60 LIFE OF THE PLEISTOCENE 



Stratum VI, clay. The clay deposit is believed to represent the bottom of 

 the lake during the Hammond stage. The upper part of this deposit may have 

 been a land surface during the low water period. 



Stratum VII, peaty clay. This deposit contains many shallow water mol- 

 lusks and probably represents tire Englewood stage (Nipissing stage) at its 

 highest level. 



Stratum VIII, peat. This thick bed of peat indicates a shallowing of the 

 water and records a change from flowing water to swampy conditions. At this 

 time the lake had ceased to discharge thru the Chicago outlet. 



Stratum IX , surface soil. This deposit represents the recent period when 

 the area had changed to a swamp, such as existed in the Sag region before the 

 canal was excavated. 



The interpretation indicated above may be graphically expressed in the 

 diagram on plate XXVIII, which indicates the depths of water at each stage. 3 



F. SCATTERED RECORDS 



There are a number of records of life in the museum of the Chicago Acad- 

 emy of Sciences, and in local literature, which cannot be referred to any parti- 

 cular sedimentary deposit, tho belonging undoubtedly to postglacial fossil 

 strata. These are listed below, with comments. 



Corner Wrightwood Avenue and Noilh Clark Street 

 Fusconaja undaia.* In excavation for building. In Toleston beach. 



Corner Frederick and North Clark Streets 

 Crenodouta undidata. 4 In excavation for building. In Toleston beach. 



Corner Sheffield and Lincoln Avenues 

 Goniobasis livescens 4 Pleurocera subulare 



These possibly belong to the Toleston stage. No geological data was sup- 

 plied with the specimens. 



Balmoral A venue, Bowmanville 



Goniobasis livescens. 4 This record is on the Calumet beach but should 

 probably be referred to the Toleston stage. 



Summit, bed of Sanitary Canal 

 Spkaerium sulcatum Valvata tricar inata 



Amnicola limosa Planorbis deflectus 



" lustrica " parvus 



s It is greatly to be regretted that there has been no opportunity to give to the Calumet- 

 Sag channel the careful study accorded the north shore channel. The writer was able to 

 visit the excavations of the Calumet-Sag canal but a few times, and while the information 

 secured is of value and corroberates the interpretations given to the north shore deposits, 

 it is still true that much interesting information has been lost. Science is apparently not 

 yet in position to take full advantage of the opportunities which commerce and industry so 

 often provide, frequently at great expense. 



4 Collected by Mr. Carl Dilg. 



