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Kolk (vortex)
A kolk is an underwater vortex causing hydrodynamic scour by rapidly rushing water past an underwater obstacle. High-velocity gradients produce a high-shear rotating column of water, similar to a tornado. Kolks can pluck multiple-ton blocks of rock and transport them in suspension for kilometres. Kolks leave clear evidence in the form of kolk lakes, a kind of plucked-bedrock pits or rock-cut basin. Kolks also leave downstream deposits of gravel-supported blocks that show percussion but no rounding. Examples Kolks were first identified by the Dutch, who observed kolks hoisting several-ton blocks of riprap from dikes and transporting them away, suspended above the bottom. The Larrelt kolk near Emden appeared during the 1717 Christmas flood which broke through a long section of the dyke. The newly formed body of water measured roughly 500 × 100 m and was 25 m deep. In spite of the repair to the dyke, another breach occurred in 1721, which produced more kolks be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kolk Plucked Pothole
Kolk may refer to: People * Douglas Kolk (1963–2014), American artist * Hanco Kolk (born 1957), Dutch cartoonist * Lembit Kolk (politician), Lembit Kolk (1907–2003), Estonian politician * Raimond Kolk (1924–1992), Estonian writer and critic * Santi Kolk (born 1981), Dutch footballer * Scott Kolk (1905–1993), American actor * Oets Kolk Bouwsma (1898–1978), American philosopher Other * KOLK, a radio station licensed to Lakeside, Montana, United States * Kolk (bog), a waterbody in the middle of a raised or kettle bog * Kolk (vortex), a powerful underwater vortex * Kolk, Zagorje ob Savi, a settlement in Upper Carniola, Slovenia * Kolk (Heidmark), a village destroyed to make the Bergen-Hohne Training Area in Lower Saxony, Germany * Kolk-Spandau, a subdivision of Spandau (locality), Spandau in Spandau Borough, Berlin, Germany See also * Van der Kolk, a surname (including a list of people with the name) {{disambiguation, geo, surname, callsign Dutch-language surnames Esto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sprague Lake (eastern Washington)
Sprague Lake is a lake in Washington, straddling the border of Adams and Lincoln counties. It is two miles west of the town of Sprague. Sprague Lake is drained by Cow Creek, a tributary of the Palouse River. The lake was originally called Lake Colville. Sprague Lake is used for sport fishing of rainbow and cutthroat trout, largemouth bass, bluegill, as well as brown bullhead, channel catfish, black crappie, and yellow perch The yellow perch (''Perca flavescens''), commonly referred to as perch, striped perch, American perch or preacher is a freshwater perciform fish native to much of North America. The yellow perch was described in 1814 by Samuel Latham Mitchill fr .... See also * List of lakes in Washington References Bodies of water of Adams County, Washington Bodies of water of Lincoln County, Washington Lakes of Washington (state) {{AdamsCountyWA-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomorphology
Geomorphology () is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology, and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field. Overview Earth's surface is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence, and shape the coastal geography. Surface processes comprise the action of water, wind, ice, wildfire, and lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanography
Oceanography (), also known as oceanology, sea science, ocean science, and marine science, is the scientific study of the ocean, including its physics, chemistry, biology, and geology. It is an Earth science, which covers a wide range of topics, including ocean currents, waves, and geophysical fluid dynamics; fluxes of various chemical substances and physical properties within the ocean and across its boundaries; ecosystem dynamics; and plate tectonics and seabed geology. Oceanographers draw upon a wide range of disciplines to deepen their understanding of the world’s oceans, incorporating insights from astronomy, biology, chemistry, geography, geology, hydrology, meteorology and physics. History Early history Humans first acquired knowledge of the waves and currents of the seas and oceans in pre-historic times. Observations on tides were recorded by Aristotle and Strabo in 384–322 BC. Early exploration of the oceans was primarily for cartography and mainly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrodynamic Scour
lang=en, upright=1.3, Mechanism of formation, alt=sketch Hydrodynamic scour is the removal of sediment such as silt, sand and gravel from around the base of obstructions to the flow in the sea, rivers and canals. Scour, caused by fast flowing water, can carve out scour holes, compromising the integrity of a structure. It is an interaction between the hydrodynamics and the geotechnical properties of the substrate. It is a notable cause of bridge failure and a problem with most marine structures supported by the seabed in areas of significant tidal and ocean current. It can also affect biological ecosystems and heritage assets. Mechanism Any obstruction within flowing water will produce changes in velocity within the water column. The flow changes that occur in the vicinity of the substrate may cause differential movement in the bed materials near the obstruction. The magnitude of these changes varies with stream velocity, feature shape and substrate character. Generally the str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tualatin River
The Tualatin River is a tributary of the Willamette River in Oregon in the United States. The river is about long, and it drains a fertile farming region called the Tualatin Valley southwest and west of Portland at the northwest corner of the Willamette Valley. There are approximately 500,000 people residing on 15 percent of the land in the river's watershed. Course The Tualatin River arises near Windy Point on the eastern side of the Northern Oregon Coast Range. It begins in the Tillamook State Forest in Washington County and flows about to the Willamette River near West Linn in Clackamas County. The maps, which include river mile (RM) markers from the mouth to RM 76.7 or river kilometer (RK) 123.4, cover the following quadrants from mouth to source: Canby, Lake Oswego, Beaverton, Scholls, Hillsboro, Laurelwood, Forest Grove, Gaston, Turner Creek, and Gobblers Knob. Along the way, it falls from about above sea level to about , most of that occurring in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland, Oregon
