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Pilot Rock (Oregon)
Pilot Rock is a prominent volcanic plug located in the western Cascade Range near the east end of the Siskiyou Mountains, just east of the Siskiyou Summit near Ashland, Oregon. Rising thousands of feet above the Shasta and Rogue valleys, it is a landmark distinguishable from over away. At 25.6 million years old, it is one of the oldest formations of the Cascade Range. The rock is protected by the Cascade–Siskiyou National Monument and the Soda Mountain Wilderness. Several trails pass near Pilot Rock, including the Pacific Crest Trail. Geology Rising above the surrounding hills and thousands of feet above the Shasta and Rogue valleys, Pilot Rock is one of the most prominent features of the Cascade–Siskiyou National Monument. It was created when andesitic magma broke through a weak spot in the Earth's crust and solidified beneath the surface, forming a plug. The softer rock around the plug slowly eroded away, leaving Pilot Rock as it is seen today. Similar features include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bureau Of Land Management
The Bureau of Land Management (BLM) is an agency within the United States Department of the Interior responsible for administering federal lands. Headquartered in Washington DC, and with oversight over , it governs one eighth of the country's landmass. President Harry S. Truman created the BLM in 1946 by combining two existing agencies: the General Land Office and the Grazing Service. The agency manages the federal government's nearly of subsurface mineral estate located beneath federal, state and private lands severed from their surface rights by the Homestead Act of 1862. Most BLM public lands are located in these 12 western states: Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. The mission of the BLM is "to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations." Originally BLM holdings were described as "land nobody w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cascade–Siskiyou National Monument
The Cascade–Siskiyou National Monument is a United States national monument that protects of forest and grasslands at the junction of the Cascade Range and the Siskiyou Mountains in Southwestern Oregon and Northwestern California, United States. The monument is managed by the Bureau of Land Management as part of the National Landscape Conservation System. It was established in a presidential proclamation by President Bill Clinton on June 9, 2000 and expanded by President Barack Obama on January 12, 2017. History Native Americans are known from archaeological excavations to have inhabited the region for thousands of years. Nearly 100 dwelling and root-gathering sites belonging to the Modoc, Klamath, and Shasta tribes have been uncovered to date. By the 1880s, their lands were taken by white settlers, whose mining cabins still dot the region. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hornblende
Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks. The general formula is . Physical properties Hornblende has a hardness of 5–6, a specific gravity of 3.0 to 3.6, and is typically an opaque green, dark green, brown, or black color. It tends to form slender prismatic to bladed crystals, diamond-shaped in cross-section, or is present as irregular grains or fibrous masses. Its planes of cleavage intersect at 56° and 124° angles. Hornblende is most often confused with the pyroxene series and biotite mica, which are also dark minerals found in granite and charnockite. Pyroxenes differ in their cleavage planes, which intersect at 87° and 93°. Hornblende is an inosilicate (chain silicate) mineral, built around double chains of silica tetrahedra. These chains extend the length ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joint (geology)
A rock in Abisko fractured along existing joints possibly by mechanical frost weathering A joint is a break ( fracture) of natural origin in a layer or body of rock that lacks visible or measurable movement parallel to the surface (plane) of the fracture ("Mode 1" Fracture). Although joints can occur singly, they most frequently appear as joint sets and systems. A ''joint set'' is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A ''joint system'' consists of two or more intersecting joint sets. The distinction between joints and faults hinges on the terms ''visible'' or ''measurable,'' a difference that depends on the scale of observation. Faults differ from joints in that they exhibit visible or measurable lateral movement between the opposite surfaces of the fracture ("Mode 2" and "Mode 3" Fractures). Thus a joint may be created by either strict movement of a rock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timber Press
Workman Publishing Company, Inc., is an American publisher of trade books founded by Peter Workman. The company is comprised of either imprints: Workman, Workman Children’s, Workman Calendars, Artisan, Algonquin Books of Chapel Hill and Algonquin Young Readers, Storey Publishing, and Timber Press. From the beginning Workman focused on publishing adult and children’s non-fiction, and its titles and brands rank among the best-known in their fields, including: the WHAT TO EXPECT pregnancy and childcare guide; the educational series, ''Brain Quest'' and ''The Big Fat Notebooks;'' travel books like ''1,000 Places to See Before You Die'' and ''Atlas Obscura''; humor including ''The Complete Preppy Handbook'' and ''Bad Cat;'' award-winning cookbooks: ''The Noma Guide to Fermentation, The French Laundry Cookbook, Sheet Pan Suppers,'' ''The Silver Palate Cookbook, The Barbecue Bible;'' and novels including ''How the Garcia Girls Lost Their Accents'''', Water for Elephants'' and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Mountaineers Books
