ECOLOGY First Edition Chapter 20 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Five explosive eruptions of Mount St. Helens occurred during 1980, including this spectacular event of July 22. This eruption sent pumice and ash 6 to 11 miles into the air, and was visible in Seattle, Washington, 100 miles to the north. The view here is from the south. (July 22, 1980, by Michael P. Doukas, U.S. Forest Service) The slopes of Smith Creek valley, east of Mount St. Helens, show trees blown down by a lateral blast. Two U. S. Geological Survey scientists (lower right) give scale. The direction of the blast, shown here from left to right, is apparent in the alignment of the downed trees. Over four billion board feet of usable timber, enough to build 150,000 homes, was damaged or destroyed. (September 24, 1980, by Lyn Topinka, USGS/CVO) Blue Tunicates Cinder cones and Aa lava flow along South flank of Mauna Kea, Saddle Road, Big Island, Hawaii Daisy fleabane Horseweed Selective focus close-up of white aster flowers. Tasmanian Devil Sunflower in a field in August, Yamanashi Prefecture, Japan