THE LIFE OF GLACIAL LAKE CHICAGO 



71 



mette on the north to a point between the Little Calumet and the Grand Calu- 

 met rivers on the south. It extended on the east into southwestern Michigan. 

 A small bay must have developed from Foster to Devon avenues, which was 

 protected from the rough waters of the lake by a long bar. A suggested outline 

 of Wilmette Bay is shown in plate XXXIV. 



3lack sand 

 9 



Sand-qravel 

 85 



Qrai sand IS 

 Peat-wood 3, 



QRA*U-6*N0S5 



Clay 14 



Bouio'ER. 

 CLA1 



244 



'"^ "o 



w, 





a 



a§ 





m 



mm 



Calumet 35-40 



.Bo-~«««»l"E 10 HUD WHAtt 



\ Clen^ooo 5S-60 



LEVEC a.FLAKE MlCHICAN 



Figure'l. Diagram illustrating position of shallow water and land deposits beneath 

 sand and gravel of Calumet beach. Section of beach ridge south of Gross Point. Figures 

 to left of column indicate thickness of strata (inches). Figures to right of column indicate 

 depth of water (feet) of Lake Chicago at time deposit was made. 



a. Life of Wilmette Bay 



The life of this stage is characteristic of ponds and lakes, where the water 

 varies from two to ten feet in depth. The life also indicates comparatively 

 quiet waters, free from violent wave action. It is possible that bars, reefs, 

 and spits were formed to the eastward and later destroyed by the rising of the 

 water. The species of plants and mollusks contained in this deposit are tabu- 

 lated below: 



Plants 

 Quercus species Picea canadensis 



Populus balsamifera Larix laricina 



Abies balsamifera Carex sp. 



Thuja occidentalis 



Animals 

 Anodonla grandis Amnicola emarginata 



" grandis footiana " limosa 



Propter a alata " luslrica 



