A glacier is an accumulation of ice large enough to move of its own
weight. Mountain glaciers form at high altitudes where snowfall exceeds
melting and the snow builds up annually until, largely due to its
weight, the lower layers become solid ice. When the depth of this ice
becomes great enough—100 feet or more—it will flow down slope and the
ice is transported to lower altitudes where warmer temperatures cause
the ice to melt. The glacier terminates where this melting equals the
amount of ice moving down from the area of accumulation.
[Illustration: LAKE ANGELES LIES IN A CIRQUE ON THE SIDE OF MOUNT
ANGELES.]
The glaciers in the Olympic Mountains today are small indeed compared to
the extensive glaciers that formerly filled the valleys and sculptured
the mountains. The shape of the land testifies that a greater number of
glaciers once were here. However, more than 60 glaciers, having a
collective area of at least 20 square miles, are present today in the
Olympic Mountains. Mount Olympus alone has 6 major glaciers, and the
total area of permanent snow and ice on it is more than 10 square miles.
Several other mountains also have glaciers, notably Mounts Anderson,
Christie, Tom, and Carrie.
In addition, there are numerous snow patches that remain from one winter
to the next but are not thick enough to form glaciers. Viewed from a
high position, a panorama of north-facing slopes presents a profusion of
snow and ice patches. The presence of so much snow and ice in mountains
of modest height does not mean they are enveloped with inhospitable
cold. It is due to the abundance of winter snow and considerable cool
weather which retards its melting.
Glaciers are very sensitive to climate. Even slight changes in snowfall
or temperature can cause them to advance or recede. Most glaciers
everywhere have been shrinking during the past century. In recent years,
western Washington climate has been cooler and wetter. As a result, many
glaciers in this region, including Blue Glacier, have enlarged slightly.
[Illustration: ANDERSON GLACIER NESTLES ON THE FLANK OF MOUNT
ANDERSON, ONE OF SEVERAL HIGH AND RUGGED PEAKS ON THE PARK’S EASTERN
EDGE.]