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Exploring the beautiful nature of California


California Nature: Glass Mountain Range


Glass Mountain is part of the rim of the Long Valley caldera, one of North America's largest volcanoes. It gets its name from the rhyolite and obsidian flows that compose it. These rocks are especially high in silica. Glass Mountain, on the Inyo National Forest, is one of the tallest peaks in Mono County, California. It consists of a sequence of lava domes, flows, and welded pyroclastic flows of rhyolite composition that were erupted between 2.1 and 0.8 million years ago. Obsidian, a naturally occurring volcanic glass, can be found on the mountain. The mountain is in the north end of Owens Valley, between the Sierra Nevada Range on the west and the White Mountains on the east. Glass Mountain Ridge Ride is a 11.2 mile out and back trail located near Bishop, California. The trail is primarily used for mountain biking and is accessible from March until November. At about 7500 feet you can feast your eyes on the natural beauty of the place. Watch for the shimmer of restless aspen leaves as the sun sifts through, tall Jeffrey pines hung with fat, handsome cones, wild roses straggling around the edges of the clearing as if to fence it in. A path leads back through dense woods to a little stream rippling over a mosaic of granite pebbles and black bits of obsidian. Clumps of golden birches crowd the stream, their yellow catkins drooping, pendant-like over the water. Wild iris bloom beside budding columbine.
Glass Mountain gets its name from the rhyolite and obsidian flows that compose it Climbing from this campsite to the 11,127-foot summit, 3500 feet of elevation is gained in about six miles. There is no official trail, but the impressions from numerous deer trails will mark a route. As you climb, you can rest beside the buttress and are soon high enough on the slope to look back over the canyon's mouth and see the road trailing out over the sage flat toward the Owens River. A continuous line of snowy Sierra peaks stand against the sky. On the opposite side of the canyon the slope, supporting a dense stand of pines, culminated in a rocky pinnacle. Bits of obsidian tinkle in the mixture of sand and pumice that slide underfoot. Bittelbrush, covered with yellow blooms, fill the air with the scent of honey, attracting bees, butterflies and hummingbirds. The leaves of the mountain mahogany bristle dark green against silver bark. A tiny rosy trumpet with yellow veins in its throat can often be found close to the ground, one of the less common species of mimulus. When one sees, side by side, the smooth, glossy black of obsidian and the grainy gray of granite, it is bard to believe that they are made up of essentially the same elements. Obsidian pushes up out of a volcano in a mass too viscous to crystallize and cools rapidly with a minimum of air holes. Granite also begins as hot magma but cools slowly, underground, and crystallizes.
Obsidian was a valuable raw material to the early Indians for arrow- heads, spear points, knives and bide scrapers. The Paiute Indians who used to inhabit Owens Valley in large numbers and whose descendants still live there, traded obsidian with coastal tribes for shells, and with inland tribes for hides. When an Indian found a new source of obsidian he didn't stake a personal claim to it. It belonged to the tribe as a whole. Obsidian quarries sometimes belonged to a number of tribes; even enemy tribes might meet there under truce, to gather materials for their weapons. Obsidian played such an important part in the lives of the Indians that in some tribes it came to have a religious significance. The craftsman who could turn out exceptionally fine implements found himself in a position to influence the minds of others. He would inspect each flake as it fell. His fellow tribesmen believed him if he declared that a certain flake had curative powers; they would keep that flake as a charm against disease. He might pronounce one flake poisonous and the next one non-poisonous even when they, came from the same piece. Many believed him without question when he said solemnly, "This point is for bear, this one for deer, this one for coyote and this for a human enemy."
glass mountain in Northern California Medicine Lake Volcano is a large shield volcano in northeastern California about 30 miles northeast of Mount Shasta. Medicine Lake Volcano has been erupting off and on for half a million years. The eruptions were gentle rather than explosive like Mount St. Helens, coating the volcano's sides with flow after flow of basaltic lava. Medicine Lake is part of the old caldera, a bowl-shaped depression in the mountain. It is believed that the Medicine Lake volcano is unique, having many small magma chambers rather than one large one. The most recent eruption occurred around 1,000 years ago when rhyolite and dacite erupted at Glass Mountain and associated vents near the caldera's eastern rim. No field evidence has been found to substantiate a report of an eruption in 1910. Glass Mountain consists of a spectacular, nearly treeless, steep-sided rhyolite and dacite obsidian flow that erupted just outside the eastern caldera rim and flowed down the steep eastern flank of Medicine Lake Volcano. Ten additional small domes of Glass Mountain rhyolite and rhyodacite lava lie to the north and one to the south. The age of Glass Mountain and its preceding pumice deposits has been a matter of discussion for some time. A radiocarbon dating age of 885+/-40 years before present was obtained on a dead incense-cedar tree without limbs or bark that is preserved in the edge of one of the distal tongues of the flow.
 
 
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