228 ILLINOIS ACADEMY OF SCIENCE 



they were similar to those studied, where the conditions 

 were the same. 



A map of the area was made, built up from the topo- 

 graphic map of the Evanston quadrangle and from the 

 maps of the various towns included. Owing to admit- 

 ted discrepancies in the topographic sheet and to the 

 lack of a definite scale of miles in the city maps, certain 

 defects are known to occur in the resulting map, even 

 extending so far as to the possible location of some of 

 the section lines. The map is, however, as nearly cor- 

 rect as it was possible to make it and its value is not 

 seriously impaired. 



The larger forest areas were located on this map and 

 the position of individual forest trees noted. A more 

 intensive study was then made of the typical areas in 

 which the natural vegetation was least disturbed, or of 

 those which appeared unusual. The chief points con- 

 sidered were the composition of the forest area, both 

 in trees and undergrowth, and its general topographic 

 position, the nature of the soil, drainage conditions, 

 light, exposure and any other factors which might de- 

 termine that composition. From the results of these in- 

 vestigations and from any other information available, 

 conclusions were drawn as to the probable extent of the 

 original forests before their destruction. 



Several difficulties were encountered in making this 

 investigation, one being the possible error in deciding 

 which trees should be considered members of the orig- 

 inal forest. All oaks, hickories, and butternuts and such 

 elms, maples, ashes, lindens, cherries, birches and cedars 

 as by their size, apparent age, and location indicate 

 their presence naturally, were noted as forest trees. Mr. 

 Currey (6) however, in the "Plan of Evanston", states 

 that many of the trees of Evanston were planted by the 

 early settlers, being imported from the ''Big Woods" 

 two or three miles west for that purpose. If such is the 

 case, there may be some errors in determining the limit 

 of the original forest, but as most of these trees were 

 elms and maples which are not used as absolute criteria, 

 the results should not be far from correct. 



