MAIN MORAINIC SYSTEM IN THE GRAND RIVER LOBE. 453 



some of the large streams being' iu new channels. For example, the Cuya- 

 hoga, from Kent to the bend near Akron, is in an entirely new channel, and 

 the preglacial course of the outlet of the upper Cuyahoga is not known, 

 the drift sheet being so thick as to conceal quite effectually the preglacial 

 ridges and valleys north, west, and south from Kent, and to some extent 

 east from that city. In the main, however, eastern Ohio, like northwestern 

 Pennsylvania, has not sufficient drift to conceal the main preglacial valleys 

 and ridges. In both States the channels have been filled to such an 

 extent and in such a manner as to cause the present direction of flow to be 

 frequently the reverse of the ancient, or to have otherwise changed the 

 drainage, so that much uncertainty attaches to the mapping of preglacial 

 or interglacial drainage systems. 



In the following report of well sections appear many which have 

 already been published by the Pennsylvania Greological Survey, as well 

 as those collected by the writer: 



The section of a well in the Chautauqua Valley at Jamestown, N. Y., 

 reported by Gilbert D. Harris," shows 220 feet of drift. The altitude of the 

 well mouth is 1,326 feet. A well with similar altitude at Bemis Point 

 reached a depth of 310 feet without entering rock. 



For the Conewango Valley Carll has, in his report of Warren County, 

 Pa.," a tabulated record of the amount of drive pipe used in 42 wells along 

 the valley from the State line southward to Warren. From this table it 

 appears that the drift ranges in thickness from 50 to 270 feet. Fifteen of 

 the 42 wells pass through over 100 feet of drift and 24 pass through 90 feet 

 or more. It is Carll's opinion that the wells which show a relatively small 

 amount of drift are not in the deep part of the ancient chaimel. They are 

 all, however, in the, valley bottom, the range in altitude of the well mouth 

 being from 1,188 feet in Wan-en to 1,240 feet at the State line, with no 

 wells between whose mouths are more than 20 feet above the level of the 

 one at the State line. The valley floor shows a range from 964 to 1,162 

 feet above tide. The character of the drift is reported only for the well at 

 the State line, where it consists of blue clay to a depth of 245 feet, below 

 which is 25 feet of gravel and clay. 



In the valley of Jacksons Pun, near Chandlers Valley, a well sunk by 



1 Am. Geologist, March, 1891. 



^ Second Geol. Survey Pennsylvania, Kept. I^, p, 309. 



