Coulee


Coulee
An upwards view of section of the wall protruding to the canyon. There is a marsh in the foreground.
A view through a coulee, with steep but lower sides, and water in the bottom.
Drumheller Channels in the Columbia Basin of Washington
A view upward into a coulee in the Oldman River valley in Lethbridge, Alberta

Coulee (or coulée) is applied rather loosely to different landforms, all of which refer to a kind of valley or drainage zone.

The word coulee comes from the Canadian French coulée, from French word couler meaning "to flow".

The term is often used interchangeably in the Great Plains for any number of water features, from ponds to creeks.

In southern Louisiana the word coulée (also spelled coolie) originally meant a gully or ravine usually dry or intermittent but becoming sizable during rainy weather. As stream channels were dredged or canalized, the term was increasingly applied to perennial streams, generally smaller than bayous. The term is also used for small ditches or canals in the swamp.[1]

Contents

Types and examples

  1. The dry, braided channels formed by glacial drainage of the Scablands of eastern Washington, such as Grand Coulee and Moses Coulee.
  2. The furrowed moraines channeling rain runoff in the area east of the Coteau du Missouri in the western United States and western Canada at the base of the Rocky Mountains.
  3. In the western United States, tongue-like protrusions of solidified lava, forming a sort of canyon.
  4. In Wisconsin, it is applied to smaller sometimes intermittent tributary streams in the watershed of the Upper Mississippi River, north of the Wisconsin River and as far up as the Saint Croix River. These valleys tend to have high, steep walls. "Hollow" is used as a synonym, often for the smallest of such valleys. The term is also applied to the greater La Crosse, Wisconsin metropolitan area, rather much like "Twin Cities" is applied to Minneapolis-Saint Paul. The term has also been incorrectly applied to the whole of the Driftless Area, when in fact the Coulee Region excludes portions of the Driftless, while including portions which are outside of it.

In some parts of Louisiana coulees are not concreted but rather sheer sided large ditches that collect smaller ditch runoff.

Geomorphology

Aside from those formed by volcanic eruptions, they are commonly canyons characterized by steep walls that have been shaped by erosion. These types of coulees are generally found in the northwestern United States and southwestern Canada. In the American west, rapid melting of glaciers at the end of the last ice age caused catastrophic flooding which removed bedrock by massive down-cutting erosion, forming deep canyons. Some coulees may be seasonally dry or contain small streams, however these small streams do not have the magnitude of force necessary to form such expansive erosion.

In Wisconsin, they are the product of nearly a half million years of erosion, unmodified by glaciation (see Driftless Area[2]). The loose rocks at the base of the wall form what are called scree slopes. These are formed when chunks of the canyon wall give way in a rockslide. Left alone, the valleys are often woodland, with the ridgetops transitioning into tallgrass prairie when not turned into pasture or used for row crops.

Coulees provide shelter from wind and concentrated water supplies to plants which would otherwise struggle to survive in the xeric sagebrush steppe. Trees are often found in riparian habitats along streams in coulees and at the base of their walls.

[3]

References

  1. ^ Edwards, Jay Dearborn; Nicolas Kariouk Pecquet du Bellay de Verton (2004). A Creole lexicon: architecture, landscape, people. Louisiana State University Press. p. 73. ISBN 9780807127643. http://books.google.com/books?id=EY5E5bp9KGwC&pg=PA73. Retrieved 15 July 2011. 
  2. ^ Cotton Mather, "Coulees and the coulee country of Wisconsin", pp. 22-25, Wisconsin Academy Review, September 1976 (James R. Batt, (ed.)), Retrieved July 26, 2007
  3. ^ Easterbrook, Don J. (1999). Surface Processes and Landforms. Prentice Hall, Upper Saddle River New Jersey. Pp. 381-385

See also


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Look at other dictionaries:

  • coulée — [ kule ] n. f. • 1611; de couler 1 ♦ (1845) Action de jeter en moule. La coulée d un métal. Surveiller la coulée. Masse de matière en fusion que l on verse dans un moule. Trou de coulée. 2 ♦ Action de s écouler; son résultat. Une coulée de lave.… …   Encyclopédie Universelle

  • coulée — COULÉE. s. f. Terme d Écriture. Caractère d écriture penché, dont toutes les lettres se tieunent, et qu on appelle Coulée, distinguée de la Ronde. Il est aussi adjectif fémin. Une écriture coulée …   Dictionnaire de l'Académie Française 1798

  • coulee — deep ravine, seasonally flooded, 1804, a N.Amer. word, originally in areas explored by French trappers, from Fr. coulée flow (17c.), from fem. pp. of couler to flow, from L. colare to filter, strain …   Etymology dictionary

  • coulee — [ko͞o′lē] n. [Fr coulée < couler, to flow < L colare, to strain: see COLANDER] 1. a stream of molten lava or a sheet of solidified lava ☆ 2. Northwest a deep gulch or ravine, usually dry in summer …   English World dictionary

  • Coulee — Cou lee (k?? l? ), n. [F. coul[ e]e, fr. couler to run or flow.] A stream; (Geol.) a stream of lava. Also, in the Western United States, the bed of a stream, even if dry, when deep and having inclined sides; distinguished from a ca[ n]on, which… …   The Collaborative International Dictionary of English

  • Coulée — (fr., spr. Kuleh), eine französische Schreibschrift, deren Züge nach rechts geneigt liegen, s. Schrift …   Pierer's Universal-Lexikon

  • Coulée — Coulée, liegende Schreibschrift der Franzosen …   Herders Conversations-Lexikon

  • Coulée — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Coulée de lave, épanchement de laves issue d un volcan ou d une fissure en contexte volcanique ; Coulée pyroclastique, phénomène d avalanche composée …   Wikipédia en Français

  • coulée — (kou lée) s. f. 1°   Action de couler. La coulée d une lessive. La coulée des laves d un volcan. 2°   Opération du coulage d un métal.    Flot de lave, de métal ou de verre à l état de fusion. •   Il paraît que ces déjections [du Vésuve] n… …   Dictionnaire de la Langue Française d'Émile Littré

  • coulée — nf. ; action de couler, pression, (d un pressoir à huile, vin blanc ou rosé, cidre...) ; passage à l alambic ; glissement de terre, de lave, de boue, de neige ; avalanche ; coulée de lessive : KOLÂ nf. (Albanais.001, Annecy, Cordon.083, Giettaz,… …   Dictionnaire Français-Savoyard


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