|
This barrier-free trail leads to a view of the canyon cut by the upper Muddy
River. An andesite lava flow traveled through this canyon about 1,900 years
ago. the river has since cut into the weaker Tertiary volcanic deposits and
left the younger, more resistant lava flow as an erosional remnant. Some of the
outcrops of lava along the trail exhibit a platy jointing that is typical of
viscous andesite lava.
-- Exerpts 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
|
Mount St. Helens
Shoestring Glacier (north)
Link to: USFS Mount St. Helens National Volcanic Monument