were wanting in this region. Forests occupied the area and open prairies 

 were the exception. 



North of this region the tight clay subsoil does not generally appear. 

 Although! most of the other glacial deposits were made subsequent to the 

 Lower lUinoisan deposits, yet in these other regions conditions favorable 

 to a sod resulted in the building up of a loan rich in organic matter, the 

 black loams of the true prairie. Tree growth here was limited to stream 

 valleys and to eroded slopes or moraines, and grassy prairies were the rule. 



Although glaciation has modified the relief throughout 93% of the 

 state, yet the three unglaciated regions, Jo Daviess county, Calhoun 

 county, and the entire southern 35 miles of the state, show a decidedly 

 broken topography. The highest and lowest points in the state are with- 

 in these regions, and the difference of relief may be 500 feet in a quarter 

 section. Rock outcrops are common, clear streams follow a steep gra- 

 dient over a rocky bed, and these regions present features quite at vari- 

 ance with the usual conception of Illinois. The soils over this unglaci- 

 ated portion are not generally deep, excepting certain areas adjoining the 

 Mississippi flood-plain where the loessial deposits occasionally attain a 

 depth of thirty feet. These unglaciated areas were heavily forested and 

 remain today the most picturesque and heavily wooded regions of the 

 state. 



The Original Forests of Illinois 



In the solitude of the forest, surrounded by venerable trees, the im- 

 pression is one of immutability as eternal as the hills. Yet change and 

 movement is written in every chapter of forest history from that distant 

 age when Mesozoic seas washed the roots of tree ferns, down to today. 

 Pine followed tree fern, broad-leaved species followed pines. Long 

 periods elapsed when soil and climatic conditions were stable, certain 

 types of tree associations developed, and held the land until some shift 

 of the earth's crust or change in the climate altered conditions and ushered 

 in a new type of forest. The obliteration might be complete, as when 

 the sea or ice came over the land, or it might be a gradual transformation. 

 Palms and figs flourished in Illinois at certain periods ; later fir and spruce 

 followed the retreating ice sheets. Broad-leaved species eventually sup- 

 planted the conifers over most of the state. These broad-leaves were 

 extending out onto the prairies when the white settler appeared, and along 

 the Wabash and Ohio River they surpassed in size the hardwoods of any 

 other region of America. 



To the pioneers the prairies were a novel feature, and it naturally 

 followed that Illinois should be called the prairie state, yet we find that 

 her forests occupied nearly as much area as her prairies, and were unusual 

 in both variety of species and sizes attained by individual trees. These 

 original forests occupied something over fifteen and a quarter million 

 acres, or 43.58 per cent of the land surface of the state. They dominated 

 the upland and bottomland throughout the southern third of the state 



