8 LIFE OF THE PLEISTOCENE 



taken from the silts at the corner of West Monroe and Morgan streets in 

 Chicago." 



Higley and Raddin recognize a low water stage, but place it previous to 

 the formation of the Glen wood beach, whereas the evidence now at hand leads 

 to the conclusion that the low water stage followed the Glenwood beach forma- 

 tion and that the waters rose subsequently only to the Calumet beach level 

 These authors also call attention, apparently for the first time, to changes of 

 climate during the existence of Lake Chicago, as evidenced by the remains of 

 the oak and spruce. 



1895. tjpham. 14 — Mr. Upham thus writes of the organic remains contained 

 in the deposits at Evanston: "Fresh-water shells are found abundant in the 

 15-foot beach at Evanston and elsewhere southward through Chicago. All 

 species obtained, representing ten or more genera, are still living in this region. 

 Wood of oak and cedar, and the thigh of a deer, have been also found in the 

 same beach at Evanston. " The peat bed of the 15-foot beach is also recog- 

 nized by this author as having been formed before the 30-foot or middle beach. 



1897. leverett. 15 — In this paper Mr. Frank Leverett presents considerable 

 information concerning the presence of life in the deposits under discussion. 



Glenwood stage (pp. 70-71) 



Mr. Leverett discusses the gravel pit at Oak Park (Mr. Haas') and gives 

 the same section published in his previous paper (see 1888). Mr. Leverett 

 comments further on the molluscan shells. "Upon visiting the region again 

 and inquiring particularly into the circumstances, there seems little question 

 that the shell was picked up near the base of the pit by some of the workmen, 

 but it was found that there are a few Indian graves on the bar, which extend 

 down nearly to the level of the base of the pit. The shell, therefore, may have 

 been introduced at the time of burial of some brave warrior, or it may have 

 been of more recent introduction. This is apparently the only place along the 

 entire length of the upper beach where molluscan shells have been found, and 

 this negative evidence strengthens the view that the shells at this point may 

 be intrusions. Remains of terrestrial life have also been found here. Mr. 

 Haas preserved fragments of the tooth of a mammoth found in the gravel pit 

 V at a depth of several feet. These fragment are waterworn, and it seems, 

 therefore, quite probable that they were imbedded during the formation of the 

 beach. 



Post-Glenwood Low Water Stage {page 71) 



"After the Glenwood beach was formed the lake appears to have with- 

 drawn from the plain between the beach and the shore of Lake Michigan, in 

 Illinois. How much farther north it withdrew is not accurately determined. 



14 Amer. Journ. Sci., (iii), XLIX, p. 6, 1895, 23rd. An. Rep. Geol. Surv. Min. p. 168, 1895. 

 16 Bull Nat. Hist. Surv., Chi. Acad. Sci., II. 



