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Powell Butte (other)
Powell Butte is an extinct cinder cone butte in Portland, Oregon, United States. It is part of the Boring Lava Field, which includes more than 80 small volcanic edifices and lava flows in the Portland–Vancouver metropolitan area. The region around Powell Butte has a cool climate, and the butte and its surroundings feature meadows, rivers, and mixed forests. Powell Butte hosts the Powell Butte Nature Park, which includes about of trails for biking, hiking, and horseback riding. Powell Butte lies within historic territory of the Confederated Tribes of the Grand Ronde Community of Oregon. The land surrounding the butte has been used for an orchard and dairy farming. Today two underground reservoirs at the Butte each hold of fresh water as a primary part of the public water system for Portland and much of the surrounding region. Geography and geology Powell Butte is located in Multnomah County in the U.S. state of Oregon. According to the U.S. National Geodetic S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multnomah County, Oregon
Multnomah County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the county's population was 815,428. Multnomah County is part of the Portland–Vancouver– Hillsboro, OR–WA Metropolitan Statistical Area. Though smallest in area, Multnomah County is the state's most populous county. Its county seat, Portland, is the state's largest city. History The area of the lower Willamette River has been inhabited for thousands of years, including by the Multnomah band of Chinookan peoples long before European contact, as evidenced by the nearby Cathlapotle village, just downstream. Multnomah County (the thirteenth in Oregon Territory) was created on December 22, 1854, formed out of two other Oregon counties – the eastern part of Washington County and the northern part of Clackamas County. Its creation was a result of a petition earlier that year by businessmen in Portland complaining of the inconvenient location of the Washington County seat in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confederated Tribes Of The Grand Ronde Community Of Oregon
The Confederated Tribes of the Grand Ronde Community of Oregon (CTGR) consists of twenty-seven Native American tribes with long historical ties to present-day western Oregon between the western boundary of the Oregon Coast and the eastern boundary of the Cascade Range, and the northern boundary of southwestern Washington and the southern boundary of northern California. The community has an Indian reservation, the Grand Ronde Indian Reservation, which was established in 1855 in Yamhill and Polk counties. Because the people had lived near each other, and often spoke more than one language for use in trading, after they were grouped together in the 19th century on the reservation, they refined a creole language that became known as Chinook Jargon. Although long forced to speak English, the people are working to conserve this native language named Chinuk Wawa. They have produced native speakers through immersion programs for young children. Members of the confederation The tribe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Tabor (Oregon)
Mount Tabor is an extinct volcanic vent with a city park on the volcano, located in Portland, Oregon's neighborhood of the same name. The name refers to Mount Tabor, Israel. It was named by Plympton Kelly, son of Oregon City pioneer resident Clinton Kelly. Cinder cone The peak of Mount Tabor is in elevation; about two-thirds of this is prominence since the surrounding land is about elevation. Near the peak, where a basketball court and outdoor amphitheater are now situated, part of the cinder cone has been cut away, and the rock is visible to park visitors. The remaining cinders were used to pave the nearby parking lot. The Tabor cinder cone is part of the Boring Lava Field, an extensive network of cinder cones and small shield volcanoes ranging from Boring, Oregon, to southwest Washington, and dating to the Plio-Pleistocene era. The lava field has been extinct for over 300,000 years. Three other cinder cones from this field also lie within the city of Portland ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelly Butte Natural Area
Kelly Butte Natural Area is a city park of about in southeast Portland in the U.S. state of Oregon, just east of Interstate 205. The park is named after pioneer Clinton Kelly, who settled the area east of the Willamette River in 1848. It is part of the Boring Lava Field, an extinct Plio-Pleistocene volcanic field that contains 32 cinder cones and shield volcanoes in or near Portland. The butte contains a now-sealed concrete bunker built as a civil defense emergency operations center in 1955–56 and later used for emergency dispatching. It appears in the film ''A Day Called X''. Human history In 1848, pioneer Clinton Kelly settled in the Willamette Valley in the area that is today southeast Portland. Present-day Clinton Street and Clinton Park bear his name. Clinton had five sons, one of whom, Plympton Kelly, established a farm on or near Kelly Butte. According to a 1906 obituary of Plympton Kelly, the farm was known as the Kelly Butte farm. In 1906, a prison and rock quar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larch Mountain (Multnomah County, Oregon)
Larch Mountain is an extinct volcano near Portland, Oregon, Portland, Oregon. The name is misleading, as no western larch (a large coniferous tree) can be found there. It received that name when early lumbermen sold the noble fir wood as larch. The peak can be reached between May and November on paved Larch Mountain Road, east of Corbett, Oregon, although the road is closed during the winter and spring months. The road leading to Larch Mountain from the Historic Columbia River Highway is 14 miles long, which closed at milepost 10 from Nov. through late May or early June due to snow. Geography Larch Mountain is located in Multnomah County, Oregon approximately east of Portland, Oregon, Portland, above the Columbia River Gorge. Although it has an elevation of , its prominence above the surrounding terrain is only . The summit of the mountain is accessible by Larch Mountain Road between May and November, which branches off from the Historic Columbia River Highway east of Corbett, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rift
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems. Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates. ''Failed rifts'' are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot. Two of these evolve to the poi ... [...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] |
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] |
Monogenetic Volcanic Field
A monogenetic volcanic field is a type of volcanic field consisting of a group of small monogenetic volcanoes, each of which erupts only once, as opposed to polygenetic volcanoes, which erupt repeatedly over a period of time. The small monogenetic volcanoes of these fields are the most common subaerial volcanic landform. Many monogenetic volcanoes are cinder cones, often with lava flows, such as Parícutin in the Michoacán-Guanajuato volcanic field, which erupted from 1943 to 1952. Some monogenetic volcanoes are small lava shields, such as Rangitoto Island in the Auckland volcanic field. Other monogenetic volcanoes are tuff rings or maars. A monogenetic field typically contains between ten and a hundred volcanoes. The Michoacán-Guanajuato field in Mexico contains more than a thousand volcanoes and is exceptionally large. Monogenetic fields occur only where the magma supply to the volcano is low or where vents are not close enough or large enough to develop plumbing systems f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cascades Volcano Observatory
The David A. Johnston Cascades Volcano Observatory (CVO) is a volcano observatory in the US that monitors volcanoes in the northern Cascade Range. It was established in the summer of 1980, after the eruption of Mount St. Helens.Google Books, ''Monitoring Volcanoes: Techniques and Strategies Used by the Staff of the Cascades Volcano Observatory, 1980-90'', Editors - John W. Ewert and Donald A. Swanson, Unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plio-Pleistocene
The Plio-Pleistocene is an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally defined Pliocene and Pleistocene epochs—marking from about 5 Mya to about 12 kya. Nominally, the Holocene epoch—the last 12 thousand years—would be excluded, but most Earth scientists would probably treat the current times as incorporated into the term "Plio-Pleistocene"; see below. In the contexts of archaeology, paleontology, and paleoanthropology, the Plio-Pleistocene is a very useful period to which scientists may assign the long and continuous run in East Africa of datable sedimentary layers and their contents (e.g. the Bouri Formation). These contents collectively present a focused view of the continuous evolution of the region's large vertebrates, especially the evolution of some African apes (hominids) to the earliest hominins; and then the development of the early humans and thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
