199 



that of the mesophytic woods on tlie lake shore spoken of above, and the 

 vegetation represents a higher type of niesophytie society. 



In the evolution of the swainp of Turkey Lake, the first vegetation is 

 of water plants. These are followed hy bulrushes or sedges, and next 

 come shrulis and trees, in some cases those noted above, but in other's 

 Cassandra calyculata which is followed by the tamarack (Larix Ameri- 

 cana). These swamps are destined to become forests, while in the case 

 of the lake like Lake Calumet, near Chicago. 111., the destiny of which 



Fig. 4. ^'iew of a portion of the l)e;ich in Cherry Creek Embayment. The slope is 

 gentle, rising from the low chiinuul of the crtek on the right to over 20 feet on the left. The 

 soil is very boggy and most of the bogs are assooiateil with mineral springs. Rows of wil- 

 lows in the right center, with sycamores and oaks on left. The rich nature of the soil is 

 apparent in the heavy herbneeous vegetation. Semi-fossilized bivalve shells were found 

 liere. 



is the pniirie. the bulrttsh stage is followed by grasses. It is suggested 

 by Dr. Cowles that this difference in the tiltiniale development of the 

 swamp m;>y be due to tlie depth of the kettle and consequently the depth 

 of the lutick. the forest type being found by him to have originated from 

 deep kettles and the prairie type from shallow ones. The muck in the 

 swamps spoken of above is deep and their destiny is evidently forest, as 

 has been pointed out. but there is very little evidence of the Cassandra 

 and the Tamarack stages. There :ire a few tamarack swamps in the 



