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 als ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Lake County, Oregon
Lake County is one of the List of counties in Oregon, 36 counties in the U.S. state of Oregon. As of the 2020 United States census, 2020 census, the population was 8,160. Its county seat is Lakeview, Oregon, Lakeview. The county is named after the many lakes found within its boundaries, including Lake Abert, Summer Lake (Oregon), Summer Lake, Hart Lake (Oregon), Hart Lake, and Goose Lake (Oregon-California), Goose Lake. Lake County is in the High Desert (Oregon), 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, Oregon, Paisley to the south and the communities around Christmas Valley, Oregon, Christmas Valley, Fort Rock, Oregon, Fort Rock, and Silver Lake, Oregon, 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 ( ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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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]   |
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Hole-in-the-Ground
Hole-in-the-Ground is a large maar (volcanic explosion crater) in the Fort Rock–Christmas Lake Valley basin of Lake County, central Oregon, northeast of Crater Lake, near Oregon Route 31. It is about across, a little longer N-S than E-W. Its floor is about below the surrounding ground level and has a rim that rises above, the highest point on the east side. The crater formed during the late Pleistocene, between 13,500 and 18,000 years ago, at which time the Fort Rock basin was a lake and the location was near the shore. Basaltic magma intruding near the surface flashed ground water to steam, which blew out overlying rock and soil, along with some juvenile material. As material slid into the hole formed, it closed the vent and the process repeated, eventually forming the huge hole. Blocks as large as in size were flung as far as from the crater. To the west of Hole-in-the-Ground is an even bigger maar, , but older and more eroded, called Big Hole The Kimberley ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Artemisia Tridentata
'' Artemisia tridentata'', commonly called big sagebrush,MacKay, Pam (2013), ''Mojave Desert Wildflowers'', 2nd ed., , p. 264. Great Basin sagebrush or simply sagebrush (one of several related species of this name), is an aromatic shrub from the family Asteraceae. It grows in arid and semi-arid conditions, throughout a range of cold desert, steppe, and mountain habitats in the Intermountain West of North America. Big sagebrush and other ''Artemisia'' shrubs are the dominant plant species across large portions of the Great Basin. Sagebrush provides food and habitat for a variety of species, such as sage grouse, pronghorn antelope, grey vireo, pygmy rabbit, and mule deer. Several major threats exist to sagebrush ecosystems, including human settlements, conversion to agricultural land, invasive plant species, and wildfires. Native Americans have used the plant medicinally. It is also useful as firewood. Description Big sagebrush is a coarse, many-branched, pale-grey shru ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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University Of Oregon
The University of Oregon (UO, U of O or Oregon) is a Public university, public research university in Eugene, Oregon, United States. Founded in 1876, the university is organized into nine colleges and schools and offers 420 undergraduate and graduate degree programs. The university also operates the Ballmer Institute for Children's Behavioral Health in Portland, Oregon; the Oregon Institute of Marine Biology in Charleston, Oregon; and Pine Mountain Observatory in Central Oregon. UO's 295-acre campus is situated along the Willamette River. Most academic programs follow the 10-week quarter system. The university is Carnegie Classification of Institutions of Higher Education, classified among "R1: Doctoral Universities – Very high research activity" and is a member of the Association of American Universities. Since July 2014, UO has been governed by Board of Trustees of the University of Oregon, its own board of trustees. UO student-athletes compete as the Oregon Ducks and are pa ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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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]   |
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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 the 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 ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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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. No lower latitudes have 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 A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another ri ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Volcanic Ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during 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]   |
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Lapilli Tuff
Lapilli (: lapillus) 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'' 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 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 basal surge eruption. Most lapilli tuffs ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |