to continental plate movements (which resulted in less-even water circulation in the oceans), to solar fluctuations, or to Milankovitch cycles (a combination of changes in the Earth's orbit and degree and direction of tilt of the Earth).
Classic Fossil-Bearing Sites
Rancho la Brea Tar Seeps
(California)
Solo River (Java)
Olduvai Gorge (Africa)
Three craterform structures of Pleistocene age have been discovered on Earth resulting from impacts with extraterrestrial bodies. An 11 km crater has been discovered in Ghana as a result of an impact about 1.3 million years ago; a 10 km crater in Kazakhstan was made about 750,000 years ago; and the famous Barringer Crater near Winslow, Arizona was formed about 50,000 years ago.
Rancho la Brea
The la Brea "Tar Pits" are not really pits at all. Rather, they are naturally occuring petroleum seeps near present-day Los Angeles, California. Animals would occasionally become trapped in the seep only to be discovered millenia later by roving fossil hunters. Larger animals found at la Brea include mammoths, sabertooth cats, giant ground sloths, dire wolves, and various birds.
Michigan Mastodons
Mastodons were large, elephant-like animals that roamed throughout various parts of North American during the Pleistocene. In Michigan, they are most commonly found in the southern half of the Lower Peninsula. A wide and extensive glacial river system may have prevented them from moving north. Mastodons were browsing animals, feeding on shoots and leaves. They thrived in the cool glacial climate.
The mastodon's fate may have been directly tied to the influx of humans into the region. Recent findings show that mastodons were actively hunted and their carcasses submerged for storage and preservation.
Pleistocene Graphics
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| Rancho La Brea |
Dire wolves |
Sabertooth and Sloth |
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| California Quail |
Brea Turkey and Magpie |
Sabertooth skeleton |
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| American Mastodon |
Mastodons |
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