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Challis Arc
The Challis Arc was an Eocene volcanic field that stretched from southwestern British Columbia through Washington to Idaho, United States. The volcanic field extended between 42 and 49 degrees north latitude and was about 1500 kilometers in length. It exhibited volcanic activity for about 10 million years.Moye, F. J., Hackett, W. R., Blakey, J. D., and Snider, L. G., 1988, "Regional geologic setting and volcanic stratigraphy of the Challis volcanic field, central Idaho", ''in'' Link, P. K., and Hackett, W. R., editors, Guidebook to the Geology of Central and Southern Idaho: Idaho Geological Survey Bulletin 27, p. 87–97. Remnants of the Challis Arc are found as granitic plutons in the North Cascades, the Okanagan Highlands and in southcentral Idaho. It was first theorized in 1979 that the volcanic field formed as a result of subduction of the eastern block of the Kula Plate between 57 and 37 million years ago. More recent publications argue that the Challis Arc was formed by more c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Cascades
The North Cascades are a section of the Cascade Range of western North America. They span the border between the Canadian province of British Columbia and the U.S. state of Washington and are officially named in the U.S. and Canada as the Cascade Mountains. The portion in Canada is known to Americans as the Canadian Cascades, a designation that also includes the mountains above the east bank of the Fraser Canyon as far north as the town of Lytton, at the confluence of the Thompson and Fraser Rivers. They are predominantly non-volcanic, but include the stratovolcanoes Mount Baker, Glacier Peak and Coquihalla Mountain, which are part of the Cascade Volcanic Arc. Geography The U.S. section of the North Cascades and the adjoining Skagit Range in British Columbia are most notable for their dramatic scenery and challenging mountaineering, both resulting from their steep, rugged topography. While most of the peaks are under in elevation, the low valleys provide great local relief, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kula Plate
The Kula Plate was an oceanic tectonic plate under the northern Pacific Ocean south of the Near Islands segment of the Aleutian Islands. It has been subducted under the North American Plate at the Aleutian Trench, being replaced by the Pacific Plate. The name ''Kula'' is from a Tlingit language word meaning "all gone". As the name suggests, the Kula Plate was entirely subducted around 48 Ma and today only a slab in the mantle under the Bering Sea remains. There is some evidence of a Resurrection Plate broken off from the Kula Plate and also subducted. Geological history The Kula Plate began subducting under the Pacific Northwest region of North America during the Late Cretaceous period much like the Pacific Plate does today, supporting a large volcanic arc system from northern Washington to southwestern Yukon called the Coast Range Arc. There was a triple junction of three ridges between the Kula Plate to the north, the Pacific Plate to the west and the Farallon Plate to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of British Columbia
The geology of British Columbia is a function of its location on the leading edge of the North American continent. The mountainous physiography and the diversity of rock types and ages hint at the complex geology, which is still undergoing revision despite a century of exploration and mapping. The country's most prominent geological features are mountain ranges, including the North American Cordillera, which stretches from Southern Mexico to Alaska. Terrane theory Terrane theory was first proposed by Jim Monger of the Geological Survey of Canada and Charlie Rouse in 1971 as an explanation for a set of fusulinid fossils found in central British Columbia. Rather than use facies changes or seaways (which were common explanations at the time), the two geologists proposed that the fossils in question had been part of an assemblage of rocks that had migrated across the Pacific Ocean to their present location. This theory was then developed by Porter Irwin and Davy Jones of the US ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Arcs
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Arc
A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc located further from the subducting plate than the trench. The oceanic plate is saturated with water, mostly in the form of hydrous minerals such as micas, amphiboles, and serpentine minerals. As the oceanic plate is subducted, it is subjected to increasing pressure and temperature with increasing depth. The heat and pressure break down the hydrous minerals in the plate, releasing water into the overlying mantle. Volatiles such as water drastically lower the melting point of the mantle, causing some of the mantle to melt and form magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone. Volcanic arcs are distinct from volcanic chains formed over hotspots in the middle of a te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Izanagi Plates. The Pacific Plate subsequently grew to where it underlies most of the Pacific Ocean basin. This reduced the Farallon Plate to a few remnants along the west coast of North America and the Phoenix Plate to a small remnant near the Drake Passage, and destroyed the Izanagi Plate by subduction under Asia. The Pacific Plate contains an interior hot spot forming the Hawaiian Islands. Boundaries The north-eastern side is a divergent boundary with the Explorer Plate, the Juan de Fuca Plate and the Gorda Plate forming respectively the Explorer Ridge, the Juan de Fuca Ridge and the Gorda Ridge. In the middle of the eastern side is a transform boundary with the North American Plate along the San Andreas Fault, and a boundary with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Plate
The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific Plate (which borders the plate to the west). It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust. The interior of the main continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of crustal material called terranes, which are accreted to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the Rocky Mountains is composed of such terranes. Boundaries The southern boundary with the Cocos Plate to the west and the Caribbean Plate to the east is a transform fault, represented by the Swan Islands Transform Fault unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Farallon Plate
The Farallon Plate was an ancient oceanic plate. It formed one of the three main plates of Panthalassa, alongside the Phoenix Plate and Izanagi Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west coast of the North American Plate—then located in modern Utah—as Pangaea broke apart and after the formation of the Pacific Plate at the centre of the triple junction during the Early Jurassic. It is named for the Farallon Islands, which are located just west of San Francisco, California. Over time, the central part of the Farallon Plate was completely subducted under the southwestern part of the North American Plate. The remains of the Farallon Plate are the Juan de Fuca, Explorer and Gorda Plates, subducting under the northern part of the North American Plate; the Cocos Plate subducting under Central America; and the Nazca Plate subducting under the South American Plate. The Farallon Plate is also responsible for transporting old i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonics
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid plates that constitute the Earth's outer shell interact with each other. Tectonics also provide a framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles is essential to geomorphologists to explain erosion patterns and other Earth surface features. Main types of tectonic regime Extensional tectonics Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere. This type of tectonics is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate 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 the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of the de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope Carbon-13, 13C in the atmosphere was exceptionally low in comparison with the more common isotope Carbon-12, 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Popigai impact structure, Siberia and in what is now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Okanagan Highland
The Okanagan Highland is an elevated hilly plateau area in British Columbia, Canada, and the U.S. state of Washington (where it is spelled Okanogan Highlands). Rounded mountains with elevations up to above sea level and deep, narrow valleys are characteristic of the region. Definition BC Geographical Names, a service of the British Columbia Integrated Land Management Bureau, defines the Okanagan Highland as an area extending southward from the Shuswap River and the Coldstream Valley, east of Vernon, British Columbia, for 85 miles to the 49th parallel and into the State of Washington, lying between the Monashee Mountains on the east, and the Thompson Plateau and the Okanagan Valley on the west. The eastern boundary of the Okanagan Highland is clearly defined by the valley of the Kettle River. The western boundary is drawn arbitrarily and is somewhat difficult to define, because there are no natural features to follow between Penticton in the Okanagan Valley and Lumby in the Col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
