THE TOPOGRAPHY AND HYDROGRAPHY OF ILLINOIS li 



the underlying rocks at many points. The country near the river 

 is hilly and much broken, the valleys of the streams having been 

 excavated to a depth of 100 to 200 feet below the general level of the 

 uplands. 



Throughout its course Apple creek is a swiftly flowing stream. 

 In the first 11 miles of its course it drops 100 feet. For the rest of 

 the distance the fall averages about 5 feet to the mile. 



MACOUPIN CREEK 



Macoupin creek rises in northern Montgomery county and flows 

 southwest into the Illinois. It drains an area of nearly 1,000 square 

 miles (Leverett), consisting of the greater portion of Macoupin 

 county and parts of Montgomery, Greene, and Jersey counties. Its 

 watershed is broad in the middle and tapers toward either end, giv- 

 ing it a broadly ovate outline. The whole of the 1 >asin lies within the 

 Illinoisan drift area. With the exception of the headwater portion, 

 above Carlinville, the main stream apparently has its course deter- 

 mined by a preglacial line, there being a broad depression, deeply 

 filled with drift, through which the creek takes its course. The trib- 

 utary streams appear to be largely independent of preglacial lines. 



The basin is composed of gently rolling or nearly level prairies, 

 which occupy the highlands between the streams and cover fully 

 one third of the area, and by heavy belts of timber which skirt the 

 streams. The soil is of a black, peaty character on the level prairies, 

 becomes chocolate-brown on the more rolling surfaces, and degen- 

 erates into a light ash-gray near the streams. 



The creek is about 80 miles long. Its fall is varied, some parts, as 

 the lower 1 7 miles, having a fall of only one and one half feet to the 

 mile, and other parts much more, as the four and one half miles just 

 above this, the fall in this distance being 30 feet. Above this point the 

 average fall is about 2 feet to the mile. The banks are high, in some 

 places rising to 100 feet. In a few places the banks recede from the 

 water's edge, leaving bottom-lands one half to one and one half miles 

 in width. 



Kaskaskia River System 



The Kaskaskia River system drains a large part of southern Illi- 

 nois, its drainage basin covering an area of 5,786 square miles. It is 

 about 180 miles long, the narrow upper end reaching within 40 miles 

 of the state of Indiana. The upper third of the basin lies in Wiscon- 

 sin drift, and the other two thirds in the Illinoisan. The basin is 

 composed of level or undulating country having black soil in the 

 northern part and chocolate to light gray soil in the southern, under- 



