What were the ice sheets and glaciers of the late Pleistocene Epoch?
During the Pleistocene Epoch (approximately 2 million to 10 thousand years ago), a continental glacier called the Cordilleran Ice Sheet built up, advanced and retreated several times in the mountains of western Canada. It spread out into the surrounding lowlands, including the Puget Sound region and parts of northern Washington, Idaho and Montana. The ice sheets advanced and then retreated several times, according to the sequence of sediments that the ice sheets left behind. However, the most completely understood ice sheet advance is the one that occurred most recently, near the end of the Pleistocene epoch. The most recent advance obscured much of the evidence of the earlier advances. Farther east, at about the same times as the Cordilleran Ice Sheet advanced, the separate Laurentide Ice Sheet spread from central Canada into other parts of the northern United States, from Maine and New York to as far west as central Montana. The Cordilleran Ice Sheet reached its last maximum advance,
