THE CINCINNATI ICE DAM. 195 



the present gorge of the Ohio just below Cincinnati, the river 

 would at once begin the process of cutting down its new channel. 

 A waterfall of far larger proportions than Niagara must have 

 been at once developed in the lower portion of this short cut, near 

 the junction with the Great Miami, which would steadily wear 

 back toward the old channel at Cincinnati, when, if the ice had 

 not reached so far, the water level above the dam would be speed- 

 ily lowered, but only to be raised again at a later time when the 

 advancing ice reached its farthest extent and obstructed the newer 

 channel. It is altogether probable, however, that this new chan- 

 nel below Cincinnati had not been lowered to its full extent be- 

 fore the maximum advance of the ice. If this were the case the 

 final retreat of the ice across the river would leave a rocky bar- 

 rier below Cincinnati, such as to maintain the water for a while 

 at a level much higher than that maintained at the present time. 

 There are some deposits up the riyer indicating that this was the 

 case, as, for instance, some in Teazes Valley extending from the 

 Kanawha River to Huntington. By reference to the first map it 

 will be perceived that this valley is less than seven hundred feet 

 above tide, but it is covered with several feet of very fine sedi- 

 ment, distributed evenly over the bottom of the valley, which 

 must have been deposited in still water during the later stages of 

 the Glacial period. 



A glance at the first map will also show some other most inter- 

 esting problems of change in drainage systems caused by the Gla- 

 cial period which have not been adequately studied ; for example, 

 it will be noticed that a stream rising near Madison, Ind., pursues 

 a very singular course with reference to the contour lines. This 

 is the Muscatatuck River, which rises within less than a mile of 

 the Ohio River and four hundred feet above it ; but instead of 

 following the strike of the strata, as it naturally would, around 

 to Louisville, it cuts across a broad north-and-south valley of ero- 

 sion to join the East Branch of the White River, when both to- 

 gether, continuing on in a westerly course, follow a gorge several 

 hundred feet deep through the highest portion of the State till 

 they unite with the West Branch of the White River to reach the 

 Ohio through the Wabash. It is extremely difiicult to explain the 

 course of this stream, except by some such process of reasoning as 

 has been adopted with respect to the Ohio below Cincinnati. The 

 projection of the tongue of ice which extended below Madison de- 

 flected the drainage of a considerable region through a j^artially 

 formed pass across the elevated plateau to the west, while the 

 morainic deposits about the farthest extension of the ice lobe per- 

 manently obstructed the channels in that direction, so that upon 

 the withdrawal of the ice the Muscatatuck still continued to run 

 into the Ohio by way of the Wabash. 



