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Powderhorn Wilderness
The Powderhorn Wilderness is a wilderness area in Hinsdale and Gunnison counties, Colorado, United States, located northeast of Lake City. Description Most of the northern part of the wilderness area, , about 77.5%, is located on Bureau of Land Management land and its southern portion, , about 22.5%, is located within the Gunnison National Forest. Elevations in the wilderness range from at the West Fork Powderhorn Creek to at the summit of Calf Creek Plateau. The Powderhorn Wilderness is an important watershed for the Gunnison River. The area protects the East, Middle, and West forks of Powderhorn Creek, which flow into Cebolla Creek and then the Gunnison River. Calf Creek, which is on National Forest land, flows south and eventually joins Cebolla Creek. Within the wilderness area there are numerous small lakes and beaver ponds. The largest of these are Devil's Lake and Powderhorn Lake. Much of the area sits above timberline at and it is recognized as one of the lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hinsdale County, Colorado
Hinsdale County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 788, making it the second-least populous county in Colorado. With a population density of only , it is also the least-densely populated county in Colorado. The county seat and only incorporated municipality in the county is Lake City. The county is named for George A. Hinsdale, a prominent pioneer and former Lieut. Governor of Colorado Territory. Geography According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.5%) is water. Hinsdale County is one of the most remote counties in Colorado and the United States. The county is covered by mountains, including multiple fourteeners, and contains one of the largest roadless areas in the country. The continental divide crosses the county twice. Most of the county is divided among several different national forests and the Weminuche Wilderness area. Adjacent counties * Gunnison – nort ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Juan Volcanic Field
The San Juan volcanic field is part of the San Juan Mountains in southwestern Colorado. It consists mainly of volcanic rocks that form the largest remnant of a major composite volcanic field that covered most of the southern Rocky Mountains in the Middle Tertiary geologic time.Steven, Thomas A.; Lipman, Peter W. (1976)"Calderas of the San Juan Volcanic Field, Southwestern Colorado" ''U.S. Geological Survey Professional Papers''. Washington, DC: U.S. Government Printing Office. 958: 1–35. Retrieved 2012-05-16. There are approximately fifteen calderas known in the San Juan Volcanic Fields; however, it is possible that there are two or even three more in the region. The region began with many composite volcanoes that became active between 35 and 40 million years ago, with peak activity in the time period around 35-30 million years ago. Around this time the activity began to include explosive ash-flow eruptions. Many of these volcanoes experienced caldera collapse, resulting in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpine Tundra
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated alpine climate, harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, and alpine tundra merges with tundra#Arctic tundra, polar tundra. The high elevation causes an adverse climate, which is too cold and windy to support tree growth. Alpine tundra ecotone, transitions to sub-alpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone are known as ''Krummholz''. With increasing elevation it ends at the snow line where snow and ice persist through summer. Alpine tundra occurs in mountains worldwide. The flora of the alpine tundra is characterized by dwarf shrubs close to the ground. The cold climate of the alpine tundra is caused by adiabatic cooling of air, and is similar to polar climate. Geography Alpine tundra occurs at hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Powderhorn Wilderness (9470231399)
The Powderhorn Wilderness is a wilderness area in Hinsdale and Gunnison counties, Colorado, United States, located northeast of Lake City. Description Most of the northern part of the wilderness area, , about 77.5%, is located on Bureau of Land Management land and its southern portion, , about 22.5%, is located within the Gunnison National Forest. Elevations in the wilderness range from at the West Fork Powderhorn Creek to at the summit of Calf Creek Plateau. The Powderhorn Wilderness is an important watershed for the Gunnison River. The area protects the East, Middle, and West forks of Powderhorn Creek, which flow into Cebolla Creek and then the Gunnison River. Calf Creek, which is on National Forest land, flows south and eventually joins Cebolla Creek. Within the wilderness area there are numerous small lakes and beaver ponds. The largest of these are Devil's Lake and Powderhorn Lake. Much of the area sits above timberline at and it is recognized as one of the larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cirque
