t 



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1902] SURVEY OF THE HURON RIVER VALLEY 12 J 



cape extended into the lake, which now appears as a hill near its 

 southeastern corner. West and southwest of this cape the 

 water's edge was about twenty rods back of its present position, 

 and the former western margin was approximately parallel to 

 the present one, but four or five rods farther inland. A shallow 

 bay extended off toward the northwest, which is still traceable 

 by the extension of plant zones in that direction. On account 

 of the steepness of the northern shore, the water on that side 

 extended only a few rods beyond its present limit. 



This former extension of the lake has had a marked influence 

 upon the present plant societies. While it prevailed it neces- 

 sarily drowned out all terrestrial forms; then as the water level 

 slowly fell the aquatic and semi-aquatic species had the first 

 chance to get a foothold and become established upon the land 

 which was thus gradually uncovered. This was especially the 

 case on the east, west, and southwest shores of the lake, where, 

 on account of the gentle slope of the bottom, there was always 

 a wide strip of shallow water in which aquatics and semi-aqua- 

 tics could get a strong foothold and become established long 

 before it was suitable for the occupation of terrestrial forms. 

 Even today the zone of willows is destitute of any considerable 

 number of distinctly terrestrial plants. 



At a certain stage in the recent geological history of the 

 region, as the water level fell, the large lake was divided into 

 two, the present lake and a similar, smaller one ten rods south of 

 it which has all but disappeared. The fate of this smaller lake 

 throws some light on the history of the present lake, as will be 

 shown later. 



III. PRESENT CONDITIOxNS. 



I- Physiographic relations. — As it now exists, the extreme 

 east and west diameter of the lake is a little more than thirteen 

 hundred feet long, the extreme north and south diameter is 

 seven hundred feet. Between the water's edge and the higher 

 ground which formerly constituted the shores is a swampy 

 border varying in width from ten feet to twenty rods. The 

 thick growth of vegetation in this border has nearly clogged the 