Portland ( ) is the List of cities in Oregon, most populous city in the U.S. state of Oregon, located in the Pacific Northwest region. Situated close to northwest Oregon at the confluence of the Willamette River, Willamette and Columbia River, Columbia rivers, it is the county seat of Multnomah County, Oregon, Multnomah County, Oregon's most populous county. Portland's population was 652,503, making it the List of United States cities by population, 28th most populous city in the United States, the sixth most populous on the West Coast of the United States, West Coast, and the third most populous in the Pacific Northwest after Seattle and Vancouver. Approximately 2.5 million people live in the Portland metropolitan area, Oregon, Portland metropolitan area, making it the List of metropolitan statistical areas, 26th most populous in the United States. Almost half of Oregon's population resides within the Portland metro area. Named after Portland, Maine, which is itself named aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Oswego, Oregon
Lake Oswego ( ) is a city in the U.S. state of Oregon, primarily in Clackamas County, with small portions extending into neighboring Multnomah and Washington counties. Population in 2020 was 40,731, an 11.2% increase since 2010, making it the 11th most populous city in Oregon. Located about south of Portland and surrounding the Oswego Lake, the town was founded in 1847 and incorporated as Oswego in 1910. The city was the hub of Oregon's brief iron industry in the late 19th century, and is today a suburb of Portland. History Early history The Clackamas people once occupied the land that later became Lake Oswego, but diseases transmitted by European explorers and traders killed most of the natives. Before the influx of non-native people via the Oregon Trail, the area between the Willamette River and Tualatin River had a scattering of early pioneer homesteads and farms. 19th century As settlers arrived, encouraged by the Donation Land Claim Act of 1850 and the subsequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oswego Lake
Oswego Lake is in Clackamas County, Oregon, United States, and is completely surrounded by the city of Lake Oswego, Oregon, Lake Oswego. Though the lake is naturally occurring (a former channel of the Tualatin River), it has been significantly altered because of the concrete dam that has increased its size to . The United States Geological Survey records the official name as ''Lake Oswego'' and, because of its artificially increased size, classifies it as a reservoir. To distinguish it from the city, however, the lake is usually called ''Oswego Lake''. Geologic history The lake is a Oxbow lake, former channel of the Tualatin River, carved in basalt to the Willamette River. Eventually, the river Meander, changed course and abandoned the Oswego route. About 13,000 to 15,000 years ago, the Proglacial lake, ice dam that contained Glacial Lake Missoula ruptured, resulting in the Missoula Floods, which backed the Columbia River up the Willamette River. The flooding created an underwate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbia River Gorge
The Columbia River Gorge is a canyon of the Columbia River in the Pacific Northwest of the United States. Up to deep, the canyon stretches for over as the river winds westward through the Cascade Range, forming the boundary between the state of Washington to the north and Oregon to the south. Extending roughly from the confluence of the Columbia with the Deschutes River (and the towns of Roosevelt, Washington, and Arlington, Oregon) in the east down to the eastern reaches of the Portland metropolitan area, the water gap furnishes the only navigable route through the Cascades and the only water connection between the Columbia Plateau and the Pacific Ocean. It is thus that the routes of Interstate 84, U.S. Route 30, Washington State Route 14, and railroad tracks on both sides run through the gorge. A popular recreational destination, the gorge holds federally protected status as the Columbia River Gorge National Scenic Area and is managed by the Columbia River Gorge Commis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wallula Gap
Wallula Gap () is a large water gap of the Columbia River in the Northwestern United States, in Southeastern Washington. It cuts through the Horse Heaven Hills basalt anticlines in the Columbia River Basin, just south of the confluence of the Walla Walla and Columbia rivers. The National Park Service has recognized the gap as a National Natural Landmark, as a site that provides an important illustration of the geological history of the United States. Geology Flood basalts In southeastern Washington, Eastern Oregon, and southern Idaho, flood basalt flows of extremely fluid basaltic lava spread in all directions from long fissures, building broad fields of gently sloping lava that spread widely over great distances. Along the Snake River in Idaho, and the Columbia River in Washington and Oregon, these lava flows have been extensively exposed by erosion (with extensive displays of columnar basalt), and measure almost in total thickness. The basalts flows which are visible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montana
Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, and the Provinces and territories of Canada, Canadian provinces of Alberta, British Columbia, and Saskatchewan to the north. It is the List of U.S. states and territories by area, fourth-largest state by area, but the List of U.S. states and territories by population, eighth-least populous state and the List of U.S. states and territories by population density, third-least densely populated state. Its List of capitals in the United States, capital is Helena, Montana, Helena, while the List of municipalities in Montana, most populous city is Billings, Montana, Billings. The western half of the state contains numerous mountain ranges, while the eastern half is characterized by western prairie terrain and badlands, with smaller mountain ranges f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
