Glaciers

The Middle Teton Glacier can be viewed from the Lower Saddle trail. Old snow from the previous winter still remains along the top of the glacier when this photo was taken in mid-September. If the snow lasts through the summer into the next winter, it is called firn, if it remains for many years it will metamorphose into glacier ice.

KFinch/NPS Photo

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Snow blankets Grand Teton National Park in winter. As spring approaches that blanket shrinks; however, even in the heat of summer, snow and ice are present in the form of glaciers and snowfields. An average of 450 inches of snow falls in the Teton Range each year, feeding the glaciers and snowfields each winter, while the warm temperatures of the summer season eat away at this surplus of snow. Today, summer melt is outpacing winter snowfall and the glaciers are retreating.

Glaciers carry rocky debris from higher to lower elevations. This material can be carried on the surface, inside, or even frozen to the bottom of the glacier. All glaciers flow downhill due to gravity and are lubricated by the accumulation of meltwater under their base, a process called basal slippage.

One major feature you may see on a glacier is a crevasse. Crevasses are deep, V-shaped cracks found in the uppermost layer of the glacier. To visualize what happens to a glacier as it moves, imagine bending a Snickers bar into an arch, the surface of the bar will crack, while the base (nougat) remains flexible. This is how a glacier moves, the surface is rigid and cracks as the glacier moves over uneven terrain or around a corner, while the base is more plastic and will remain whole.

Glaciers have had a weighty impact on the area. Starting over two million years ago, ice flowed across this valley many times only to melt and begin again. At one point, ice over 3,000 feet thick flowed south from Yellowstone and across the valley floor burying the town of Jackson with 1,500 feet of ice. Today the mottled beauty of the mountains is punctuated by a contrast of dark and light. Exposed rock lies adjacent to snow or ice. Currently there are numerous snowfields and several named glaciers in the park that formed during a cool period called the Little Ice Age. These masses of moving ice have names like Schoolroom, Teton, Middle Teton, Triple, Falling Ice and Skillet glaciers.

For a good view of a glacier, drive four miles north from Moose along the inside park road to the Teton Glacier turnout. You will find an interpretive sign that will illustrate where the glacier can be found on the range.

To learn more about glaciers and geologic topics watch our video podcasts and geology animation video.