238 ILLINOIS ACADEMY OF SCIENCE 



This transition probably was not only horizontal, but 

 vertical as well, the intermediate areas representing a 

 gradual succession toward the mesophytic oak-hickory 

 association which is apparently the temporary climax of 

 the Chicago Region. 



SUMMARY 



A survey of the present forests of the Evanston-Win- 

 netka region, which includes the ends of the Lake Chi- 

 cago beaches, shows that these are three forest associa- 

 tions found : the mesophytic upland forest, the xerophytic 

 sand ridge type and the morainic swamp forest. 



These forest association types are not in distinct areas, 

 but there is a gradual transition from one to another. 



The location of the association is dependent on the 

 character of the soil and the drainage, the mesophytic 

 forest on rich well-drained soil, the xerophytic forest 

 on sandy, with good drainage and the swamp forest on 

 the poorly drained lowland clay. Where the water stands 

 too long during the year, no forest is found. 



Conclusions are drawn as to the probable extent of 

 the original forest and it is suggested that the present 

 associations on the plain represent a succession toward 

 the mesophytic association now found only on the up- 

 land. 



LITERATURE CITATIONS 



1. Atwell, C. B. 



"The Forests of Evanston, Old and New." 

 Evanston News Index, April 2, 1910. 



2. Atwood, W. and Goldthwait, J. W. 



"Physical Geography of the Evanston-Waukegan Region." 

 Illinois State Geological Survey, No. 7, 1908. 



3. Bannister, H. N. 



Cook County, in Geology of Illinois, pp. 239-256. 

 Geol. Survey of Illinois, vol. Ill (1868). 



4. Childs, Mary Louise. 



Chicago and Vicinity in 1850. 



Northwestern University, A History 1855-1905 (1905) by 

 Arthur Wilde. 



5. Cowles, W. C. 



The Plant Societies of Chicago and Vicinity. 



Geographic Society of Chicago, Bull. No. 2, 1901. 



