223 



Lake, Kosciusko County, Indiana. Hero the lake level has boon lowered 

 so rapidly that a meadow is developing without the usual intervening: 

 marginal swamp life. 



Fourth. — Two additional comparative notes should be added. At 

 the west end of Turkey Lake is a kettlehole which exhibits the early 

 Stages of the process. In parts the lake has been tilled to (ho surface 

 with plant remains. In some places the advance into deeper water is 

 being made along the surface, so that a shelf of plant life exists with 



Fig. 11. Kettlehole north of Eagle Lake. 



very little beneath it except vegetable debris and water. The plant 

 which contributes most to this is swamp loosestrife (Decodon verticil- 

 latus). It is soon assisted by sedges and willows, so that the zone which 

 contains Decodon only is very narrow. 



North of E'agle Lake is another kettlehole (Fig. 11), which exhibits 

 the latter part of the process. The circular flat basin filled with peat 

 and surrounded by moraines indicates clearly its origin. The water 

 content of the soil would indicate mesophytic conditions. However the 

 central part of this area is occupied by tamaracks. This affirms the prop- 

 osition of Cowles that the change in topography may outstrip the co-ordi- 

 nate modifications of plant societies. 



