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Kolk (vortex)
A kolk (colc) is an underwater vortex created when rapidly rushing water passes an underwater obstacle in boundary areas of high shear. High-velocity gradients produce a violently rotating column of water, similar to a tornado. Kolks can pluck multiple-ton blocks of rock and transport them in suspension for thousands of metres. Kolks leave clear evidence in the form of plucked-bedrock pits, called rock-cut basins or kolk lakes and 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 mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrodynamic Scour
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 scour, bridge failure and a problem with most marine structures supported by the seabed in areas of significant Tidal scour, tidal and ocean current. It can also affect biological ecosystems and heritage assets. Mechanism file:Kolkschema.svg, lang=en, upright=1.3, Mechanism of formation, alt=sketch 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 sha ... [...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 (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 in Spandau Borough, Berlin, Germany See also * Van der Kolk Van der Kolk is a Dutch toponymic surname, meaning "from/of the kolk". The surname Van der Wiel has a same origin. It could also have referred to a specific settl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Falls
Dry Falls is a scalloped precipice with four major alcoves, in central Washington scablands. This cataract complex is on the opposite side of the Upper Grand Coulee from the Columbia River, and at the head of the Lower Grand Coulee, northern end of Lenore Canyon. According to the current geological model, catastrophic flooding channeled water at 65 miles per hour (105 kph) through the Upper Grand Coulee and over this rock face at the end of the last glaciation. It is estimated that the falls were five times the width of Niagara Falls, with ten times the flow of all the current rivers in the world combined. Nearly twenty thousand years ago, as glaciers moved south through North America, an ice sheet dammed the Clark Fork River near Sandpoint, Idaho. Consequently, a significant portion of western Montana flooded, forming the gigantic Lake Missoula. About the same time, Glacial Lake Columbia was formed on the ice-dammed Columbia River behind the Okanogan lobe of the Cordillera ... [...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, Oregon, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland, Oregon
Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous county in Oregon. Portland had a population of 652,503, making it the 26th-most populated city in the United States, the sixth-most populous on the West Coast, and the second-most populous in the Pacific Northwest, after Seattle. Approximately 2.5 million people live in the Portland metropolitan statistical area (MSA), making it the 25th most populous in the United States. About half of Oregon's population resides within the Portland metropolitan area. Named after Portland, Maine, the Oregon settlement began to be populated in the 1840s, near the end of the Oregon Trail. Its water access provided convenient transportation of goods, and the timber industry was a major force in the city's early economy. At the turn of the 20th century, the ... [...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. 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. The population in 2010 was 36,619, a 3.8% increase over the 2000 population of 35,278. 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 Homestead Act, they found the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oswego Lake
Oswego Lake is a lake in Clackamas County, Oregon that is completely surrounded by the city of 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 former channel of the Tualatin River, carved in basalt to the Willamette River. Eventually, the river changed course and abandoned the Oswego route. About 13,000 to 15,000 years ago, the 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 underwater vortex called a kolk, which scoured out and enlarged the old O ... [...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 Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wallula Gap
Wallula Gap () is a large water gap of the Columbia River in the northwest United States in southeast 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. It has been recognized as a National Natural Landmark by the National Park Service 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 2 km (1.24 mi) in total thickness. The basalts fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montana
Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbia, and Saskatchewan to the north. It is the fourth-largest state by area, the eighth-least populous state, and the third-least densely populated state. Its state capital is Helena. The western half of Montana contains numerous mountain ranges, while the eastern half is characterized by western prairie terrain and badlands, with smaller mountain ranges found throughout the state. Montana has no official nickname but several unofficial ones, most notably "Big Sky Country", "The Treasure State", "Land of the Shining Mountains", and " The Last Best Place". The economy is primarily based on agriculture, including ranching and cereal grain farming. Other significant economic resources include oil, gas, coal, mining, and lumber. The health ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hellgate Canyon (Montana)
Hellgate Canyon is a canyon in Missoula County, Montana, formed by the Clark Fork River. It is located just to the east of Missoula, and is approximately fifty miles long. The entrance to the canyon is known as Hell's Gate. Name Hellgate Canyon's name is a reference to an ambush that occurred there, in which the Flathead Indians were defeated by the Blackfeet. The evidence of these ambushes was known as the "gates of hell", which led to the canyon acquiring its current name. Historical significance Hellgate Canyon contains some ancient pictographs estimated to be about 5,000 years old. Lewis and Clark passed through Hellgate Canyon during their expedition through the Western United States. Later in the 19th century, Carrie Strahorn, also an explorer, wrote about a stagecoach ride she took in the area in 1878. She described, among other things, a "veritable Lover’s Lane" formed above the canyon by an arch of wild roses. During the mid-19th century, as Montana was further c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clark Fork River
The Clark Fork, or the Clark Fork of the Columbia River, is a river in the U.S. states of Montana and Idaho, approximately long. The largest river by volume in Montana, it drains an extensive region of the Rocky Mountains in western Montana and northern Idaho in the watershed of the Columbia River. The river flows northwest through a long valley at the base of the Cabinet Mountains and empties into Lake Pend Oreille in the Idaho Panhandle. The Pend Oreille River in Idaho, Washington, and British Columbia, Canada which drains the lake to the Columbia in Washington, is sometimes included as part of the Clark Fork, giving it a total length of , with a drainage area of . In its upper in Montana near Butte, it is known as Silver Bow Creek. Interstate 90 follows much of the upper course of the river from Butte to Saint Regis. The highest point within the river's watershed is Mount Evans at in Deer Lodge County, Montana along the Continental Divide. The Clark Fork is a Class I rive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
