208 Notes on the Drift and Alluvium of Ohio and the West. 
Ohio River drift, contains all the varieties of rocks known in 
North America. The city of Cincinnati stands upon a plain of 
this sort, elevated in benches or steps—the first about 60, the se- 
cond 9U to 120 feet above low water. 
It is sometimes difficult to distinguish this drift from the ordi- 
nary recent deposits or alluvium of the streams. On its surface 
are seen longitudinal ridges like these around the lakes, but less 
reguiar, and much less continuous. They are narrower, not as 
level, steeper at the sides, and short. 
No. V. Meposits of the Lake Basin.—Mr. Featherstonehaugh 
gave these deposits the name of “lacustrine,” which is probably 
correct, As yet however [ am not aware of any well authentica- 
ted case of fossil shells found in them, though there are some of 
shells found in alluvium upon them. The descripticns given by the 
New York geologists, of the tertiary clays of the Hudscn and of 
Lake Champlain, correspond closely with the external characters 
of the two members of the Lake Erie deposits. The “ Pest-pli- 
ocene tertiary” of New York, is first, stiff blue clay ; second, yel- 
lowish brown clay ; third, yellowish brown sand. The greatest 
height above the ocean, in the Champlain tertiary, is about 400 
feet, or 164 feet below the present level of Lake Erie. In New 
York, marine shells are abundant; here neither fresh nor salt- 
water shells have been found. On the St. Lawrence, marine 
shells are numerous in the drift beds near Montreal, at an eleva- 
tion of 540 feet above tide, but still below the present level of 
Lake Erie. In the diluvial clays and drift of New York and the 
St. Lawrence, primitive boulders of large size appear to be com- 
mon; while here, none of large size are seen, so far as I am in- 
formed, and few of a small size. 
The blue “marly sand,” commonly called the “blue clay” of 
Lake Erie, is seen skirting the shore almost every where, if the 
coast is not rocky,—its upper face nearly horizontal, and rising 
from forty-five to sixty feet above the water. It is of a light 
blue color, so fine as scarcely to show between the fingers any 
grit, homogeneous, and ina dry state compact, but brittle. Very 
rarely, may be seen a primitive pebble, thin layers of leaves, and 
lignite. It is distinctly and horizontally laminated, and at Cleve- 
land is composed of about 75 per cent. impalpable sand, 3 per 
cent. iron, 6 to 7 per cent. carbonate of lime, 9 per cent. carbon- 
ate of magnesia, and of vegetable matter and sulphur. It is im- 
pervious to water, and thus causes thousands of springs to appear 
at its surface, which passing out over the edges, dissolve and carry 
it away very fast, forming a quicksand. Its edge is presented to 
the action of the waves, which dissolve and carry it away rap- 
idly. As it is not tenacious like clay, and not capable of sus- 
taining itself under its own weight, and that of the sand stratum 
that rests upon it, there are continual breaks and slides along the 
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