442 THE ILLINOIS GLACIAL LOBE. 



not improbable that the amount of filling is such as to necessitate the 

 assumption of an even greater emergence in that region. 



The simplest conception of the lake history would postulate only one 

 period of emergence, but the available data suggest greater complication. 

 It remains to be determined whether the deep channeling may not pertain 

 to a later interval of emergence in which there was greater uplift than in 

 the interval under consideration. Observations made by the writer in the 

 vicinity of Holland, Michigan, lead to the view that the channeling occurred 

 subsequent to the formation of the strong beach which stands 60 to 65 feet 

 above Lake Michigan, and prior to the formation of a beach which stands 

 about 25 feet above the lake. If the 60-foot beach proves to be a contin- 

 uation of the Calumet or Second beach of Lake Chicago, this emergence 

 would seem to have occurred between the formation of the Second and Third 

 beaches; but if it represents the Grlenwood beach, the emergence may have 

 been in the interval under discussion. This would throw it into the same 

 category with the peaty deposits noted near the south end of the lake. 

 The lake charts indicate that the lower courses of tributaries on the west 

 side of Lake Michigan are not characterized by the deep channels which 

 are common on the east side of the lake. This may be attributable in part 

 to their being in a more elevated part of the lake border, in which chan- 

 neling was so narrow that it has been completely filled. The absence of 

 deep channels at the south end of the lake may be due to obliteration by 

 sand accumulations. It seems very doubtful if one shore suffered much 

 greater uplift than the other. Further light is necessary to a satisfactory 

 interpretation of the evidence of a low lake level. The relation of the 

 Third beach to these deep river channels on the east side of Lake Michigan 

 is set forth on a later page, as are also evidences favoring the view that 

 channeling occurred subsequent to the formation of the Second beach. 



THE SECOND OR CALUMET BEACH. 



This beach throughout much of its course in Indiana follows the south 

 border of Calumet River, and because of this close association the name 

 Calumet seems appropriate. From Chicago around to St. Joseph, Michigan, 

 it stands about 20 feet lower than the upper beach, but it may be separated 

 somewhat more widely from that beach farther north. An interval of about 

 35 feet is found between the upper limits of wave action east of Holland, 



