OUTWASH OF THE MIAMI LOBE. 375 



from the moraine. The ice sheet apparently occupied the northwestern 

 end of the valley while its waters were filling the portion of the valley 

 outside the ice with gravell)^ deposits, and withdrew without filling up the 

 portion of the valley which lay beneath it to as high a level as the glacial 

 waters had filled that outside. 



Near Springfield the present Mad River enters a narrow rock-bound 

 valle}^ for a few miles, but emerges near Snyder's station into a broad plain 

 several miles in width. The plain extends on the northwest nearly to New 

 Carlisle, where it connects with a gravel outwash or apron of the moraine. 

 Here we find jjhenomena similar to those just described in the Mosquito- 

 Nettle Creek Valley. From the outer border of the moraine there is a 

 plain descending southward to Mad River, while on the inner border is the 

 valley of Honey Creek leading northwestward to the Great Miami, the 

 highest point between the two rivers being at the junction of the moraine 

 with the gravel plain near New Carlisle. 



From the expanded portion of the gravel plain under consideration a 

 valley leads southward to the Little Miami River. It is occupied through- 

 out its entire length by Beaver Creek, the head of the creek being in the 

 Mad River gravel plain and the mouth at the Little Miami. It is much 

 smaller than Mad River Valley, its width near Byron and also near its 

 mouth being but 60 to 80 rods. This valley was probably occupied by a 

 stream at the time of the highest stages of tlie waters which formed the 

 Mad River plain, but seems on account of its small size not to have carried 

 the main stream for any gi'eat length of time. The valley may be older 

 than the Mad River gravel plain, though it was apparently somewhat 

 enlarged at the time that jjlain was occupied by glaciaF waters. 



About 4 miles west from the point where Beaver Creek Valley leaves 

 the Mad River gravel plain, the river enters the outer member of the 

 morainic system under discussion. It joins the Clreat jMiaini at Dayton, 

 and that stream passes southward along the inner border of the outer 

 member and leaves the moraine aboiit 25 miles below the point where Mad 

 River entered it, its course throughout much of that distance being about 3 

 miles back from the outer border of the moraine. This extension of the 

 ice sheet beyond the valleys of Mad and Miami rivers raises some interest- 

 ing questions. Did this bridging of the valleys by the ice sheet produce an 

 obstruction or dam sufiicieutly strong to prevent the waters of Mad River 



