On what date did the 1980 eruption of Mount St. Helens, in which "Crater Glacier" was formed, occur?
Crater Glacier The Crater Glacier (also known as Tulutson Glacier) is a geologically young glacier that is located on Mount St. Helens, in the U.S. state of Washington. The glacier formed after the 1980 Eruption and due to its location, the body of ice grew rapidly, unknown to the public for nearly 20 years. The glacier once contained ice caves in the smooth ice before the 2004-2008 volcanic activity. The growth of the lava dome and volcanic eruptions from 2004 to 2008 significantly altered the appearance of the glacier. In the same time period, several agencies decided to put an official name on the glacier which, at first, was Tulutson Glacier. A later decision made Crater Glacier the official glacier name. Despite the volcanic activity, the glacier continued to advance and by mid-2008, the glacier completely encircled the lava domes. In addition, new glaciers (rock or ice) have formed around Crater Glacier as well.
Harrison Glacier Harrison Glacier is located in the US state of Montana in Glacier National Park. Situated on a southeast facing ridge immediately south of Mount Jackson, Harrison Glacier is the largest glacier in Glacier National Park and was estimated in 2005 to have an area of 466 acre . Though many experts have stated that all the glaciers in Glacier National Park may disappear by the year 2030, Harrison Glacier lost only 9 percent of its surface area in the 40-year period between 1966 and 2005 and will likely still exist well beyond 2030. Compared to many of the vanishing glaciers in Glacier National Park, Harrison Glacier has a much higher altitude accumulation zone (approximately 9000 ft ) which has allowed it to maintain some equilibrium in its glacier mass balance. Comparing images of the glacier taken in 1913 with those from 2009, indicates that the glacier has experienced thinning and retreat.