The Mountaineers is an alpine club in the US state of Washington. Founded in 1906, it is organized as an outdoor recreation, education, and conservation 501(c)(3) nonprofit organisation, and is based in Seattle, Washington. The club hosts a wide range of outdoor activities, primarily alpine mountain climbing and hikes. The club also hosts classes, training courses, and social events. The club runs a publishing business, Mountaineers Books, which has several imprints. Publications include '' Mountaineering: The Freedom of the Hills''. Organization and activities The Mountaineers has 7 branches in Western Washington, 3 mountain lodges, and 2 program centers, one in Magnuson Park in Seattle, and one in Tacoma. All classes and trips are organized. History Originally a Seattle-based part of the Mazamas, a Portland based group founded in 1894, The Mountaineers formed their own branch shortly after the 1906 Mazamas Mount Baker expedition and dubbed themselves "The Mountaine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argon–argon Dating
Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer method requires only one rock fragment or mineral grain and uses a single measurement of argon isotopes. 40Ar/39Ar dating relies on neutron irradiation from a nuclear reactor to convert a stable form of potassium (39K) into the radioactive 39Ar. As long as a standard of known age is co-irradiated with unknown samples, it is possible to use a single measurement of argon isotopes to calculate the 40K/40Ar* ratio, and thus to calculate the age of the unknown sample. 40Ar* refers to the radiogenic 40Ar, i.e. the 40Ar produced from radioactive decay of 40K. 40Ar* does not include atmospheric argon adsorbed to the surface or inherited through diffusion and its calculated value is derived from measuring the 36Ar (which is assumed to be of atmosph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shiprock
Shiprock ( nv, , "rock with wings" or "winged rock") is a monadnock rising nearly above the high-desert plain of the Navajo Nation in San Juan County, New Mexico, United States. Its peak elevation is above sea level. It is about southwest of the town of Shiprock, which is named for the peak. Governed by the Navajo Nation, the formation is in the Four Corners region and plays a significant role in Navajo religion, myth, and tradition. It is located in the center of the area occupied by the Ancient Pueblo People, a prehistoric Native American culture of the Southwest United States often referred to as the Anasazi. Shiprock is a point of interest for rock climbers and photographers and has been featured in several film productions and novels. It is the most prominent landmark in northwestern New Mexico. In 1975, Shiprock was designated as a National Natural Landmark by the National Park Service. Name The Navajo name for the peak, , "rock with wings" or "winged rock", refers t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devils Tower
Devils Tower (also known as Bear Lodge Butte) is a butte, possibly laccolithic, composed of igneous rock in the Bear Lodge Ranger District of the Black Hills, near Hulett and Sundance in Crook County, northeastern Wyoming, above the Belle Fourche River. It rises 1,267 feet (386 m) above the Belle Fourche River, standing 867 feet (265 m) from summit to base. The summit is 5,112 feet (1,559 m) above sea level. Devils Tower was the first United States national monument, established on September 24, 1906 by President Theodore Roosevelt. The monument's boundary encloses an area of . Name Native American names for the monolith include "Bear's House" or "Bear's Lodge" (or "Bear's Tipi", "Home of the Bear", "Bear's Lair"); Cheyenne, lkt, Matȟó Thípila, cro, Daxpitcheeaasáao ("Home of Bears"), "Aloft on a Rock" (Kiowa), "Tree Rock", "Great Gray Horn", and "Brown Buffalo Horn" ( lkt, Ptehé Ǧí). The name "Devil's Tower" originated in 1875 during an expedition led by Colonel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet, dwarf planet, or natural satellite. It is usually distinguished from the underlying mantle by its chemical makeup; however, in the case of icy satellites, it may be distinguished based on its phase (solid crust vs. liquid mantle). The crusts of Earth, Mercury, Venus, Mars, Io, the Moon and other planetary bodies formed via igneous processes and were later modified by erosion, impact cratering, volcanism, and sedimentation. Most terrestrial planets have fairly uniform crusts. Earth, however, has two distinct types: continental crust and oceanic crust. These two types have different chemical compositions and physical properties and were formed by different geological processes. Types of crust Planetary geologists divide crust into three categories based on how and when it formed. Primary crust / primordial crust This is a planet's "original" crust. It forms from solidification of a magma ocean. T ... [...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, su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
