160 Muclge — Notes on Preglacial Drainage in Michigan. 



Probably the most natural conclusion to be derived from the 

 above facts is that a branch of the main valley has its rise 

 somewhere to the south of the Saranac. Prof. Lane's contours 

 indicate a branch valley coming in from the south along the east 

 line of Ionia and Montcalm Counties. As no deep borings 

 are known along this line, it is presumed that such branch 

 valley is simply a probability, based upon little known condi- 

 tions. It would not require a very great change in the direc- 

 tion of this supposed branch valley to bring it in line with the 

 Saranac boring. 



It is not likely that the Saranac well indicates an east and 

 west valley, because the rocks to the east rise rapidly, as shown 

 by the Ionia wells and the sandstone outcrop above mentioned, 

 while to the west in the vicinity of Grand Rapids the rock 

 surface is above the 600-foot level. Neither is it probable that 

 the valley opened to the south. The only other theory is that 

 the main valley had become so extensive in Preglacial times as 

 to include the Saranac location, but this presumes an amount 

 of base-leveling out of harmony with the general situation. It 

 may, therefore, be taken as at least fairly well settled that an 

 important branch of the drainage system, probably not inferior 

 to the eastern division, exists beneath the drift not far from the 

 line indicated. Future borings along this line in Ionia and 

 Montcalm Counties will be watched with interest. 



Grand Eapids, Mich. 



