102 ILLINOIS ACADEMY OF SCIENCE 



streams there were no indigenous trees upon the brown 

 silt loam soil nor could any indications be discovered that 

 at any time had there been any forest upon this type of 

 soil. The characterization of the brown silt loam by the 

 members of the Soil Survey as an upland prairie soil 

 seemed thus perfectly accurate. 



On the other hand although all the bits of upland for- 

 est in the northwest portion of this county were upon the 

 yellow-gre}^ silt loam much of this soil was under cultiva- 

 tion and all trace of tree growth had disappeared. There 

 is, however, good reasons for believing that it was all 

 originally forested and hence that it may appropriately 

 bear the designation given it by the Soil Survey of "upland 

 timber soil." The evidence of former forestatiou is briefly 

 as follows: (1) A map made in 1819 purporting to show 

 the original forest areas of the county; (2) The township 

 maps showing that these areas of yellow-grey silt loam 

 were in the early surveys cut up into lots of 5 to 20 acres 

 and that these areas were held as wood lots by farmers 

 having larger farms of prairie soil elsewhere in the county ; 

 (3) The testimony of the oldest inhabitants which seems to 

 agree perfectly with soil distribution as charted; and (4) 

 The remnants of forest remaining at the time of our sur- 

 vey which were scattered over all parts of the yellow-grey 

 silt loam but were found nowhere upon the brown silt 

 loam. 



Therefore since the original distribution of upland for- 

 est in this portion of Illinois where the vegetation is pre- 

 dominatingly grassland is limited to a particular type of 

 soil bordering the streams and somewhat below the level 

 of the prairie upland, it seems fair to conclude that here, 

 at least the character of the soil is the controliug factor in 

 deciding the limits of tree growth. 



