The Wisconsin Glaciation, occurred in North America between 5,000-65,000 years before present.  The last major glacial event peaked about 16,000 years ago.  In eastern and central North America enormous continental glaciers scoured the landscape at this time.  In much of the west, alpine glaciers formed in the higher mountain ranges.
Alpine glaciers form when winter snowfall exceeds summer melt.  Over time snow accumulates and is compressed into ice.  Eventually gravity pulls the ice down mountain valleys and this mechanism continues so long as the snow supply exceeds snow melt.

Two factors are required for the formation of glaciers, cold temperatures and precipitation.  One factor is not necessarily more important than the other, but you have to have both to form ice.  For example, the southernmost glaciers in North America are found in the northern Sierra Nevada Mountains of California, not because it’s particularly cold there, but because it’s particularly wet.  In contrast, Alaska’s Brooks Range, the northernmost mountain range in the United States, has no glaciers at all, because it’s too dry.

In the Wasatch Mountains today snow does not accumulate from year to year.  Occasionally a small butterfly-shaped patch of snow will survive at the base of Devil’s Castle through the summer months.  Glaciers will only return to the Wasatch Mountains if there is a significant decrease in temperature (4-5 degrees Fahrenheit), a significant increase in precipitation (+30%) or a combination of both.

Alta’s remarkable topography and snow quality is the result of its complex geologic and glacial history.

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