THE PREGLACIAL DRAINAGE OF OHIO. 41 



and that was northwest towards Alpha. In any other direction 

 a wall of limestone is encountered. The territory between Spring 

 Valley and Alpha was once the margin of a great ice sheet and 

 when this receded it left a morainic deposit which not only pre- 

 vented the northward flow of the stream but entirely obscured 

 the old channel. From Alpha its course is plainer, because 

 from that place an old valley a mile wide in places can be readily 

 followed northwest by Osborn where it is crossed by the Mad 

 river, and thence on past New Carlisle to the Great Miami at 

 Tippecanoe. The lower part of this old valley is occupied by 

 a small stream, Beaver Creek, which is insignificant when com- 

 pared to the valley through which it flows. The other end of 

 the valley is occupied by Honey Creek, likewise a stream which 

 grossly misfits its valley. 



At two points only was the depth of drift in this old valley 

 learned. At Osborn there are 207 feet and at New Carlisle 300 

 feet. Nowhere in the valley was bed rock seen. From these 

 relations it appears not unreasonable to conclude that the old 

 stream which has been traced to Spring Valley continued north- 

 west past Alpha, Osborn and New Carlisle, and reached the 

 valley of the present Great Miami near Tippecanoe. The 

 stream could not have continued north far in this valley, how- 

 ever, for between Troy and Piqua the river flows in a very shal- 

 low channel on a bed of limestone. Neither could it have 

 continued west of the Great Miami because there a solid wall 

 of rock is found. To the suggestion that the stream may 

 have turned south at Tippecanoe and flowed through the present 

 valley of the Great Miami there is the objection that the Great 

 Miami itself is regarded by some as a reversed stream. There 

 appears then only one course for it to have taken, that is north 

 along the east side of the Great Miami to just above Piqua 

 where there is a great expansion of the valley and where the 

 drift is more than 124 feet deep. But the old river could not 

 have followed this valley far, because it contracts rapidly and 

 a few miles up stream flows over rock again. About two miles 

 north of Piqua there unites with the Miami, Laramie Creek, a 

 sluggish stream that drains Laramie reservoir situated a few 

 miles to the northwest. This stream everywhere flows over a 



