Filters: Tags: Debris Avalanche (X)
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A database of geologic map of Three Sisters Volcanic Cluster as described in the original abstract: The geologic map represents part of a late Quaternary volcanic field within which scores of eruptions have taken place over the last 50,000 years, some as recently as ~1,500 years ago. No rocks of early Pleistocene (or greater) age crop out within the map area, although volcanic and derivative sedimentary rocks of Miocene and Pliocene age are widespread to the east and west and are certainly buried beneath the younger volcanic field. Of the 145 volcanic map units described herein, only 22 are certainly older than late Pleistocene (>126 ka), and 12 are postglacial (<15 ka). The oldest unit identified yields an age...
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Downloadable,
Map Service;
Tags: Andesite,
Basalt,
Basaltic andesite,
Bend, Oregon,
Dacite,
This is a database of the geologic map of the Lassen Peak, Chaos Crags, and Upper Hat Creek volcanic area as described in the original abstract: The Lassen Peak, Chaos Crags, and Upper Hat Creek map area lies near the southern end of the Cascade Range in northern California. The map area includes parts of the three elements that together form the Lassen volcanic center: the Lassen dacitic dome field, the Central Plateau andesitic lava field, and the underlying deeply eroded and partly altered Brokeoff andesitic stratocone. The Lassen volcanic center is the southernmost active long-lived center of the present-day Cascades volcanic arc. This geologic map contributes to understanding the youngest major volcanic events...
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Downloadable,
Map Service;
Tags: Andesite,
Basalt,
California,
Chaos Crags,
Dacite,
On May 18, 1980, Mount St. Helens, Washington, exploded in a spectacular and devastating eruption that resulted in previously unimaginable events that drastically altered the mountain and the surrounding area. One unprecedented event was the collapse of the summit and north flank of the volcano forming a huge landslide known as the ‘debris avalanche’ with a total volume of about 2.5 km3 (3.3 billion cubic yards). The debris avalanche swept around and up ridges to the north, but most of it turned westward as far as 23 km (14 mi) down the valley of the North Fork Toutle River and formed a hummocky deposit. This had a profound effect on the topography of the area, including transforming the summit cone of the volcano...
The Tyonek area in the northwestern Cook Inlet trough is rich in petroleum, coal, geothermal, aggregate, and timber resources, but the detailed geologic mapping necessary for planning future resource development exists only in part of the area. This report and geologic map provide basic surficial-geologic information useful for exploiting those resources and planning future utility corridor developments. In addition to mapping of surficial geologic units, we provide discussion of strategraphic evidence pertaining to physiographic relations and geologic history of volcaniclastic deposits derived from ancestral Mount Spurr, multiple phases of Quaternary glacial activity, Chakachatna River valley landslide complexes...
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