76 LIFE OF THE PLEISTOCENE 



waters were discharging eastward past Syracuse, the volume of discharge at 

 Chicago was largely diminished and the lake stood slightly lower. " 



Goldthwait 23 has recorded a forest bed (containing peat, sticks, logs, and 

 tree trunks, some of the latter still standing) at Two Creeks, Manitowoc 

 County, Wisconsin, which is covered by 12 feet of stony red till. This is 

 evidently a part of a moraine laid down during a readvance of the ice. The 

 correlation of this forest bed, in time, with the Bowmanville deposits seems 

 probable (See Chapter IV under Wisconsin for a discussion of this deposit). 

 The old forest bed and the red clay are widely distributed in the Green Bay 

 Valley, showing that this period was widespread, and the episode must have 

 been of a duration sufficient for the growth of an extensive forest. 



Recent studies in southeastern Wisconsin carried on by Alden 24 suggest that 

 the Bowmanville low water stage might have occurred during the Glenwood 

 stage. The red till of the Whitehall-Port Huron moraine, near Milwaukee, 

 covers the sands and gravels of the Glenwood beach (see Alden's figure 18, page 

 311) showing that this moraine covered the high beach north of Milwaukee. 

 South of Milwaukee this beach is continuous and vigorous but "north of this 

 place there was an early Glenwood stage, then a stage of glaciation followed by 

 a later Glenwood stage " (p. 311). It would not be impossible for the Bowman- 

 ville low water stage to have occurred between these two Glenwood stages 

 especially if an outlet was uncovered somewhere to the north which has been 

 elevated since by differential uplift. The life of the Bowmanville stage is 

 such as would be likely to be found in the cold waters of a lake in which a 

 glacier was several hundred miles away. The low water stage might,. there- 

 fore, have been inter-Glenwood instead of post-Glenwood and pre-Calumet. 

 In this case there would be good evidence for a sudden drop from the Glenwood 

 level to the Calumet level of the lake. 



Whatever may have been the cause of the low water stage, its existence 

 seems beyond question and its place between the Glenwood and Calumet 

 beaches is attested by excavations in many places. It is also possible that 

 before the low water period the Chicago outlet had been cut down sufficiently 

 to lower the level of the lake to 40 feet above the present level, as the sub- 

 sequent stage did not rise above the Calumet beach which is at this height. 

 As the level of the lake during the low water stage was about ten feet above 

 datum, the Chicago outlet could not be used and the outlet river formed a long 

 narrow bay. If any deposits were made at this time they were subsequently 

 removed by the water cutting down the outlet. No deposits have been 

 observed in the outlet channels which can be referred to this stage with con- 

 fidence. The rising of the water which inaugurated the Calumet period again 



23 Abandoned Shore Lines of Wisconsin, p. 61; Lawson, Bull. Wis. Nat. Hist. Soc, II, 

 p. 170; Alden, The Delavan Lobe. 



24 Professional Paper 106, U. S. G. S., pp. 134, 311, 327, 1918. 



