Mesozoic and Cenozoic Geology and Paleontology. 185 
one case a continuous furrow was found 100 feet in length. The 
general direction of these scratches is N.N.E. and S.8.W. though they 
vary a little. One of the remarkable features of the country is a 
*‘ Lake ridge” passing through the four lake counties nearly parallel to 
the lake shore, and from four to eight miles distant from the lake, The 
width of the ridge at the base is from four to eight rods, and narrow- 
ing toward the top to only two or three rods in width. In many 
places it much exceeds this width, The elevation of this ridge above 
lake Ontario is from 160 to 200 feet, though it varies a little from this 
at some places. The whole of the ridge is superficial, being composed 
of sand, gravel and pebbles, in all respects similar to those forming 
the beaches along the present lakeshore. South of the ridge there are 
numerous parallel ridges, composed of sand and gravel, rising about 
25 to 35 feet above the general level, and having uniformly a north and 
south direction, but never crossing the lake ridge. The opinion ex- 
pressed in relation to this ridge is that it once constituted part of the 
shore of the lake, and consequently that the water in the lake was once 
160 or 200 feet higher than at present, and that the north and south 
ridges resulted from the overflow of the lake and the pouring out of 
its waters in a southerly direction. 
Prof. J. W. Foster* separated the surface deposits of Central Ohio 
into: 1. Vegetable mold; 2. Loam, or a mixture of sand and clay; 
3. Sand and pebbles; 4. Yellow clay; 5, Dark blue clay effervescing 
with acids. The whole of which has a thickness of from 950 to 150 feet. 
And also over the surface of the country there are scattered bowlders 
of granite, syenite, quartz, etc. In the region about Columbus, some 
of these erratic blocks contain 1,000 cubic feet. Not even a primitive 
pebble has been found on the highlands east of Zanesville, showing 
that the valley of the Muskingum formed a connection of the currents 
of water, that swept over the country, with the Ohio river. He de- 
scribed from an excavation for the canal at Nashport, Ohio, Casto- 
roides ohioensis. It was taken from a layer of dark carbonaceous silt, 
below a yellowish clay bed 14 feet in thickness, but above a layer of 
pebbles of primitive rocks and the blue clay at the bottom ofthe canal. 
Prof. John Locke found the surface of the rocks at Light’s quarry 
seven miles above Dayton, about 448 feet above the Ohio river at Cin- 
cinnati, planed, scratched and grooved. The quarry had _ been 
stripped of soil, more or less, over ten acres. The natural surface of 
the stone is very rough, and in some places this roughness was un- 
* Ohio Geo. Rep. 1838. 
pia Cg 5 
> ae Se 