A (; from the Latin word ') is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic , meaning a pot or cauldron) and (; ). A cirque may also be a similarly shaped landform arising from fluvial erosion. The concave shape of a glacial cirque is open on the downhill side, while the cupped section is generally steep. Cliff-like slopes, down which ice and glaciated debris combine and converge, form the three or more higher sides. The floor of the cirque ends up bowl-shaped, as it is the complex convergence zone of combining ice flows from multiple directions and their accompanying rock burdens. Hence, it experiences somewhat greater erosion forces and is most often overdeepened below the level of the cirque's low-side outlet (stage) and its down-slope (backstage) valley. If the cirque is subject to seasonal melting, the floor of the cirque most often forms a tarn (small lake) behind a dam, which marks the down ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires distinguishing features, such as Crevasse, crevasses and Serac, seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand. Between lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breccia
Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia, and hydrothermal breccia. A megabreccia is a breccia composed of very large rock fragments, sometimes kilometers across, which can be formed by landslides, impact events, or caldera collapse. Types Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. These indicate that the gravel was deposited very close to its source area, since otherwise th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Garita Caldera
La Garita Caldera is a large caldera in the San Juan volcanic field in the San Juan Mountains near the town of Creede in southwestern Colorado, United States. It is west of La Garita, Colorado. The eruption that created the La Garita Caldera is among the largest known volcanic eruptions in Earth's history, as well as being one of the most powerful known supervolcanic events. Date The La Garita Caldera is one of a number of calderas that formed during a massive ignimbrite flare-up in Colorado, Utah and Nevada from 40–18 million years ago, and was the site of massive eruptions about , during the Oligocene Epoch. Area devastated The area devastated by the La Garita eruption is thought to have covered a significant portion of what is now Colorado. The deposit, known as the Fish Canyon Tuff, covered at least . Its average thickness is . The eruption might have formed a large-area ash-fall, but none has yet been identified. Size of eruption The scale of La Garita volcanism ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cochetopa Dome
Cochetopa Dome is a mountain in the San Juan Mountains, in Saguache County, Colorado. The mountain is located in the Gunnison National Forest. With a prominence of , Cochetopa Dome is the 110th most prominent summit in the state of Colorado. Geology Cochetopa Dome is a rhyolitic lava dome, extruded into the Cochetopa caldera approximately 27 million years ago. The Chochetopa caldera is one of over a dozen such collapsed volcanoes within the San Juan volcanic field. The caldera is approximately wide and vertical subsidence was up to . The Cochetopa caldera, with Cochetopa Dome within it, is one of the most recognizable of the calderas in the region. Helping preserve the structure of this particular caldera is that its development was more recent than many of the larger calderas elsewhere in the San Juan Mountains, thus there was less regional volcanism to disrupt the caldera's structure. Also, the caldera was only modestly filled with post-subsidence sediments and much of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek (''olígos'', "few") and (''kainós'', "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, ''tuffaceous sandstone''). Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called tufa in guidebooks and in television programmes. Volcanic ash The material that is expelled in a volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Canyon Tuff
The Fish Canyon Tuff is the large volcanic ash flow or ignimbrite deposit resulting from one of the largest known Explosive eruption, explosive eruptions on Earth, estimated at . (see List of largest volcanic eruptions). The Fish Canyon Tuff eruption was centred at the La Garita Caldera in southwest Colorado; the caldera itself would have formed by collapse, as a result of the eruption. Studies of the tuff show that it all belongs to one eruption due to its uniform bulk-chemical composition (SiO2=bulk 67.5–68.5% (dacite), matrix 75–76% (rhyolite) and consistent phenocryst content (35–50%) and mineralogical composition (plagioclase, sanidine, quartz, biotite, hornblende, sphene, apatite, zircon, Fe-Ti oxides are the primary phenocrysts). This tuff and eruption is part of the larger San Juan volcanic field and the Mid-Tertiary_ignimbrite_flare-up, Oligocene Southern Rocky Mountain ignimbrite flare-up. The Fish Canyon Tuff eruption occurred around 28 Million years ago. Sanidine c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
