306 



Illinois .Natural History SuRviiv Bullktin 



Vol. 28. Art. 2 



visits to certain stations in an attempt to 

 obtain unusual species that had not been 

 taken on our initial visits, but that hail 

 been recorded at the stations by Thompson 

 5c Hunt. The streams sampled and the 

 number of collecting! stations on each 

 stream, including: stations for cruisinji and 

 supplemental samplin<:, were as follows: 

 Salt Fork 55, Sani^amon 39, Kaskaskia 22, 

 Embarrass 20, Middle Fork 11, and Lit- 

 tle \'ermilion 5. The distribution of these 

 152 localities is depicted in i\\i. 4. 



Sources of Additional In:orination. 

 — Se\ eral Champaiji;n County anj^lers pro- 

 vided reliable observations. The records 

 they provided were evaluated separately 

 from those of our own collections; their 

 degree of reliability is fulh' indicated in 

 the Annotated List of Fishes. Fwo opera- 

 tors of commercial fee-fishing lakes pro- 

 vided information that was used. 



DESCRIPTION OF COUNTY 



In about a century, much of Champaign 

 County has been converted from marsh- 

 land infested with deer flies to well- 

 drained, fertile farmland. It has been in- 

 tensively cultivated for several decades, 

 and its streams have been modified by 

 dredging, tiling, silting, and other in- 

 fluences that accompany agricultural prac- 

 tices. The human population has mush- 

 roomed in recent years, and some areas 

 have become industrialized, providing an 

 opportunity to observe the effects of sew- 

 age and industrial wastes on streams and 

 stream life. 



Located in east-central Illinois, Cham- 

 paign County, fig. 5, is ib miles from 

 north to south and 27 miles from east to 

 west. It occupies 988 stjuare miles (632,- 

 415 acres) of flat to slightl\ rolling land; 

 the present relief resulted from relatively 

 recent glaciation and from postglacial 

 stream erosion. The altitude ranges from 

 630 to 860 feet above sea level and aver- 

 ages about 710 feet. Although essentially 

 a flat plain, it is somewhat higher than 

 surrounding counties, and four major 

 stream systems arise within tlie county. 

 Two other stream systems originate a 

 short distance north of the county limits. 



The county has been glaciated twice, 

 but the efiects of the more recent Wis- 

 consin stage (about 18,000 years ago) ob- 

 scure those of the much older Illinoian 



stage. The series of end moraines, which 

 rise from 50 to 100 feet above the inter- 

 morainal basins, usually form boundaries 

 between drainage s\ stems. The entire 



FifS. 5. — Lf)cation of Champaign County nnd 

 i'.s streams in relation to the state and major 

 drainage systems. The dotted line indicates 

 the boundary of a particularly fertile area, at 

 one time mostly prairie marsh. 



county is overlaid with a mantle of Wis- 

 consin glacial till, which is covered with 

 a layer of loess of varying thicknesses up 

 to 8 feet, except where the loess has been 

 eroded away. The county contains no rock 

 outcrops. 



Soils 



The soils reflect the soil parent material, 

 the drainage, and the vegetational history 

 of the area. Dark upland prairie soils 

 make up about 92 per cent of the area; 

 yellow-gray silt loams, the upland timber 

 soils, make up about 5 per cent; bottom- 

 land or terrace soils constitute the small 

 remainder (Hopkins et dl. 1918:6). 



A recent arrangement of the soil types 

 of Champaign County is presented in the 



