Glaciers
An arctic realm of steeply sloped glacial ice, snow and rocks crown the peaks of the Olympic Mountains. While most are small, more than 60 active glaciers top the Olympic peaks. Appreciated by tourists and scientists alike, Mount Olympus is more than just the tallest mountain on the Olympic Peninsula. Standing almost 8,000 feet above sea level, the glacier atop Mount Olympus spans a monumental 10 square miles. Additional glaciers can be found atop Mount Carrie, the Bailey Range, Mount Christie and Mount Anderson.
Perpetual snowbanks are often mistaken for glacial ice. While they resemble glaciers, they lack the characteristics needed to be considered true glaciers. Structurally, true glaciers are always comprised of the same three layers of frozen water. Snow makes up the top layer. The middle layer is neve, which is a combination of snow and ice. A pliable layer of pure ice forms the bottom layer as a result of becoming compacted by the increasing weight of new upper layers. Another important difference between glaciers and perpetual snowbanks is that glaciers move while perpetual snowbanks are stationary.
The wet, temperate climate of the Olympic Peninsula greatly affects a glacier's motion. As snow at the foot of a glacier melts and snow and ice continue to accumulate at the glacier's head, the bottom layer of ice succumbs to the pull of gravity, allowing the glacier to begin moving down the mountain. Glacial movement is unique in that rocks are mixed into the glacier as it grinds downhill and erodes the landscape.
As long as winter snowfall exceeds summer snowmelt, the necessary conditions exist for glacial motion. This climactic influence is most clearly noted in the Mount Olympus complex of glaciers because this region experiences the greatest impact of Pacific storms. In fact, this region receives approximately 200 inches of precipitation (mostly in the form of snow) annually. The elevation and close proximity to the Pacific Ocean greatly influence the weather. As storm clouds and warm, moist air blow inland, they are trapped by the mountains. Cool air in the valleys rises, causing rain. By the time the storm passes over Mount Olympus, the clouds have lost most of their moisture and the rain ceases, leaving the east side of the mountain dry.
Striking geological features have been created in the Olympic Mountains by glacial ice movement. For example, thousands of years ago, when temperatures were much colder, the Olympic glaciers carved lake basins, U-shaped valleys and jagged peaks into the area's mountainous terrain. Erosion continues today, but on a smaller scale.
Glacial flow is variable, and the glaciers of the Olympic peninsula are considered slow moving when compared to Alaskan glaciers that are known, at times, to move several hundred feet per day.