GLACIAL WATERS IN THE LAKE ERIE BASIN 



67 



by the invasion of a new body of water, but as far east as Manila 

 it was produced by the lowering of Lake Whittlesey or other waters. 



e The complex Warren shore lies on a plain of slight incline and 

 low relief which was the silted and fdled lake bottom of the preceding 

 Whittlesey, while the earlier and simple Whittlesey lies on the higher 

 and steeper slope. From State Line to Silver Creek the land slope 

 is uniform with no very heavy deltas or detrital fillings, and the 

 Warren bars are close set and parallel. On the plains between Silver 

 Creek and Hamburg, flat and silted, the bars are scattered. From 

 Hamburg to Alden the bars are multiple but strong and compact. 

 The divergence of the bars at West Alden into two sets seems to 

 be an accident of the topography and the tributary ice border 

 drainage. From Crittenden eastward the shore has more sim- 

 plicity, as stated above. 



/ Multiple bars are regarded as the characteristic product of 

 long-continued work of waves and shore currents in waters of 

 comparatively steady or slowly falling level, and are consequently 

 found in greater development along older and maturer shores. 

 It is uncertain to what extent submerged bars can form in water 

 which has very changeable or rising level, but such conditions are 

 believed to be unfavorable. 



g The depth of effective wave action in fresh waters has not been 

 determined precisely, but it has been regarded as not over 30 feet. 

 Supposing the Warren bars to represent a single level, the table 

 of vertical spacing would indicate that the depth of bar construction 

 could not commonly exceed 25 feet. 



h A young outlet of insufficient capacity might involve consider- 

 able fluctuation of lake level b}' the damming of high waters. This 

 would apply much more to Whittlesey than to Warren, because the 

 Warren outlet had been previously the ultimate outlet (from Lake 

 Saginaw) during all the life of Whittlesey. 



With the above facts and principles before us we will now discuss 

 the suggested explanations for the lower Warren bars. 



1 The multiple Warren bars could not have been the product of 

 lowering waters during the extinguishment of the lake or they 

 would not be so uniformly limited to the belt covered by 70 feet 

 under the Whittlesey plane, since the waters fell through the entire 

 vertical distance to the present Erie. The bar phenomena which 

 actually were produced by the subsiding or hypo-Warren waters 

 are described below and we find that they are scattering and rela- 

 tively few. Even those of the Dana level are disappointing, 

 though generally recognizable. 



