Mount St. Helens was formed by volcanic eruptions and flows over a long period of time. The Cascade Mountains were formed by the collision of the Juan de Fuca Plate with the North American plate. Lava was forced upward to create volcanoes s...
http://wiki.answers.com/Q/How_was_Mt_Saint_Helens_forme...
Mount St. Helens - Wikipedia, the free encyclopedia
Source
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 mile south of Seattle and 50 mile northeast of Portl...
en.wikipedia.org/wiki/Mount_St._Helens
1980 eruption of Mount St. Helens - Wikipedia, the free encyclopedia
Source
The 1980 eruption of Mount St. Helens , a stratovolcano located in Washington state, in the United States, was a major volcanic eruption. The eruption (which was a VEI = 5 event) was the only signif...
en.wikipedia.org/wiki/1980_eruption_of_Mount_St._Helens
The cataclysmic eruption of Mount St. Helens, Washington, on May 18, 1980, formed a deep north-facing horseshoe-shaped crater. Small eruptions from 1980 to 1986 built a lava dome. The lava dome can be seen here steaming within the crater.
pubs.usgs.gov/fs/2000/fs036-00/
A native Washingtonian's look at the reawakening of Mount St. Helens ... The snow on MSH that was not instantly flashed to steam by the heat, melted and formed large mudflows that destroyed 27 bridges, 200 homes, 185 miles of roadway, and 15 miles of railway.
www.olywa.net/radu/valerie/StHelens.html www.olywa.net/radu/valerie/StHelens.html
(1b) - The 7 Wonders of Mount St. Helens ... (1d) - Is the Lava Dome at Mount St. Helens Really 1 Million Years Old ... · Stratification formed by hurricane-velocity pyroclastic flows...
www.creationism.org/sthelens/ www.creationism.org/sthelens/
Mount St. Helens includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit; another formed Goat Rocks on the northern flank.
vulcan.wr.usgs.gov/Volcanoes/MSH/description_msh.html
Nearly horizontal, quasi-periodic erosional features of 7-m average transverse wavelength and of order 100-m length occur in scattered locations from 3.5 to 9 km from the crater at Mount St. Helens under deposits of the lateral blast of May 18, 1980. We attribute the erosional features to scouring by longitudinal...
www.agu.org/pubs/crossref/1988/JB093iB12p14793.shtml
This deposit is from the largest known lahar in the history of Mount St. Helens. This deposit is about 46 km (29 mi) downstream from the volcano in the Toutle River, but the lahar flowed all the way to the Pacific Ocean. It formed 2,500 years ago when either a large debris avalanche displaced water from Spirit Lake,
volcanoes.usgs.gov/Imgs/Jpg/MSH/30710609-001_caption.ht... volcanoes.usgs.gov/Imgs/Jpg/MSH/30710609-001_caption.html
Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome.
www.volcano.si.edu/world/volcano.cfm?vnum=1201-05-