The Great 

 Grass Sea 



The Steppes, Prairies, and Bottomlands 

 of the Central Plains and Plateau 



The whole central portion of this continent is covered by an 

 immensity of grasslands commonly called the Prairie Belt. 

 Today, real prairie of any extent without man-made adjuncts is 

 rare, for much of it has been subjected to agriculture, carved up 

 by a checkerboard of roads, or festooned with wire of all kinds. 

 Its countless bottomlands are also much farmed, and irrigation 

 is making tremendous strides all over its face. Its wildlife has 

 been very largely altered, in that the huge bison herds have all 

 gone and the number of the little prairie dogs has been greatly 

 reduced. This has brought great changes, but only a little greater 

 than those brought about by the creation of new exposed water 

 surfaces; these have introduced or caused visitation by many 

 other animals — mostly seasonal — that were previously scarce or 

 unknown. Some of these, such as the large Western Porcupine, 

 seem passing strange in an environment that appears to be far 

 removed from their normal one. 



Prairies appear in the interiors of large land masses and are 

 found in all of these— Eurasia, Africa, Australia, and even South 

 America. They develop where rainfall is lowered due to distance 

 from oceans, and particularly since large mountain masses in- 

 variably lie between them and the ocean from which the mois- 

 ture-laden prevailing winds blow. They are, in a way, temperate 

 deserts and share with such belts both daily and seasonal ex- 

 tremes of heat and cold. They are unsuited to tree growth, and 

 since they are usually covered with porous and uncompacted 

 sediments, they also fail to support shrubs. Perennial herbs make 

 use of seasonal rain but cannot stand prolonged droughts, so that 

 only grasses and certain kinds at that can survive upon them. 



Botanists have long debated the true status of grasslands — trop- 

 ical, temperate, and even those of the polar regions. There have 

 been two schools of thought. One contends that these grass belts 

 are a natural and permanent feature of the vegetational cover 

 of our earth and that their location is the result of fundamental 

 climatic factors. The other faction holds that all grasslands — 

 apart from small glades in woods and forests where the tree 

 growth has, for some reason, been inhibited — are man-made. 



The grass family was evolved comparatively late in the 



The White River Badlands, carved into the edge of the 

 prairie plateau, are among the most colorful and fantasti- 

 cally formed phenomena on this continent. 



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