Northeast-looking photograph of a symmetrical, unnamed
U-shaped valley cut into the crystalline rocks of
the Coast Mountains, Tracy Arm, Tracy Arm-Ford's
Terror Wilderness, Tongass National Forest, Alaska.
The valley walls are >1,000 ft high and the valley
is ~1/3 mile wide. |
Hanging Valley
A former tributary glacier valley that is incised into the
upper part of a U-shaped glacier valley, higher than the floor
of the main valley. Hanging valley streams often enter the
main valley as waterfalls.
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North-looking oblique aerial photograph of a pair
of nested cirques and hanging valleys, located above
the surface of the thinning and retreating Bering
Glacier. A hanging glacier connects the upper valley
to the lower valley. A larger glacier flows out
of the lower valley, but glacier retreat during
the late 20th century has left its terminus hundreds
of feet above the main valley. Wrangell-Saint Elias
National Park, Chugach Mountains, Alaska. |
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Holocene
The current part of geologic time. The Holocene epoch began
~12,000 years ago, at the end of the Pleistocene epoch.
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Northeast-looking photograph showing a well-formed
sharp-peaked horn on the Juneau Icefield, Tongass
National Forest, Alaska. Bergschrunds delineate
the heads of the two glaciers located on the southeast
and southwest sides of the horn. Note the arete
ridge on the west side of the horn. |
Horn
A pointed, mountain peak, typically pyramidal in shape, bounded
by the walls of three or more cirques. Headward erosion has
cut prominent faces and ridges into the peak. When a peak
has four symmetrical faces, it is called a Matterhorn.
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North-looking oblique aerial photograph showing
an asymmetrical unnamed horn located in the Chugach
Mountains, near Cordova Peak, Chugach National Forest,
Alaska. Note the hanging glacier on its near side. |
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U.S. Department of the Interior |
U.S. Geological Survey