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A SURVEY OF THE HURON RIVER VALLEY. 



I. THE ECOLOGY OF A GLACIAL LAKE. 



Howard S, Reed. 



(with four figures) 

 i. introduction. 



In the vicinity of Ann Arbor, Mich., there are a number of 

 glacial lakes and ponds which at no very distant day must dis- 

 appear if the processes now in operation continue. At present 

 they exhibit conditions of such interest that it has seemed very 

 desirable to preserve as complete a record as possible of their 

 extent, physical characters, and biological relations as they exist 

 today. The work here reported was carried on at the largest of 

 the so-called ** Sister lakes" west of Ann Arbor.^ It was under- 

 taken at the suggestion of Professor V. M. Spalding, of the Uni- 

 versity of Michigan, under whose direction the botanical survey 

 of which it forms a part is now in progress. It has been the 

 purpose of the writer to give an exact representation of existing 

 facts and conditions, and to study in a somewhat quantitative 

 manner the relative value of the several ecological processes at 



work; necessarily some matters of theoretical interest are dis- 

 cussed. 



The study of a glacial lake is of peculiar interest to students 

 of ecology. The physiography of the country in which such 

 lakes occur was entirely rejuvenated by the glacial action, and 

 the physiographic processes taking place now are precisely those 

 rapid developments characteristic of new land areas. Adapta- 

 tions to past conditions still remain, but with them are striking 

 and interesting adaptations to present changing conditions. The 

 general change has been from semi-arctic and hydrophytic to 

 temperate and mesophytic conditions. At the same time, there 



J A preliminary report of this work was published in the Proceedings of the 

 Michigan Acadenay of Science for 1901. 



1902] 



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