HISTORICAL REVIEW 17 



Illinois, a considerable number of small shells was collected by the writer, which 

 confirm the earlier observations of Marcy, Alden, and others, that the Toleston 

 beaches show abundant signs of life. The shells are all of existing fresh-water 

 types. As no such fossils have been discovered in the 40 to 60-foot beaches of 

 Lake Chicago, it is inferred that the 24-foot stage was one whose waters were 

 not frigid, as in Lake Chicago, but in which the Chicago district was much 

 more remote from the ice, as was the case in Lake Algonquin. Shells of similar 

 species, but of larger size, were also found in April, 1906, in beach ridges of the 

 Algonquin group (18 feet above the lake) at Huronia beach, near Port Huron; 

 and they have been collected from the Algonquin beach in other parts of eastern 

 Michigan, by C. A. Davis and other members of the Michigan Geological 

 Survey." 



The species of shells from the beach at Evanston, as identified by Mr. 

 Bryant Walker, are as follows: 



Valvata tricarinata . Planorbis parvus 



Amnicola limosa Pisidium (3 species) 



1908. goldthwait. 27 — Life during the Calumet stage is suggested by 

 Goldthwait, who says (page 63), "Near Beach station the Calumet ridge ap- 

 pears on the brink of the Toleston bluff, and runs northward with short inter- 

 ruptions to the State line, never far from the bluff of the lower stage. Through 

 Zion City it is followed by Elizabeth Avenue. Near Winthrop Harbor it was 

 cut away, during the Toleston stage, for half a mile. Although usually a low, 

 faint feature, and subdued by ploughing, it is broad and strong between Zion 

 City and the Camp Logan road. Here a peaty deposit, lying between the 

 Glenwood and the Calumet beach ridges, contains a great abundance of fresh 

 water shells. 



"Since these shells are all of living species and none have been found either 

 here or elsewhere within stratified deposits of the Calumet beach, they seem 

 not to belong to Calumet time, but rather to the present. There are no certain 

 traces of life in the lake during the Glenwood and Calumet stages. " 



The molluscan species, as identified by Bryant Walker, are as follows: 



Galba reflexa Planorbis trivolvis 



Physa elliptica " bicarinatus 



Pisidium species " parvus 



The shell deposit cited above is, as suspected by Goldthwait, quite recent, 

 representing the bed of a swale or summer-dry pond. The writer has examined 

 many such deposits in this and other localities. 



Life during the Toleston stage is reported as abundant by Goldthwait. Of 

 the sections observed on the campus of the Northwestern University, he says 

 (page 65): "A recent cross-section in the bluff, where the ridge runs out to the 



" Bull. HI. State Geol. Surv., No. 7, 1908. 



