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Scablands
The Channeled Scablands are a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods within the southeastern part of Washington state.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. The Channeled Scablands were scoured by more than 40 cataclysmic floods during the Last Glacial Maximum and innumerable older cataclysmic floods over the last two million years. These floods were periodically unleashed whenever a large glacial lake broke through its ice dam and swept across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. The last of the cataclysmic floods occurred between 18,200 and 14,000 years ago.Balbas, A.M., Barth, A.M., Clark, P.U., Clark, J., Caffee, M., O'Connor, J., Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J Harlen Bretz
J Harlen Bretz (2 September 1882 – 3 February 1981) was an American geologist, best known for his research that led to the acceptance of the Missoula Floods and for his work on caves. Early life and education Bretz was born on 2 September 1882, in the small town of Saranac in Ionia County, Michigan. He was the first of Oliver Joseph Bretz and Rhoda Maria Howlett's five children. His father was a farmer, and proud descendant of early German settler in Ohio, John Bretz. The county's birth registry recorded his name as "Harlan J Bretz" at birth, but he was listed as "Harland J Bretz" on the 1900 United States Census. When he entered college in 1901, he applied as "J Harlen Bretz". At around the time he completed his graduate studies in 1913, he stopped using a point after the initial at "J". According to his two children, his given name was actually "Harley". Bretz's daughter Rhoda Bretz Riley went on to explain that "he invented the Harlen thing, just as he had invented the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coulee
Coulee, or coulée ( or ), is any of various different landforms, all of which are kinds of valleys or drainage zones. The word ''coulee'' comes from the Canadian French ''coulée'', from French ''couler'' 'to flow'. The term is often used interchangeably in the Great Plains for any of a number of water features, from ponds to creeks. In southern Louisiana the word ''coulée'' (also spelled ''coolie'') originally meant a gully or ravine usually dry or intermittent but becoming sizable during rainy weather. As stream channels were dredged or canalized, the term was increasingly applied to perennial streams, generally smaller than bayous. The term is also used for small ditches or canals in the swamp. In the northwestern United States, coulee is defined as a large, steep-walled, trench-like trough, which also include spillways and flood channels incised into the basalt plateau. Types and examples * The dry, braided channels formed by glacial drainage of the Scabland ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Current Ripples
Giant current ripples (GCRs), also known as giant gravel bars or giant gravel dunes, are a form of subaqueous dune. They are active channel topographic forms up to 20 m high, which occur within near-thalweg areas of the main outflow routes created by Glacial lake outburst flood, glacial lake outburst floods. Giant current ripple marks are large scale analogues of small current ripples formed by sand in streams. Giant current ripple marks are important features associated with scablands. As a landscape component, they are found in several areas that were previously in the vicinity of large glacial lakes. Setting Giant current ripples are a geomorphological phenomenon associated with channeled scablands. Scablands form when proglacial lake, lakes dammed off by glaciers suddenly Glacial lake outburst flood, burst through their dams and empty their contents in giant flooding events. They are found in the Altai Mountains of Russia, as well as in the Columbia Plateau of the Geology of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Lake Missoula
Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about and contained about of water, half the volume of Lake Michigan. The ''Glacial Lake Missoula National Natural Landmark'' is located about 110 kilometers (68 mi) northwest of Missoula, Montana, at the north end of the Camas Prairie Valley, just east of Montana Highway 382 and Macfarlane Ranch. It was designated as a National Natural Landmark in 1966 because it contains the great ripples (often measuring high and long) that served as a strong supporting element for J Harlen Bretz's contention that Washington State's Channeled Scablands were formed by repeated cataclysmic floods over only about 2,000 years, rather than through the millions of years of erosion that had been previously assumed. The lake was the result of an ice dam on the Clark Fork caused by the southern encroachment of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Pardee
Joseph Thomas Pardee (May 30, 1871, in Salt Lake City, Utah; † March 2, 1960, in Philipsburg, Montana) was a U.S. geologist who worked for the U.S. Geological Survey, and contributed to the understanding of the origin of the Channeled Scablands. He discovered the trail of evidence left by Glacial Lake Missoula, a lake created by an ice dam wide and high during the most recent ice age. He discovered that when the dam broke, the water flowed towards the scablands, supporting J Harlen Bretz's theory of the cataclysmic floods. Biography Born in Salt Lake City, Joe grew up in a mining family. The family moved to Philipsburg, Montana, when Joe was three, and his father developed the Algonquin mine. Joe's education was at Presbyterian College in Deer Lodge, Montana, and the University of California at Berkeley. After college he opened an assay office and operated a gold and sapphire mine, but a growing interest in geology led him to the USGS. He was appointed to the Survey in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Missoula
Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about and contained about of water, half the volume of Lake Michigan. The ''Glacial Lake Missoula National Natural Landmark'' is located about 110 kilometers (68 mi) northwest of Missoula, Montana, at the north end of the Camas Prairie Valley, just east of Montana Highway 382 and Macfarlane Ranch. It was designated as a National Natural Landmark in 1966 because it contains the great ripples (often measuring high and long) that served as a strong supporting element for J Harlen Bretz's contention that Washington (state), Washington State's Channeled Scablands were formed by repeated cataclysmic floods over only about 2,000 years, rather than through the millions of years of erosion that had been previously assumed. The lake was the result of an proglacial lake, ice dam on the Clark Fork (rive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proglacial Lake
In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice. At the end of the last ice age about 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere. Moraine-dammed The receding glaciers of the tropical Andes have formed a number of proglacial lakes, especially in the Cordillera Blanca of Peru, where 70% of all tropical glaciers are. Several such lakes have formed rapidly during the 20th century. These lakes may burst, creating a hazard for zones below. Many natural dams (usually moraines) containing the lake water have been reinforced with safety dams. Some 34 such dams have been built in the Cordillera Blanca to contain proglacial lakes. Several proglacial lakes have also formed in recent decades at the end of glaciers on the eastern side ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outflow Channels
Outflow channels are extremely long, wide swathes of scoured ground on Mars.Carr, M.H. (2006), ''The Surface of Mars''. Cambridge Planetary Science Series, Cambridge University Press. They extend many hundreds of kilometers in length and are typically greater than one kilometer in width. They are thought to have been carved by huge outburst floods. Crater counts indicate that most of the channels were cut since the early Hesperian,Hartmann, W.K., and Neukum, G. (2001). "Cratering chronology and the evolution of Mars". In: ''Chronology and Evolution of Mars'', ed. R. Kallenbach et al. Dordrecht: Kluwer, p. 165-94. though the age of the features is variable between different regions of Mars. Some outflow channels in the Amazonis and Elysium Planitiae regions have yielded ages of only tens of millions of years, extremely young by the standards of Martian topographic features.Burr, D.M., McEwan, A.S., and Sakimoto, S.E. (2002). "Recent aqueous floods from the Cerberus Fossae", ''M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drumheller Channels National Natural Landmark
Drumheller Channels National Natural Landmark showcases the Drumheller Channels, which are the most significant example in the Columbia Plateau of basalt butte-and-basin Channeled Scablands. This National Natural Landmark is an extensively eroded landscape, located in south central Washington state characterized by hundreds of isolated, steep-sided hills (buttes) surrounded by a braided network of numerous channels, all but one of which are currently dry. It is a classic example of the tremendous erosive powers of extremely large floods such as those that reformed the Columbia Plateau volcanic terrain during the late Pleistocene glacial Missoula floods.J Harlen Bretz, (1923), The Channeled Scabland of the Columbia Plateau. ''Journal of Geology'', v.31, p.617-649 In 1986, the U.S. National Park Service recognized the significance and natural beauty of Drumheller Channels by designating them a National Natural Landmark. The geologist who initially recognized and documented the evi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniformitarianism
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe., "''The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference'' which, as Bacon showed nearly four hundred years ago, is ''the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown'' and, therefore, no way of reaching general conclusions from a finite number of observations." It refers to invariance in the metaphysical principles underpinning science, such as the constancy of cause and effect throughout space-time, but has also been used to describe spatiotemporal invariance of physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anastomosis
An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (such as the foramen ovale in a fetus' heart) or abnormal (such as the patent foramen ovale in an adult's heart); it may be acquired (such as an arteriovenous fistula) or innate (such as the arteriovenous shunt of a metarteriole); and it may be natural (such as the aforementioned examples) or artificial (such as a surgical anastomosis). The reestablishment of an anastomosis that had become blocked is called a reanastomosis. Anastomoses that are abnormal, whether congenital or acquired, are often called fistulas. The term is used in medicine, biology, mycology, geology, and geography. Etymology Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Greek ana- "up, on, upon", stoma "mouth" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outburst Flood
In geomorphology, an outburst flood—a type of megaflood—is a high-magnitude, low-frequency catastrophic flood involving the sudden release of a large quantity of water. During the last deglaciation, numerous glacial lake outburst floods were caused by the collapse of either ice sheets or glaciers that formed the dams of proglacial lakes. Examples of older outburst floods are known from the geological past of the Earth and inferred from geomorphological evidence on Mars. Landslides, lahars, and volcanic dams can also block rivers and create lakes, which trigger such floods when the rock or earthen barrier collapses or is eroded. Lakes also form behind glacial moraines or ice dams, which can collapse and create outburst floods. Definition and classification Megafloods are paleofloods (past floods) that involved rates of water flow larger than those in the historical record. They are studied through the sedimentary deposits and the erosional and constructional landforms th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
