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Created page with 'File:lighterstill.jpgright|frame '''Plains''' refer to the relatively smooth sections of the continental surfaces, occ...'
[[File:lighterstill.jpg]][[File:The-Plains-Near-Kilimanjaro-1.jpg|right|frame]]

'''Plains''' refer to the [[relatively]] smooth sections of the [[continental]] [[surfaces]], occupied largely by [[gentle]] rather than steep slopes and exhibiting only small local [[differences]] in elevation. Because of their smoothness, plains [[lands]], if other conditions are favorable, are especially amenable to many [[human]] [[activities]]. Thus it is not surprising that the [[majority]] of the world's principal [[agricultural]] regions, close-meshed [[transportation]] networks, and [[concentrations]] of [[population]] are found on plains. Large parts of the [[Earth]]'s plains, however, are hindered for [[human]] use by [[Aridity|dryness]], shortness of frost-free [[season]], infertile [[soils]], or poor drainage. Because of the [[absence]] of major differences in elevation or [[exposure]] or of obstacles to the [[free]] movement of [[air]] masses, extensive plains usually exhibit broad [[uniformity]] or [[gradual]] [[transition]] of [[climatic]] characteristics.

Somewhat more than one-third of the [[Earth]]'s [[land]] area is occupied by plains. With the exception of [[ice]]-sheathed [http://en.wikipedia.org/wiki/Antarctica Antarctica], each continent contains at least one major expanse of smooth [[land]] in addition to numerous smaller areas. The largest plains of [http://en.wikipedia.org/wiki/North_America North America], [http://en.wikipedia.org/wiki/South_America South America], and [http://en.wikipedia.org/wiki/Eurasia Eurasia] lie in the [[continental]] interiors, with broad extensions reaching to the Atlantic (and Arctic) Coast. The most extensive plains of [http://en.wikipedia.org/wiki/Africa Africa] occupy much of the [http://en.wikipedia.org/wiki/Sahara Sahara] and reach south into the [http://en.wikipedia.org/wiki/Congo Congo] and [http://en.wikipedia.org/wiki/Kalahari Kalahari] basins. Much of [http://en.wikipedia.org/wiki/Australia Australia] is smooth, with only the eastern margin lacking extensive plains.

[[Surfaces]] that approach true flatness, while not rare, [[constitute]] a minor portion of the world's plains. Most commonly they occur along low-lying coastal margins, the lower sections of major [[river]] systems, or the floors of inland basins. Nearly all are the products of extensive deposition by [[streams]] or in lakes or shallow [[seas]]. The [[majority]] of plains, however, are distinctly irregular in [[surface]] form, as a result of valley-cutting by [[streams]] or of irregular [[erosion]] and deposition by continental [[glaciers]].[http://www.answers.com/main/ntquery?s=plains&gwp=13]

[[Category: Geography]]

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