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Oxbow lake

2007 Schools Wikipedia Selection. Related subjects: Geology and geophysics

   Songhua River, northeast China. Swirls and curves, showing paths the
   river once took, as well as oxbow lakes, are easily seen in this
   satellite photo.
   Enlarge
   Songhua River, northeast China. Swirls and curves, showing paths the
   river once took, as well as oxbow lakes, are easily seen in this
   satellite photo.

   An oxbow lake is a type of lake which is formed when a wide meander
   from a stream or a river is cut off to form a lake. They are called
   oxbow lakes due to the distinctive curved shape that results from this
   process. In Australia, an oxbow lake is called a billabong.

Formation

   A Horseshoe or oxbow lake near Hughes, Arkansas, USA. The bulges in the
   border reflect changes in the course of the river; when the river
   shifted its course and cut off the former channel, the border did not
   change.
   Enlarge
   A Horseshoe or oxbow lake near Hughes, Arkansas, USA.
   The bulges in the border reflect changes in the course of the river;
   when the river shifted its course and cut off the former channel, the
   border did not change.

   When a river reaches a low-lying plain in its final course to the sea
   or a lake, it meanders widely. Deposition occurs on the convex bank
   because of the ‘slack water’, or water at low velocity. In contrast,
   both lateral erosion and undercutting occur on the concave bank where
   the stream’s velocity is the highest. Continuous erosion of a concave
   bank and deposition on the convex bank of a meandering river cause the
   formation of a very pronounced meander with two concave banks getting
   closer. The narrow neck of land between the two neighbouring concave
   banks is finally cut through, either by lateral erosion of the two
   concave banks or by the strong currents of a flood. When this happens,
   a new straighter river channel is created and an abandoned meander
   loop, called a cut-off, is formed. When deposition finally seals off
   the cut-off from the river channel, an oxbow lake is formed.

   Some rivers shift in this way on a time scale from a few years to
   several decades whereas others are essentially static.

Examples

   Early stages of formation of coastal plain ox-bow lake. Pembrokeshire,
   UK
   Enlarge
   Early stages of formation of coastal plain ox-bow lake. Pembrokeshire,
   UK
   Wee Tee Lake, Santee River valley, South Carolina
   Enlarge
   Wee Tee Lake, Santee River valley, South Carolina

   The Reelfoot Lake in west Tennessee is an oxbow lake formed when the
   Mississippi River changed course following the New Madrid Earthquake of
   1811– 1812. There are many oxbow lakes alongside the Mississippi River
   and its tributaries. The largest oxbow lake in North America, Lake
   Chicot (located near Lake Village, Arkansas), was originally part of
   the Arkansas River.

   Cuckmere Haven in Sussex, England contains a widely meandering river
   with many oxbow lakes, often referred to in physical geography
   textbooks.

   Retrieved from " http://en.wikipedia.org/wiki/Oxbow_lake"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
