Glaciers are formed when the annual snow accumulation exceeds the annual
snow reduction from melt-off, sublimation, etc. Over the
centuries, the weight of the snow compresses into blue ice. It is
so dense that all colors of light are absorbed by the glacier and only
the blue light can escape to be reflected back.
Mendenhall is part of the Juneau Icefield, which is a massive
accumulation of ice and snow covering over 1,500 square miles.
Scientists estimate the icefield's
snow and ice depth to be from 800 to over 4,500 feet. Juneau
Icefield is the fifth largest icefield in the Western Hemisphere,
spawning over 40 major and 100 minor glaciers. Mendenhall is the
most easily accessible - known as the "drive-up glacier".
Mendenhall Lake is about 200 feet
deep, and water temperatures in average 37 degrees Fahrenheit
year-round. Not a good place to swim at any time of the year!