Overview: Sapphire lakes, pinnacle-studded ridges and flowered mountain slopes; this is the Mount Margaret Backcountry. Part of the Mount St. Helens National Volcanic Monument , this rugged and spectacular area offers hikers an opportunity to explore and discover the dramatic effects of the 1980 eruption of Mount St. Helens. The lateral blast, a hot stone-filled wind, shattered trees and swirled around peaks and basins as it toppled thousands of acres of pristine forest.