OUTWASH OF ILLINOIAN AGE. 285 



In the Whitewater Valley several boiings for gas have been made out- 

 side the limits of the Wisconsin ice invasion. They fall within the limits 

 of a terrace of Wisconsin gravel, but as the Wisconsin gravel probably 

 extends little, if any, below river level a large part of the material is thought 

 to be Illinoian. A boring at the brickyard in the south part of Brookville 

 shows the rock floor to be about 180 feet below the low- water level of the 

 stream, or but 440 feet above tide. Three other borings in the valley near 

 Brookville enter rock at a level about 125 feet below the river, or 495 feet 

 above tide. A gas boring near Cedargrove, also in this valley, penetrates 

 154 feet of drift and enters rock at about 450 feet above tide. At the mouth 

 of the I'iver the rock floor is less than 400 feet above tide 



SBCTIOK III. CHARACTER OF THE OUTWASH. 



GENERAL STATEMENT. 



In the western part of the region, from near Louisville, Ky., eastward 

 to near Maysville, the ice sheet at its culmination occupied the Ohio 

 Valley so completely that drainage must have been greatly obstructed. 

 As indicated above, the deposits appear to have been very uneven; parts 

 of the valleys apparently received but little drift, while other parts were 

 filled to a height of 160 to 200 feet above the present stream. The filling 

 is also variable, being in places a fine silt, in other places an ordinary till, in 

 other places assorted sand and gravel, and in still other places a conglom- 

 erate with a large number of coarse stones in a matrix of clay or fine sand. 

 In some of the valleys in central Ohio a terrace composed of well-assorted 

 sand and gravel appears, which is probably of Illinoian age. Reference 

 has already been made (p. 102) to the teirace in the Scioto Valley. This 

 and similar terraces in valleys farther east will now be considered. The 

 discussion begins with a terrace in Sandy Creek Valley, that being the east- 

 ernmost valley in which there appears to be good evidence of an outwash 

 of Illinoian age. Valleys to the west are then taken up in succession. 



SANDY CREEK VALLEY. 



About 1 mile east of Minerva, Ohio, Sandy Creek, a tributary of Tus- 

 carawas River, leaves the Wisconsin drift and enters what appears to be 

 an unglaciated tract. For several miles below the limits of the Wisconsin 

 drift it seems to have only one terrace above the flood plain, and this 

 is in all probability of Wisconsin age. Near Waynesburg, Ohio, a higher 



