The origin of prairies has occasioned much theory; it is to our mind very
simple: they are caused by the Indian custom of annually burning the
leaves and grass in autumn, which prevents the growth of any young trees.
Time thus will form prairies; for, some of the old trees annually perishing,
and there being no undergrowth to supply their place, they become thinner
every year; and, as they diminish, they shade the grass less, which
therefore grows more luxuriantly; and, where a strong wind carries a fire
through dried grass and leaves, which cover the earth with combustible
matter several feet deep, the volume of flame destroys all before it; the
very animals cannot escape. We have seen it enwrap the forest upon which
it was precipitated, and destroy whole acres of trees. After beginning;,
the circle widens every year, until the prairies expand boundless as the
ocean. Young growth follows the American settlement, since the settler
keeps off those annual burnings.
_American Quarterly Review_.
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