COBEELATIVES OF BLOOMINGTON MORAINIC SYSTEM. 119 



be traced to an Ohio River terrace that stands approximately 100 feet above the bed of the river 

 at the place where it is joined by the Whitewater gravel plain. The streams at the north ends 

 are incised but little in the gravel plains, and they therefore descend about 100 feet more than 

 the glacial streams in reaching the Ohio. Before the Whitewater had been filled with glacial 

 gravel its bed was much lower than at present, as is well shown by borings at and near Brookville 

 which enter rock 100 to 120 feet below the present stream. The valleys of the Whitewater 

 system were probably filled in large part by earlier moraines than that under discussion, but it is 

 quite likely that they received important additions of gravel and sand from it throughout their 

 whole length. 



EAST WHITE- RIVER BASIN. 



Westward a few miles from the Whitewater system is the head of the great gravel plain 

 which is followed by East White (Blue) River. Its northern end is among the morainic ridges 

 of southeastern Delaware County, whence a complex network of channels leads out to form the 

 gravel plain. Prairie Creek has a channel one-fourth nfile or less wide with a surface 20 feet or 

 more below border tracts. The tributary channels west of it near the head of Bell and Fall 

 creeks are shallower, but many of them have as great width. The valleys or marshy tracts west 

 of New Burlington are also one-eighth to one-fourth mile wide, but they have no definite banks 

 like the tributaries of Prairie Creek and probably have a greater filling with silt. The whole of 

 the Delaware County portion of these channels and the portions within 2 or 3 miles south of 

 the Henry-Delaware county line were apparently either extended northward on the with- 

 drawal of the ice or were formed beneath the ice. Where East White (Blue) River enters this 

 channel it emerges from the moraine and from this point southward has a much greater size 

 than any of the channels formed within the moraine, being nearly one-half mile wade and 40 to 60 

 feet deep. This greater size does not seem attributable to the accession of the modern stream, 

 but was probably produced by glacial drainage. Throughout Hemy, Rush, and Hancock coun- 

 ties the channel is cut deeply into the till tract, but a small part of its bluffs being less than 50 

 feet and most of them being 60 to 80 feet higher than the broad plain in which the river flows. 

 There is a terrace along this channel, but much of it was removed apparently by the glacial stream, 

 for the channel which emerges from the moraine and which was abandoned with the cessation of 

 glacial floods has a bed which traced southward forms the lower plain along the small stream 

 that now occupies it. The terraces are in all probability the remnants of a gravel-filled channel 

 which was filled by outwash either from an earlier moraine or from the early part of this moraine. 

 The waters that escaped from the margin of the ice as the morainic system approached completion 

 removed a portion of the gravel fillings from the northern part of the channel. In northern 

 Shelby County the terrace descends more rapidly than the lower plain, so that it becomes merged 

 in or buried beneath the later-formed valley drift. The glacial river channel gradually widens 

 from north to south, being one-half mile wide at its emergence from the moraine, a mile or 

 more at the line of Henry and Rush counties, and fully 1J miles at the line of Hancock and 

 Shelby counties. In Shelby County its width is still greater, but its depth is less, the 

 bordering uplands standing only 15 to 20 feet above the gravel plain. In thi.s county the 

 river has cut a channel in the gravel plain which is very small compared with the glacial flood 

 plain. In southern Shelby County it has cut a valley 15 to 20 feet deep and about one-eighth 

 mile wide in the broad gravel plain. The stream gradually deepens its valley southward, so 

 that at Columbus in Bartholomew County its bed is 30 to 35 feet and its flood plain 25 feet or 

 more below the gravel plain. Features in Shelby and Bartholomew counties have already 

 been described (pp. 70, 77). 



The thickness of the gravel in the gravel plain in Shelby County has been ascertained by 

 Mr. David Louden, a well driller residing at Shelby ville, to be 20 to 25 feet at most places and 

 to exceed 40 feet at few. The amount of excavation is, therefore, a channel 40 to 50 feet deep, 

 and this channel has been more than half filled with gravel.. 



In the upper portion of the East White (Blue) River valley no accurate sections were 

 obtained of wells in the middle of the vallej-. On the border' of the plain at Carthage and 



