OF DENISON UNIVERSITY. 59 



This preglacial Muskingum drainage received a tributary 

 from the south along the hne of the lower postglacial Muskin- 

 gum gorge comprising probably the waters of the Little Kanah- 

 wa region or possibly the latter may have continued up the 

 valley of the Hocking. 



Another tributary entered from the south along the lower 

 Scioto, a continuation of the Big Sandy. The present Ohio ap- 

 propriated a part of this stream from the point of the Ohio at 

 South Point to Portsmouth. Possibly another tributary en- 

 tered from the Miami region made up from the present Licking 

 of Kentucky and a small stream represented in position by a 

 part of the Ohio above Cincinnati or possibly this drainage set 

 farther to the west and did not enter the preglacial Muskingum. 

 How much further down the Ohio this plan of northern drain- 

 age can be applied is not known. The upper eastern Mississippi 

 basin then before the ice invasion consisted of a great river sys- 

 tem with its axis corresponding in general with the axis of Lakes 

 Erie and Ontario. It received a great tributary from the south, 

 the preglacial Muskingum and one from the north through Lake 

 Huron. Both of which would form a gradually converging sys- 

 tem to the axial valley. 



If we were to speculate on the action of the ice sheet in 

 reconstructing this preglacial drainage into that of the present, 

 in a few words it would be about as follows. The great lobes 

 of the glacier conformed largely to the great axes of drainage, 

 one along the axis of Lake Huron, another along that of Lake 

 Erie. As the latter advanced with its load of drilt which it was 

 continuously depositing in front of itself it filled up its own 

 drainage line with the accumulations represented in^Indiana, and 

 also blocked the outlet of the preglacial Muskingum so that the 

 waters were backed up until they crossed a col to the south in 

 the vicinty of Cincinnati or possibly at Hamilton. Finally a 

 great arm of ice extended south into the Miami and Scioto lobes 

 which produced respectively the great St. Paris accumulation 

 west of the Mad river Urbana basin and the other the drift wall 



