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River Rejuvenation
In geomorphology a river is said to be rejuvenated when it is eroding the landscape in response to a lowering of its base level. The process is often a result of a sudden fall in sea level or the rise of land. The disturbance enables a rise in the river's potential energy, increasing its riverbed erosion rate. The erosion occurs as a result of the river adjusting to its new base level. Signs River rejuvenation can lead to a number of changes in landscape. These include the formation of waterfalls and rapids, knick points, river terraces and incised meanders. Rejuvenated terrains usually have complex landscapes because remnants of older landforms are locally preserved. Parts of floodplains may be preserved as terraces alongside the down-cutting stream channels. Meandering streams may become entrenched, so a product of older river systems is found with steep, very pronounced "V" shaped valleys - often seen with younger systems. Example One ancient example of rejuvenation is the Ni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incised Meander
A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex bank which is typically a point bar. The result of this coupled erosion and sedimentation is the formation of a sinuous course as the channel migrates back and forth across the axis of a floodplain. The zone within which a meandering stream periodically shifts its channel is known as a meander belt. It typically ranges from 15 to 18 times the width of the channel. Over time, meanders migrate downstream, sometimes in such a short time as to create civil engineering challenges for local municipalities attempting to maintain stable roads and bridges.Neuendorf, K.K.E., J.P. Mehl Jr., and J.A. Jackson, J.A., eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Charlton, R., 2007. ''Fundamentals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluvial Geomorphology
In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used. Fluvial processes Fluvial processes include the motion of sediment and erosion or deposition on the river bed. The movement of water across the stream bed exerts a shear stress directly onto the bed. If the cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. In addition, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed ( abrasion). At the same time the fragments themselves are ground down, becoming smaller and more rounded (attrition). Sediment in rivers is transported as either bedload (the coarser frag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluvial Terrace
Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplain, other fluvial terraces, or uplands by distinctly steeper strips of land called "risers". These terraces lie parallel to and above the river channel and its floodplain. Because of the manner in which they form, fluvial terraces are underlain by fluvial sediments of highly variable thickness.Fairbridge, R. W., 1968, ''Encyclopedia of Geomorphology.'' Reinhold Book Company, New York.Blum, M., and T.E. Tonqvist, 2000, ''Fluvial responses to climate and sea-level change, a review and look forward.'' Sedimentology. v. 47 suppl. 1, pp. 2-48. River terraces are the remnants of earlier floodplains that existed at a time when either a stream or river was flowing at a higher elevation before its channel downcut to create a new floodplain at a lower elevation. Changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knickpoint
In geomorphology, a knickpoint or nickpoint is part of a river or channel where there is a sharp change in channel slope, such as a waterfall or lake. Knickpoints reflect different conditions and processes on the river, often caused by previous erosion due to glaciation or variance in lithology. In the cycle of erosion model, knickpoints advance one cycle upstream, or inland, replacing an older cycle. A knickpoint that occurs at the head (furthest upstream extent) of a channel is called a headcut. Headcuts resulting in headward erosion are hallmarks of unstable expanding drainage features such as actively eroding gullies. Knickpoints also occur on other planetary bodies that previously had or currently have surface liquids, namely Mars and Titan. On Mars, the knickpoints have a common elevation that suggest a common sea level for a former Martian ocean. On Titan, mountain valleys adjacent to the present-day hydrocarbon seas show evidence of knickpoints and recent sea-level ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Erie
Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. At its deepest point Lake Erie is deep. Situated on the International Boundary between Canada and the United States, Lake Erie's northern shore is the Canadian province of Ontario, specifically the Ontario Peninsula, with the U.S. states of Michigan, Ohio, Pennsylvania, and New York on its western, southern, and eastern shores. These jurisdictions divide the surface area of the lake with water boundaries. The largest city on the lake is Cleveland, anchoring the third largest U.S. metro area in the Great Lakes region, after Greater Chicago and Metro Detroit. Other major cities along the lake shore include Buffalo, New York; Erie, Pennsylvania; and Toledo, Ohio. Situated below Lake Huron, Erie's p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niagara Falls
Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the province of Ontario in Canada and the state of New York in the United States. The largest of the three is Horseshoe Falls, which straddles the international border of the two countries. It is also known as the Canadian Falls. The smaller American Falls and Bridal Veil Falls lie within the United States. Bridal Veil Falls is separated from Horseshoe Falls by Goat Island and from American Falls by Luna Island, with both islands situated in New York. Formed by the Niagara River, which drains Lake Erie into Lake Ontario, the combined falls have the highest flow rate of any waterfall in North America that has a vertical drop of more than . During peak daytime tourist hours, more than of water goes over the crest of the falls every minute. Horseshoe Falls is the most powerful waterfall in North America, as measured by flow rate. Niagara Falls is famed for its b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iceland
Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its surrounding areas) is home to over 65% of the population. Iceland is the biggest part of the Mid-Atlantic Ridge that rises above sea level, and its central volcanic plateau is erupting almost constantly. The interior consists of a plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate. According to the ancient manuscript , the settlement of Iceland began in 874 AD when the Norwegian chieftain Ingólfr Arnarson became the first p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seljalandsfoss
Seljalandsfoss () is a waterfall in Iceland. Seljalandsfoss is located in the South Region in Iceland right by Route 1 and the road that leads to Þórsmörk Road 249. The waterfall drops and is part of the Seljalands River that has its origin in the volcano glacier Eyjafjallajökull. Visitors can walk behind the falls into a small cave. Controversy Plans to build an 8-metre high, 2000 square-metre information centre near the waterfall provoked controversy in Iceland in May 2017. Opponents of the plans argued that the building would spoil the view of the waterfall and interrupt the natural look of the area. In popular culture Seljalandsfoss was a waypoint during the first leg of ''The Amazing Race 6''. Seljalandsfoss was featured in the movie ''CKY2K'' along with music from Björk. A scene from the 1990 movie The Juniper Tree (film) has Björk's character walk behind the waterfall. The official music video of "I'll Show You" by Justin Bieber features glacial lagoons a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudie, A. S., 2004, ''Encyclopedia of Geomorphology'', vol. 1. Routledge, New York. The soils usually consist of clays, silts, sands, and gravels deposited during floods. Because the regular flooding of floodplains can deposit nutrients and water, floodplains frequently have high soil fertility; some important agricultural regions, such as the Mississippi river basin and the Nile, rely heavily on the flood plains. Agricultural regions as well as urban areas have developed near or on floodplains to take advantage of the rich soil and fresh water. However, the risk of flooding has led to increasing efforts to control flooding. Formation Most floodplains are formed by deposition on the inside of river meanders and by overbank flow. Whereve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluvial Terrace
Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplain, other fluvial terraces, or uplands by distinctly steeper strips of land called "risers". These terraces lie parallel to and above the river channel and its floodplain. Because of the manner in which they form, fluvial terraces are underlain by fluvial sediments of highly variable thickness.Fairbridge, R. W., 1968, ''Encyclopedia of Geomorphology.'' Reinhold Book Company, New York.Blum, M., and T.E. Tonqvist, 2000, ''Fluvial responses to climate and sea-level change, a review and look forward.'' Sedimentology. v. 47 suppl. 1, pp. 2-48. River terraces are the remnants of earlier floodplains that existed at a time when either a stream or river was flowing at a higher elevation before its channel downcut to create a new floodplain at a lower elevation. Changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Potential Energy
Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (converted into kinetic energy) when the objects fall towards each other. Gravitational potential energy increases when two objects are brought further apart. For two pairwise interacting point particles, the gravitational potential energy U is given by U = -\frac, where M and m are the masses of the two particles, R is the distance between them, and G is the gravitational constant. Close to the Earth's surface, the gravitational field is approximately constant, and the gravitational potential energy of an object reduces to U = mgh where m is the object's mass, g = / is the gravity of Earth, and h is the height of the object's center of mass above a chosen reference level. Newtonian mechanics In classical mechanics, two or more masse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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