302 Observations on the Primitive Boulders of Ohio. 
erally more abrupt about Circleville than north of it. One eleva- 
tion near that place has been mistaken for an ancient artificial mound. 
In many places the soil is not very inviting to the agriculturist: only 
a stinted growth of oaks and hickories is to be met with. | Oceasion- 
ally a low place is too wet even for these and only a few sub-aquatic 
weeds and grasses are found. These last places become larger as 
we go northward and there assume the name of prairies. ‘The di- 
luvion extends to the lakes and probably some distance into Canada. 
The boulders occur most frequently in the beds of ravines and 
of rivers and the tops of hills. They seldom oceur on the surface 
of the diluvion where it remains entire’; but upon descending into 
the bed of some stream or rising a hill they may be seen in abun- 
dance. It would appear that the earth in these situations has been 
washed away leaving the more ponderous boulders exposed to view. 
At the Circleville bluffs the boulders were not allowed to form a 
part of the bank and were therefore collected in large piles by the 
workmen. Here then is an excellent opportunity for examining and 
comparing them. They also have the advantage of having been ta~ 
ken fresh from the bank, and are therefore free from the effects of 
the weather. We are not sufficiently familiar with the characters 
of primitive and transition rocks and the minerals which they contain, 
to undertake a description of each kind found here. This we have 
often regretted, as it would be quite interesting and highly useful in 
determining the precise localities from which they came. It is ho- 
ped that some more experienced geologist will ere long visit this lo- 
cality. Granite, gneiss, horblende rock, greenstone, argillite, &c. are 
mixed profusely with secondary rocks containing petrifactions of 
shells and madrepores. The largest boulder which we have seen 
was on the summit of a hill near Lancaster and was about six feet 
in length—we have heard of others much larger. 
Of the cause of this great flood which has at some very remote 
period swept down from the north and inundated the whole coun- 
try it would be in vain to speak. We are convinced that sucha flood 
has existed and that it has been the cause of the removal of our 
primitive fragments from their original beds. All the- facts eonneet- 
ed with the subject may be satisfactorily accounted for in this way- 
In an interesting paper by the Hon. Judge Tappan inserted in the 
14th Vol. of this Journal, it is stated that a variety of trap oF 
greenstone is the only rock which is found “rounded and smoothed 
by attrition,” and that these rarely occur, except “in the valleys of 
