230 Cincinnati Society of Natural History. 
Commencing in the lower tier of counties in the State of New York 
where the hills are from 600 to 800 feet above the level of the narrow 
valleys, as they occur in Cattaraugus, Alleghany, Steuben and Chemung 
counties, and extending South over all the highlands of Pennsylvania, 
and over Virginia, West Virginia, the Carolinas, and the eastern 
parts of Kentucky and Tennessee, and South to the Gulf of Mexico, 
we have an absolutely driftless area; an area of dry land when the . 
marine clays and sands were strewn over the territory adjacent to the 
Gulf of St. Lawrence, and over the New Eugland States; and also an 
area of dry land during the period of the drift, of the central part of 
the continent, and for untold geological ages antecedent thereto. The 
elevated hills, precipitous ledges, profound valleys, overhanging rocks, 
and castellated outliers of the Carboniferous conglomerate in Cat- 
taraugus county, some of which are illustrated in the Geology of 
McKean county, in the Report of Progress R. of the Second Geological 
Survey of Pennsylvania, under the name of the Olean conglomerate at 
Rock City, furnish the most incontestible evidence of the ordinary 
eroding agents through a period of time, commencing long anterior to 
the Tertiary epoch, and equally as conclusive evidence that no glacier 
ever passed over that territory. 
During the ages that elapsed from the Carboniferous to the Reaiaaees 
the Ohio river and its tributaries were excavating their valleys, and so 
also were the streams that flowed through the channel, that drained the 
northern and central part of the continent, which is now represented 
by the chain of great lakes. Where the valleys thus eroded remain 
unaffected by the drift, they are frequently immense chasms. The 
streams which flowed from the divide into the great drainage system 
of the north, cut out the valleys precisely as did the tributaries flow- 
ing south or east into the Ohio, and to equally as great depth. Could 
we see northern Ohio stripped of the drift, we would see a country 
quite as rough and rugged as southeastern Ohio. But there came a 
time when this drainage system of the north was obstructed in the 
region of Lake Ontario, and the waters were thrown back over the 
country, forming an immense lake. From this lake, deposits of clay, 
sand and gravel were precipitated over the country overflowed, and 
from the northern shore or sides of the Laurentian mountains, the shore 
ice transported to the south bowlders and rocky masses, in the same 
manner that it transports them now from one side of Lake Winnipeg 
to the other, and thus, much of the country was changed from its broken 
and hilly aspect into nearly a level plain. And when this lake over- 
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