Throughout much of the Pleistocene, much of northern North America was covered by two large ice sheets (See the small globe above to determine see these two ice sheets). The western ice sheet, called the Cordilleran, covered nearly all of Western Canada and southern Alaska.

The lower division of the time line, the Pleistocene, actually extends from 1.6 million to 10,000 years. It is a period of time during which several global ice ages occurred. You can see how Mount Rainier and its surroundings might have looked during the late Pleistocene by clicking on 15,000 or 20,000 years ago. The upper division, the Holocene, is period of a global warming, during which time the world's glaciers have retreated and sea level has risen. To see how Mt. Rainier's glaciers changed during the late Holocene, click on 1896, 1913,1974, or 1994. The red and blue bar next to the Holocene and Pleistocene bars show average global temperature during the past 20,000 years. The dark and medium blue bands show periods of global cooling. The red and pink bands show periods of global warming. Dark blue is coldest and bright red is warmest ^(c).