OUTWASH FROM THE MIAMI LOBE. 335 



Miami, in a course singularly out of harmon}- with the present svstena of 

 drainage, its course being directly across Mackocheek, Long, Buck, and 

 Beaver creeks. It connects with the Little Miami Valley east of Spring- 

 field near Thorpe station and, swinging to the southwest, follows down that 

 valley. The width ranges from a half mile or less up to nearly 2 miles. 



There is a marked southward descent along this gravel belt, the alti- 

 tude above tide being near Kennard 1,185 feet, east of Urbana about 1,150 

 feet, at Catawba station 1,090 feet, at New Moorefield 1,0G0 feet, and at 

 the point of connection with the Little Miami drainage near Thorpe about 

 1,030 feet. The general elevation of this gravel belt is about 100 feet 

 above the gravel plain along the neighboring portion of Mad River Valley, 

 and, as it is distant from that valley only 3 to 6 miles, through much of its 

 coui'se within the present Mad River drainage basin, the descent toward 

 Mad River is more rapid than along the line which the old stream followed. 

 It is for this reason that the eastern tributaries of Mad River now pass 

 directly across this old line of drainage. 



The course selected by the old stream appeal's to have been just out- 

 side the Miami ice lobe at a time when Mad River Valley was buried 

 beneath the ice. The moraine which lies west of the gravel plain beai's 

 out this interpretation, for it seems to be of the same age as the gravel 

 jDlain, and knolls in places come down to the level of and merge into the 

 plain. The eastward-bearing strise near Urbana also show that the Miami 

 ice lobe extended about to this gravel plain. On the east side of this 

 plain there is a blufflike border which indicates that the drift on that side 

 was exposed for erosion and hence is probably somewhat old«r than that on 

 the west. Its freshness, however, is such as to place it within the early 

 Wisconsin glacial stage. 



The gravel plain has been eroded to a markedly greater degree by the 

 streams that cross it than the late Wisconsin terraces on the same streams. 

 It has been cut down from a level 20 or 30 feet and occasionally 50 feet 

 above the late Wisconsin terraces, while those terraces are seldom 5<) feet 

 above the present stream. There is also a broader excavation above the 

 level of the late Wisconsin terraces than below, which makes the contrast 

 still more striking. As erosion iii gravel is a comparatively sIoav process 

 under ordinary conditions, these features seem to indicate that an interval 

 of considerable length separates this gravel deposit from the late Wisconsin 

 gravels along Mad River and its tributaries. 



