On what date did the 1980 eruption of Mount St. Helens, in which "Crater Glacier" was formed, occur?
1980 eruption of Mount St. Helens On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the state of Washington, United States. The eruption (a VEI 5 event) was the only significant volcanic eruption to occur in the contiguous 48 U.S. states since the 1915 eruption of Lassen Peak in California. However, it has often been declared as the most disastrous volcanic eruption in United States history. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a large bulge and a fracture system on the mountain's north slope.
Pelican Butte Pelican Butte is a steep-sided dormant shield volcano in the Cascade Range of southern Oregon. It is located 28 mi due south of Crater Lake and 12 mi northeast of Mount McLoughlin, and rises over 3800 ft directly above the shore of Upper Klamath Lake. Ice Age glaciers carved a large cirque into the northeast flank of the mountain, forming a steep bowl which is popular in winter with backcountry skiers and snowmobilers. Several proposals have been made over the last few decades for ski area development on the northeast flanks, but none of the proposals has obtained the regulatory approval from the United States Forest Service necessary to proceed with construction. If the ski area is ever built, its skiable vertical of over 3800 ft would be the largest in Oregon exceeding the 3590 ft of Timberline Lodge ski area on Mount Hood.