386 H. Engelmann on vegetation known as 
. Occasionally, we also find as substrata a stiff rough clay, and at 
e points sand. 
The prairies all occupy the broad, more or less flat, dividing 
ridges between the streams. In digging wells on them, water 
are seldom reached in the prairies in digging wells, except near 
their borders, near the flats and barrens.’ The underlying for- 
sory causes may predominate so far as to seem alone to produce 
1s same result. : 
The prairies in the district under consideration have a very 
imperfect surface drainage, in consequence of their configuration. 
it absorbs direétly from the moist air. The first of these sources, 
the rain and melting snow, would cover the surface to an aver- 
* Remark.—In Washington county, which adjoins Perry county to the northward, a 
the same conditions of vegetation prevail, with the only difference tliat the prairies 
pro i broken — 
occupy a sti ion of in of the 0 
character of the land. re, rocks, mostly soft sandstones, have been struck at 
numerous points in digging wells in the prairies; but the water is generally ob- 
tained either above these rocks, so that only the well beds are in them,or 
else underneath a few layers merely of these rock then generally 
rather close to the surface, to only from 10 to 20 feet of it. In most of — 
then, t ill , 
Pee 
h is permeable to it, either throughout or locally in consequence of numerous 
‘bearing crevices. inpihtss-aemchaehe that oeabea second difference in the 
i . Point: 
‘emains 
at the end of this article. = ie 
i ‘on the ‘ Barrens’ and ‘ Sinks’ of Kentucky, by B. Silliman, 
Mammoth Cave, this Journal [2], xi, $83, 1850-—Eps] 
