The dance starts with cracks opening deep beneath the mountain. Warm waters percolate upward, with small steam emissions. (March-April 1980.) The cracks open more, magma approaches the surface to culminate in the climactic eruption of May 18, 1980. Vancouver, Washington, 35 miles from Mount St. Helens, was the headquarters of the U.S. Geological Survey and Forest Service teams during the eruption. The VANCOUVER, USA INTERMEDIATE DANCE CLASS devised this dance commemorating the explosion, all the more appropriate since one of the class members, a geologist, worked on the volcano. Now, eight years after the eruption, the Mount St. Helens National Monument is open for all to view and climb the natural wonder of Washington.