A Tale of Two Slides (Told Tardily)

Rather than rushing to post WoGE #214 (look for it tomorrow), I want to take a couple of minutes to post a couple of landslide GigaPans that I had originally intended to post back in September to go with that month’s Landslide theme on Pathological Geomorphology.

The two slides that I want to highlight happened about 34 years apart and are located just outside the boundaries of two of America’s most visited national parks.

On or about June 23, 1925 about 38 million cubic meters of rocks and debris slid northward off of Sheep Mountain and into the valley of the Gros Ventre River, forming an impoundment that now holds back Lower Slide Lake. Almost two years later a portion of this landslide dam failed and the resulting flood wiped out the town of Kelly, Wyoming killing six people. In this GigaPan you can see the upper scar of the slide on Sheep Mountain and some of the debris that is still only sparsely vegetated over 80 years later.

On August 17, 1959 the M7.5 Hebgen Lake Earthquake triggered a massive landslide that blocked the drainage of the Madison River and formed the modern day Quake Lake. This 360 degree panorama is shot from atop the landslide deposit. To the south one can see the landslide scar on the facing ridge. All around the camera location are the blocks of bedrock displaced during the slide – some that ran up the hill opposite the landslide scar are the size of small houses.

Driving back towards Yellowstone, I paused for one last view back across Quake Lake…

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