The conspicuous notch in the east rim of Mount St. Helens is the truncated
valley cut by the Shoestring Glacier. This glacier formerly was fed by an ice
and snow field at the summit of Mount St. Helens. The eruption of May 18, 1980,
decapitated the glacier and removed approximately three-quarters of its original
volume.
Excerpts from:
Doukas, 1990,
Road Guide to Volcanic Deposits of Mount St. Helens
and Vicinity, Washington: USGS Bulletin 1859, 53p.
Shoestring Glacier - May 18, 1980
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The May 18, 1980, pyroclastic flow scoured the surface of Shoestring Glacier and
incorporated its water, snow, and ice to form the lahars that swept down across
Muddy fan. Shoestring Glacier was beheaded, and most of the glacier's snow and
ice accumulation zone was removed when the upper parts of the mountain collapsed
during the early moments of the eruption.
Excerpt from:
Pringle, 1993, Roadside Geology of Mount St. Helens National Volcanic Monument
and Vicinity: Washington Department of Natural Resources, Division of Geology
and Earth Resources Information Circular 88.
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