188 Cincinnati Society of Natural History. 
Grooves or strize are found upon the surface of all the rocks beneath 
the drift in the fourth district, which are of sufficient hardness to re- 
ceive and retain such impressions. From the Medina sandstone, at the 
level of lake Ontario, to the summit of the Carboniferous conglomer- 
ate, in the southern part of the State, some of the strata in every group 
bear upon their surface these markings of former abrasion, -and 
evidence of moving force. The direction of these strize vary but few 
degrees from N. 35° E. and 8, 35° W. in their general course. Short 
and shallow strie are abundant, which vary ten and fifteen degrees 
from this direction, but these have no continuous course, and apparent- 
ly fall into the main direction after a few feet. These markings range 
from the slightest possible scratch, to grooves of half an inch in width 
and one fourth of an inch in depth. The grooves seem to have been 
made by a hard substance, moved with great force and under great. 
pressure, for fragments are found broken out as the grooves approach a 
fissure in the strata, as if crushed out by some heavy body, and some- 
times the grooves are observed following, somewhat obliquely, the 
fractured slope. The outcropping edges of strata, previously polished 
and grooved, are often found overturned, upon the rock, in place. 
At Rochester, the surface of the limestone is finely striated, and al- 
most perfectly polished by the abrading force. The material here rest- 
ing upon the rock is fine sandy loam; in another locality a mile farther 
south, it is covered by coarse limestone gravel and sandstone pebbles, 
with bowlders of granite. The striz here are N.N.E. and $.S.W. At 
Black Rock, the surface of the Corniferous limestone shows that the 
nodules of hornstone interrupted the progress of the striz and stand 
above the surrounding polished surface. The direction here is N. 15° 
E. and 8. 35° W. At the cliff of Lake Erie in Portland, Chautauqua 
county, the rocky strata below have been uplifted, broken and con- 
torted; the fragments intermingled with clay and gravel, and the same 
pressed beneath the strata, which otherwise appear to be in place. 
The terrace at Lewiston is formed by the upper part of the Medina 
sandstone, the Clinton Group and the Niagara shale, capped by about 
twenty feet of Niagara limestone. The top of this terrace is 350 feet 
above Lake Ontario, and more than 200 feet above the plain about 
Lewiston. The Niagara shale is carried away so as to leave the lime- 
stone of the Clinton Group torming a projecting shelf about 100 feet 
below the top of the terrace. The surface of this projecting shelf is 
deeply grooved and striated, the grooves having a general southern 
tendency, but more irregular than where they are seen upon the lime- 
