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The entire forest area of the state is classed with the Central 

 Hardwood Forest. There are, however, some general differences in 

 forest conditions between northern and southern Illinois. The dividinsf 

 line may best be taken as the south limits of the middle Illinoisan and 

 early Wisconsin glaciations, and may be roughly indicated as a line 

 from St. Louis to Shelbyville and thence east to the northeast corner of 

 Clark County. South of this line the country was once largely 

 forested, with but comparatively little prairie, while to the north 

 the original forest was for the most part confined to belts following 

 the principal drainage lines. Typical southern species, such as overcup, 

 cow, and swamp Spanish oaks, tulip-tree, cucumber, red gum, tupelo, 

 and cypress, are wanting in northern Illinois. Here the northern 

 hardwoods take the place of these, but the variety of species is not so 

 great. The southern part of the state also contains a larger proportion 

 of absolute forest land, that is, land which is better adapted to timber 

 production than to agriculture. 



Forests of Southern Illinois 

 SOIL areas and forest types 



The southern Illinois region includes a variety of physiographic 

 conditions. The largest division is the lower Illinoisan glaciation, 

 which extends from the northern limits of the region to the ungla- 

 ciated highlands which begin near the south border of Jackson, 

 Williamson, Saline, and Gallatin counties. This country is level or 

 undulating, and drained by rather sluggish streams meandering in 

 broad flood-plains. Except where it is broken by bottomlands along 

 the Kaskaskia, Little Wabash, and other rivers, the soil is a thin 

 loess deposit underlaid by a clay subsoil. The corresponding forest 

 type is termed the upland plain type, and is characterized by slower 

 growth and less variety of species than the other types of the region. 



Along the Mississippi River bluffs is a fringe of broken country 

 covered with a deep loess deposit, described as a yellow fine sandy 

 loam. The unglaciated area is also a rugged, hilly country, being an 

 extension of the Ozark plateau. Here the soil is chiefly a yellow 

 silt loam. The soil and subsoil are more porous than in the lower 

 Illinoisan glaciation, and consequently more favorable to tree growth. 

 Although there are some minor differences, the forests of the Missis- 

 sippi bluffs and the Ozark highlands are classed together as the upland 

 hill type. It includes a greater variety of species than any other 

 upland type of the state. 



The entire hill region is bounded on three sides by the bottom- 

 lands of the Mississippi, Ohio, and Wabash rivers, while it is broken 



