234 Prairies of Ohio. 
while they have never been found upon their surface. It is said 
they are scattered over the wet prairies of Champaign county, Ohio, 
but if so, these are entirely different in character from the prairies 
I have attempted to describe. They must have been formed upon 
the bed of some ancient lake, after its waters had escaped, while 
those to which I have so often referred, were the offspring of a fill- 
ing up of a former basin, by the debris of the adjacent elevations, 
assisted by the peat moss of their waters, and the timber and re- 
mains of animals brought into them by the streams. It is in this 
manner that the small lakes in the interior of wet prairies are now 
gradually disappearing. At first, the water leaves a kind of shaking 
bog, similar to those already mentioned, but this eventually loses its 
humid character, and presents a deep black mould, differmg in no 
respect from that found elsewhere in the low lands. The woody 
islands, or many of them, at least, were once undoubtedly surround- 
ed by water, which must have beat against their shores for a long 
time ; for if this were not the case, the quartz pebbles could never 
have either reached their present locations, or been reduced to a 
rounded form. It certainly required much water, time and attrition, 
to perform so important a change. ‘The pebbles could not have 
been driven over the prairie, for none such are found upon its sur- 
face. Blocks, or large bowlders of granite, have been detected, 
when boring, deep beneath a wet prairie soil. ‘These must have 
been transported here at the time the same species were lodged upon 
the surface of the surrounding country. The basin of the prairie 
must also have been filled with water, at that period, otherwise they 
could not have descended so far beneath the surface. 
But wet prairies do not remain such continually. Many of the 
causes which aided in their formation, are now contributing much 
towards their destruction. ‘The debris, consisting of sand, gravel, 
and clay, of the higher lands, is gradually converting their borders 
into.a sandy soil, followed by a growth of timber, and other vegeta- 
bles, peculiar to the upper lands. At first the ligneous productions 
consist principally of a variety of hazel and oak, none of which at- 
tainalargesize. ‘This growth, however, soon gives place to another, 
which continues to extend until a dark forest has taken the place of 
grass and flowers. 
Cultivation also contributes much to the destruction of prairies, 
by the introduction of grasses and plants essentially different from 
