SAWYER — CLIMATIC CHANGE IX ILLINOIS. 255 



mian (Dyas) does not exist in Nebraska ; which does not prevent 

 them, however, from coloring a part of their geological map, 

 accompanying their reports, as having a Permian (Dyas) belt 

 across the State of Nebraska from the Kansas boundary line to 

 the River Platte ! 



On Climatic Chansce in Illinois — its Cause. 

 By Amos Sawyer. 



The object I have in view in directing your attention to this 

 subject, is not to defend some pet theoiy of my own, but in order 

 that older heads than mine ma\' be induced to investigate it, and 

 determine as to the correctness of my views. 



The great change which has taken place in our climate has, as 

 a natural consequence, excited our curiosity to try and find out 

 the cause or causes producing this result. I shall, therefore, state 

 the case as witnessed by the writer in this section of Illinois, and 

 attempt to show that the reasons heretofore assigned are not in 

 themselves sufiicient to account for the change, but are untenable, 

 or at least not applicable to this part of the country. 



During the last twenty years our climate has been slowly but 

 surely changing from wet to dry ; and although this change has 

 been beneficial in a sanitary point of view, agriculturally consid- 

 ered, it has, and will hereafter prove to be, a great obstacle to the 

 successful cultivation of our soil. In trying to account for this 

 change, some writers attribute it to the destruction of the forest 

 trees ; others, to the cultivation of the soil, which they claim 

 " promotes and hastens evaporation," etc. But the most import- 

 ant agent — one that is yet to produce greater mischief — seems to 

 have escaped their attention : it is the aqueotis. The chemical 

 and mechanical effects of this a^enc}^ are constantly at work, and 

 the result is plainly visible in the deepening of the channel of all 

 our small streams. 



In the early history of our State, when the wild grass grew 

 rank, and even little ponds had watei^-basins from three to five 

 feet deep, the process of evaporation was carried on much more 

 slowly than at present, and consequently when the heat became 



