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Jemez Mountains
The Jemez Mountains (, Tewa: ''Tsąmpiye'ip'įn'', Navajo: ''Dził Łizhinii'') are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States. Numerous Puebloan Indian tribes have lived in the Jemez Mountains region for centuries before the Spanish arrived in New Mexico. The Pueblo Nations of this region are the Towa-speaking Jemez people, after whom the mountain range is named, and the Keres-speaking Zia People. Pueblos in the Jemez Mountains of New Mexico consisted of compact multistoried buildings which enclosed small plazas. Most of their several hundred rooms were probably occupied by single families, but some were storerooms. The Jemez Mountains include climates varying from desert at the lowest elevations to sub-arctic conditions at the highest elevations. A significant diversity of climate and vegetation is linked to gradients in elevation and the region's topographical features. The highest point in the range is Chicoma Moun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chicoma Mountain
Chicoma Mountain (; also spelled Tschicoma or Tchicoma) is the highest point in the Jemez Mountains, a prominent mountain range in the U.S. State of New Mexico. The tree line in this area is exceptionally high, and the mountain is forested almost all the way to its summit which is conspicuous from the towns of Los Alamos, New Mexico, Los Alamos, Santa Fe, New Mexico, Santa Fe, and Espanola, New Mexico, Española and other areas in the valley of the Rio Grande in northern New Mexico. Like the rest of the Jemez, it is of volcanic origin; it lies on the northeast rim of the Valles Caldera, one of the best examples of a caldera in the United States. The mountain is sacred to many of the Puebloan peoples of New Mexico, who traditionally regarded it as the "center of all." Much of it lies within the territory of the Santa Clara Pueblo. Access by hikers, hunters, and others, is correspondingly limited, although the summit can be reached via public lands on the north side. The Puye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pajarito Mountain Ski Area
Pajarito Mountain Ski Area (Pajarito) is located on the north face of Pajarito Mountain, one of the Jemez Mountains in north central New Mexico, west of Los Alamos. It is located on of privately owned land. Pajarito Mountain is owned and operated by volunteers and Mountain Capital Partners. A typical season runs from Christmas to early April, but an outstanding season may run from Thanksgiving to late April. Pajarito now has a snowmaking system and it is producing snow. Season passes are available with discounts available for early season purchase. In summer, Pajarito hosts numerous special events, many involving mountain biking. An extensive network of single and double track mountain bike trails criss-cross the mountain, including a new singletrack trail going to the summit. Pajarito hosts lift access downhill and freeride mountain biking off the Spruce chair, and has continued to do so after the Las Conchas Fire in 2011. There also are hiking trails, and horse riding is pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende. Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Geology of Mars, Martian crust. The name ''andesite'' is derived from the Andes mountain range, where this rock type is found in abundance. It was first applied by Christian Leopold von Buch in 1826. Description Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that is intermediate in its content of silica and low in alkali metals. It has less than 20% quartz and 10% feldspa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obsidian
Obsidian ( ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the margins of rhyolite, rhyolitic lava flows known as obsidian flows. These flows have a high content of silicon dioxide, silica, giving them a high viscosity. The high viscosity inhibits the atomic diffusion, diffusion of atoms through the lava, which inhibits the first step (nucleation) in the formation of mineral crystals. Together with rapid cooling, this results in a natural glass forming from the lava. Obsidian is hard, Brittleness, brittle, and amorphous; it therefore Fracture (mineralogy)#Conchoidal fracture, fractures with sharp edges. In the past, it was used to manufacture cutting and piercing tools, and it has been used experimentally as s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eruption
A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three main types of volcanic eruptions. Magmatic eruptions involve the decompression of gas within magma that propels it forward. Phreatic eruptions are driven by the superheating of steam due to the close proximity of magma. This type exhibits no magmatic release, instead causing the granulation of existing rock. Phreatomagmatic eruptions are driven by the direct interaction of magma and water, as opposed to phreatic eruptions, where no fresh magma reaches the surface. Within these broad eruptive types are several subtypes. The weakest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. Subduction is possible because the cold and rigid oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle. Once initiated, stable subduction is driven mostly by the negative buoyancy of the dense subducting lithosphere. The down-going slab sinks into the mantle largely under its own ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and volcanic gas, gas bubbles. Magma is produced by melting of the mantle (geology), mantle or the Crust (geology), crust in various tectonics, tectonic settings, which on Earth include subduction zones, continental rift (geology), rift zones, mid-ocean ridges and Hotspot (geology), hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal mush, crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by Fractional crystallization (geology), fractional crystallization, contaminati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jemez Lineament
The Jemez Lineament is a chain of late Cenozoic volcanic fields, long, reaching from the Springerville and White Mountains volcanic fields in East-Central Arizona to the Raton-Clayton volcanic field in Northeastern New Mexico. The lineament was long interpreted as a hotspot trace (Raton hotspot) due to its resemblance in length and direction to the Yellowstone hot spot trace, but there is no systematic progression in age along the trace and it is now interpreted as a hydrous subduction zone scar. This formed about 1.7 billion years ago, when oceanic crust was subducting under what was then the southern edge of North America. The arrival of a large island arc in the subduction zone shifted subduction further south, leaving remnants of oceanic crust at the top of the Earth's mantle along the former subduction zone. These are rich in hydrous minerals that lower the melting temperature of the rock containing them. This hydrous subduction scar now separates basement rock of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resurgent Caldera
In geology, a resurgent dome is a dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it. Unlike a lava dome, a resurgent dome is not formed by the extrusion of highly viscous lava onto the surface, but rather by the uplift and deformation of the surface itself by magma movement underground. Resurgent domes are typically found near the center of very large open calderas such as Yellowstone Caldera or Valles Caldera, and in turn such calderas are often referred to as "resurgent-type" calderas to distinguish them from the more common (but much smaller) calderas found on shield volcanoes and stratovolcanoes. The structure that makes a resurgent dome possible is a fracture zone made up of ring faults surrounded by concentric normal faults around the outside of the rings. During initial formation of the caldera these ring faults provide vents for ash-flow eruptions and are the point at which subsidence of the cauldron block occurs. Subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valles Caldera
The Valles Caldera (or Jemez Caldera) is a volcanic caldera in the Jemez Mountains of northern New Mexico. Hot springs, streams, fumaroles, natural gas seeps, and volcanic domes dot the caldera landscape. The highest point in the caldera is Redondo Peak, an resurgent lava dome located entirely within the caldera and surrounded by moat-like flows of rhyolitic solidified lavas. Located within the caldera are several grass valleys, or ''valles'', the largest of which is Valle Grande ( ), the only one accessible by a paved road. In 1975, Valles Caldera was designated as a National Natural Landmark by the National Park Service with much of the caldera being within the Valles Caldera National Preserve, a unit of the National Park System. The area has a varied history involving cultural significance, economic resources, scientific studies, and complex geological setting. History Use of Valles Caldera dates back to prehistoric times: spear points dating to 11,000 years ago have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanism
Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a heat source, usually internally generated, inside the body; the heat is generated by various processes, such as radioactive decay or tidal heating. This heat partially melts solid material in the body or turns material into gas. The mobilized material rises through the body's interior and may break through the solid surface. Causes For volcanism to occur, the temperature of the mantle must have risen to about half its melting point. At this point, the mantle's viscosity will have dropped to about 1021 Pascal-seconds. When large scale melting occurs, the viscosity rapidly falls to 103 Pascal-seconds or even less, increasing the heat transport rate a million-fold. The occurrence of volcanism is partially due to the fact that melted materi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
