68 
The Ohio Xaturalist. 
[Vol. IV, No. 3 , 
the bone bed or top of the formation. As the quarry is at about 
the top of the hill it is probable that this bed has been carried 
awa}^ for some feet back from the brow of the bluff into the field. 
It might be wished that this layer were present to give a more 
certain determination, but as the interval between the smooth 
layer and the bone bed is fairly constant the presence of the lat- 
ter is not so important as would appear at first. 
The sections of the hill and well are given in the tables. It 
will be seen that the total thickness of the Columbus exposed is 
109 feet. Assuming an interval between the bone bed and smooth 
bed of 9 feet fan inch or two less than that shown in the quarries 
a mile and a half below the dam site ), we would have a thickness 
for the formation of no feet, thus checking to within 2 feet of 
the determination from the State House 3'ard well. 
Section of Bank. Feet. In. 
To bone bed (not expo.sed) ?i 2 
Top of quarr}-, no sign of bone bed . . 
Upper Columbus exposed in quarry 8 . . 
Smooth laver 
Quarre- e.xtends a few inches below smooth layer 
INIostly covered, occasional ledges exposed to river level 64 
Section of Well. 
Gravel and soil 2 
River level 
Gravel and soil to top of rock 2 7 
Heavy bedded some la3'ers come out more than 2 feet 
tfiick 24 8 
Thin bedded much waste in core 7 2 
IIeav3’ porous breccia, base of Columbus 2 4 
Hard course with dark bands top of Monroe 8 
Mostly thin bedded, dark 3 10 
Purer lime.stone 9 
Dark thin bedded resisting acid i 
White, purer stone 9 
Hea\'3' bedded i 9 
Dark, vert- hard resisting acid 6 
Hard, heavw, dark stone with little waste 7 
Total 
Feet. In, 
126 2 ? 
125 
IJ7 
53 . 
55 
53 
53 
50 5 
25 9 
10 3 
15 7 
11 9 
II 
10 
9 3 
7 6 
7 
The determination is subject to the following .sources of error : 
I , waste in the core of the well which would have the effect of 
making the base of the Columbus too high with a maximum 
value of 2 inches ; 2, a variation in the level of the water between 
the time of boring the well and that of measuring the hill amoun- 
ing to po-ssibh’ 6 inches in the other direction ; 3, errors in level- 
ing amounting to possibl3' 3 feet either wa3’ ; the cit3* contour 
maps check the leveling and preclude the pos.sibilit3’ of greater 
error, i. c., the top of the quarr3' lies between two contour lines 
having a five foot interval ; 4, variation in the interval between 
the smooth bed and bone bed with a probable maximum of 8 
inches. 
P'argo, X. D. 
