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Fort Rock (Arizona)
Fort Rock is a tuff ring located on an ice age lake bed in north Lake County, Oregon, United States. The ring is about in diameter and stands about high above the surrounding plain. Its name is derived from the tall, straight sides that resemble the palisades of a fort. The region of Fort Rock–Christmas Lake Valley basin contains about 40 such tuff rings and maars and is located in the Brothers Fault Zone of central Oregon's Great Basin. William Sullivan, an early settler in the area, named Fort Rock in 1873 while searching for lost cattle. Geology Fort Rock was created when basalt magma rose to the surface and encountered the wet muds of a lake bottom. Powered by a jet of steam, molten basalt was blown into the air, creating a fountain of hot lava particles and frothy ash. The pieces and blobs of hot lava and ash rained down around the vent and formed a saucer-shaped ring of lapilli tuff and volcanic ash sitting like an island in the lake waters. Steam explosions also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake County, Oregon
Lake County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 8,160. Its county seat is Lakeview. The county is named after the many lakes found within its boundaries, including Lake Abert, Summer Lake, Hart Lake, and Goose Lake. Lake County is in the high desert region known as the Oregon Outback, on the northwestern edge of the Great Basin. The county is generally divided between the communities around Lakeview and Paisley to the south and the communities around Christmas Valley, Fort Rock, and Silver Lake to the north. Its economy consists largely of agriculture and natural resource management and extraction. It is home to many large cattle ranches, hay farms, and timber holdings (both public and private), as well as several frontier towns and early 20th-century homesteads. Although lumber was once a primary economic driver in Lake County, today only one mill remains, at Lakeview. History Pre-Columbian Pre-Clovis era c ... [...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 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 gas bubbles. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artemisia Tridentata
''Artemisia tridentata'', commonly called big sagebrush,MacKay, Pam (2013), ''Mojave Desert Wildflowers'', 2nd ed., , p. 264. Great Basin sagebrush or (locally) simply sagebrush, is an aromatic shrub from the family Asteraceae, which grows in arid and semi-arid conditions, throughout a range of cold desert, steppe, and mountain habitats in the Intermountain West of North America. The vernacular name "sagebrush" is also used for several related members of the genus ''Artemisia'', such as California sagebrush (''Artemisia californica''). Big sagebrush and other ''Artemisia'' shrubs are the dominant plant species across large portions of the Great Basin. The range extends northward through British Columbia's southern interior, south into Baja California, and east into the western Great Plains of New Mexico, Colorado, Nebraska, and the Dakotas. Several major threats exist to sagebrush ecosystems, including human settlements, conversion to agricultural land, livestock grazing, inva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Oregon
The University of Oregon (UO, U of O or Oregon) is a public research university in Eugene, Oregon. Founded in 1876, the institution is well known for its strong ties to the sports apparel and marketing firm Nike, Inc, and its co-founder, billionaire Phil Knight. UO is also known for serving as the filming location for the 1978 cult classic ''National Lampoon's Animal House''. UO's 295-acre campus is situated along the Willamette River. The school also has a satellite campus in Portland; a marine station, called the Oregon Institute of Marine Biology, in Charleston; and an observatory, called Pine Mountain Observatory, in Central Oregon. UO's colors are green and yellow. The University of Oregon is organized into nine colleges and schools: the College of Arts and Sciences, Charles H. Lundquist College of Business, College of Design, College of Education, Robert D. Clark Honors College, School of Journalism and Communication; School of Law; School of Music and Dance; and the Gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luther Cressman
Luther Sheeleigh Cressman (October 24, 1897 – April 4, 1994) was an American field archaeologist, most widely known for his discoveries at Paleo-Indian sites such as Fort Rock Cave and Paisley Caves, sites related to the early settlement of the Americas. Early years Cressman was born outside of Pottstown, Pennsylvania, the son of a physician. He was ordained an Episcopal priest in 1923. Majoring in Classics, he graduated with a B.A. degree from Pennsylvania State University in 1918. Feeling doubts about his vocation, he began studying sociology and anthropology at Columbia University in New York. He received his Ph.D. from Columbia in 1928, and that same year, he left the priesthood. Career In 1929, he took a position as Professor of Sociology at the University of Oregon. The Department of Anthropology was founded by him six years later. His first hire for the department was Homer Barnett. Cressman was the chair of the department from 1935 until his retirement in 1963. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fort Rock Cave
Fort Rock Cave was the site of the earliest evidence of human habitation in the US state of Oregon before the excavation of Paisley Caves. Fort Rock Cave featured numerous well-preserved sagebrush sandals, ranging from 9,000 to 13,000 years old. The cave is located approximately west of Fort Rock near Fort Rock State Natural Area in Lake County. Fort Rock Cave was declared a National Historic Landmark in 1961, and added to the National Register of Historic Places in 1966.. The cave was found on Reub Long's ranch. It was formerly known as Menkenmaier Cave and Cow Cave. Description Fort Rock Cave sits in the Fort Rock formation, and shares geological similarities to its surroundings, with presence of Hayes Butte basalt, and exposed Pliocene-era lava. Additionally, there is pumice and ash from Mount Mazama (deposited by the explosion forming Crater Lake about 7600 years ago). The opening of the cave is approximately 70 feet across, with a depth of near 60 feet, making it the lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluvial
In geology and climatology, a pluvial is either a modern climate characterized by relatively high precipitation or an interval of time of variable length, decades to thousands of years, during which a climate is characterized by relatively high precipitation or humidity, Subdivisions of a pluvial, which are characterized by relatively high precipitation, are known as a subpluvials. Formally, pluvials were equated with glacial stages of the Quaternary. However, pluvials, as in equatorial regions, can also occur during interglacial stages. Lower latitudes have even experienced major pluvials in early to mid-Holocene times. In geomorphology, a pluvial refers to a geologic episode, change, process, deposit, or feature that is the result of the action or effects of rain. Sometimes, it also refers to the fluvial action of rainwater flowing in a stream channel, including a flood, known as a pluvial flood, that is the direct result of excessive precipitation.Bradley, R.S. (2015) ''Paleoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as ''tephra''), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away. Due to its wide dispersal, ash can have a number of impacts on society, including animal a ... [...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] |
Lapilli
Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range from in diameter. A pyroclastic particle greater than 64 mm in diameter is known as a volcanic bomb when molten, or a volcanic block when solid. Pyroclastic material with particles less than 2 mm in diameter is referred to as volcanic ash. Formation Lapilli are spheroid-, teardrop-, dumbbell- or button-shaped droplets of molten or semi-molten lava ejected from a volcanic eruption that fall to earth while still at least partially molten. These granules are not accretionary, but instead the direct result of liquid rock cooling as it travels through the air. Lapilli tuffs are a very common form of volcanic rock typical of rhyolite, andesite and dacite pyroclastic eruptions, where thick layers of lapilli can be deposited during a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
