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the valley's shoulders often make the characteristic difference of V- and U-shaped hillsides]] The terms U-shaped and '''V-shaped''' are descriptive terms of Geography to characterize the form of Valley s. Most of the mountainous valleys, Glen s or Dale s belong to these two main types or a mixture of them, at least with respect of the Cross-section of the slopes or Hillside s. Other (more special) types are e.g. the Clammy (steep Cliff s), the Hollow -formed hillsides and river Plain Valley s, mostly with a broad River Bed . TWO MOUNTAINOUS VALLEY TYPES A V-shaped valley is a narrow valley with steep walls ( Slope s) and a narrow Valley Bottom with a stream Channel . The valley shape resembles a ''V'' in cross section. It is created by fast flowing Brook s or rivers with steep gradients. Flowing downhill quickly, it removes more sediment from the stream channel bottom than from the sides. This " Downcutting " can be compared to a knife cutting through a cake. The resulting landform is a narrow canyon with fast water and little bank ( Floodplain ) on the river sides. A lot of examples are found in many Mountain Range s; some broad ''V'' examples are:
An U-shaped valley has a flat or slightly rounded floor and Steepen ed slopes, both formed by glaciers flowing downhill (''not'' by the river presently existing here). Glacially carved valleys are called U-shaped for in cross section they resemble the letter ''U''. Floor gradient does not affect the valley's shape, it is the glacier's size that does. Continuously flowing glaciers - espec. in the Ice Age - and large sized glaciers carve wide, deep incised valleys. Examples of U-valleys are found are found in every mountainous region with Glacial Period s - like the Alps or Rocky Mountains but also in Scotland , Scandinavia or Canada . Much interesting are the
GENESIS (V BECOMES U) AND RIVER PLAIN VALLEYS in Montana , United States .]] ''V-shaped valleys'' are the rather Original landforms crated by alpine rivers, due to a drastic Erosion of the valley Slope s (mountain sides) which is called Denudation . However, ''U-shaped valleys'' (in German "Trogtal" = ) and near his edges (see border- or Lateral Moraine ). In many cases this edge is approx. Halfway up - which forms the later Valley Shoulder s. Below them the slope inclination has a maximum (see 2nd figure). Because at any time glaciers came into most alpine valleys of the northern hemisphere, the U-type is more frequent. Just at very narrow or "young" valleys the V-type is predominant. However, River plain valleys are typical for the Lower Reaches of rivers. They have broad flat Valley Floor s with sides of varying angles (usually more shallow near to the Ocean). The valley bottom is formed by a Meander ing river. Plain valleys are created by slow moving rivers flowing at moderate to low angle slopes. A river at this gradient tends to erode more along the sides of the channel than along the bottom. Thus, the river slowly sweeps across the valley floor, forming a broad river Plain . TRANSITION FORMS AND VALLEY SHOULDERS Depending on the . /Utah with very striking shoulders]] In some stress-tectonic regions of the Rockies or the Alps (e.g. Salzburg ) the Side Valley s are parallel to each other, and additionally they are Hanging . The brooks flow into the River in form of deep Gorge s or Waterfall s. Usually this fact is the result of a violent erosion of the former valley shoulders. A special genesis we find also at Arete s and glacial Cirques , at every Scottish Glen , or a northern Fjord . EXTERNAL LINKS
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