1902] 



SURVEY OF THE HURON RIVER VALLEY 



133 



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face of the water, the sedges begin to move out and occupy the 

 territory thus prepared for them. Perhaps at first they send out 

 a few skirmishers that occupy the top of some muskrat's mound, 

 but generally they advance with an unbroken line and cover the 

 soft muck with a tough quaking mat of vegetation. No advance 



Fig. 3. — Gravelly shore at southeastern corner of the lake; absence of Nuphar 

 and Carices results in a permanent shore-line. * 



of any extent Is ever made without a fairly firm soil to grow 

 upon. Scirpus laciistris is one of the foremost plants in the 

 advance. As the Carcx zone crowds upon the Nuphar zone, so 

 in turn it is itself crowded upon by the Salix zone. Salix rostrata 



a 



pumila 



ing upon the Carices. On gravelly banks and in localities where 

 conditions are unfavorable for the growth of Nuphar, this process 

 of filling does not occur, because the preliminary process of 

 filling by decay cannot take place. The result is that the shore 



