The prominent glaciers are those on Mount Olympus, covering approximately ten square miles. Beyond the Olympic complex are the glaciers of Mount Carrie, the Bailey Range, Mount Christie and Mount Anderson. In the company of these glaciers are perpetual snowbanks that have the superficial appearance of glacial ice. Because they are lacking in the criteria below, they are not true glaciers.
True glaciers are structurally three-layered bodies of frozen water.
Crevasses or deep cracks in the glaciers form as the ice is subjected to uneven flow over alpine terrain. Another structural feature is the bergschrund, which is a prominent crevasse like opening at the head of the glacier, where the ice has been pulled away from the mountain wall. There is no great advance of Olympic glaciers today, but there is not a rapid melting back of the ice either. Forward surges in glacial flow often occur after a number of very heavy winters and cool summers, but such activity has been relatively infrequent with Olympic glaciers in recorded time. The climate influencing Olympic glaciers is wet and temperate.