92 ILLINOIS STATE ACADEMY OF SCIENCE 



FOREST CONDITIONS IN ALEXANDER 



COUNTY, ILLINOIS 



R. B. Miller, State Forester, 



AND 



Geo. D. Fuller, University of Chicago 



introduction 



Among the reasons for selecting a portion of Alexander 

 County to exemplify the forest conditions of southern Illinois 

 accessibility is the most important. The Mobile and Ohio 

 railroad traverses the eastern side of the county and the 

 Illinois Central and Missouri Pacific the western edge. The 

 fact that the northern portion has been topographically sur- 

 veyed and mapped in the Jonesboro quadrangle and that a 

 soil survey of the area has been made, although the results 

 have not been published, made a forest survey more practi- 

 cable. A further reason for its study is that both the "Ozark 

 upland," or hill country, and the alluvial flood plain are well 

 represented. The area included in this preliminary survey 

 is limited to that part of the county included in the Jones- 

 boro quadrangle and extends six miles southward from 

 Union County and 15 miles eastward of the Mississippi, and 

 includes about 82 square miles. Two-thirds of this is up- 

 land and the remainder in the flood plains of the Mississ- 

 ippi and Cache rivers. These plains range in elevation from 

 332 to 344 feet, while the hills reach an elevation of 800 feet 

 above mean sea level at two or three points. 



GEOLOGY 



The eastern and more elevated portion of the area under 

 consideration is immediately underlaid by rocks of Devon- 

 ian age. The most recent are those referred by Savage (1) 

 to the Early Mississippian and named by him Springville 

 Shales. These and the underlying Devonian shales are 

 known locally as "Calico Rocks" and are thus designated by 

 Worthen (2) in an early account of the geology of the 

 county. They are mostly gray to greenish rocks which on 

 weathering become variegated and mottled in various shades 

 of brown and red. In places in the vicinity of Elco these 

 shales have become strongly silicified and are worked as 



