BEACHES OF LAKE WHITTLESEY. 757 



CAUSE FOR THE LOWERING OF THE LAKE. 



It is probable that the lake level was lowered through the opening of 

 lower passages than the Ubly outlet, either across or around the north end 

 of the thumb of Michigan. Taylor has noted channels and scourways 

 among the morainic hills north of the Ubly outlet that seem to have afforded 

 outlets siifficiently low and capacious to have drawn down the lake level.'^ 

 As that region is now (in 1901) under investigation, the precise relations 

 will probably soon be determined. 



1 Bull. Geol. Soc. America, Vol. VIII, 1897, pp. 47-48. 



