Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, B. Bradley, University of Colorado. |
Earthquake-induced slide and alluvial fan on downstream side of Madison River, Montana. Light colored rock is dolomite marble, the more resistant rock that supported weathered, mica-rich, overlying layers. An earthquake in 1959 fractured this dolomite and caused a great avalanche of rock, dirt, and trees to cascade from the steep south wall of the Madison River Canyon, about 395 m above the canyon floor. The avalanche formed a barrier 60-120 m high that completely blocked the gorge and the flow of the Madison River and created a lake. Twenty-eight people were believed to have been engulfed in the 88,000 kg slide. Image Credit: B. Bradley. University of Colorado The slopes above streams and rivers are subjected to a variety of processes that cause them to recede and retreat from the river or stream channel. These processes, collectively called mass wasting, can be classified according to rapidity of movement and according to the type of materials that are transported. |
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