306 COUNTY AND REGIONAL GEOLOGY. 



popularly called the "three rivers," their separate names 

 being the North, Middle, and South rivers. The remainder is 

 drained by a few small tributaries of Raccoon river which 

 reach within its northern border, and also by an npper 

 branch of Grand river which cuts across its southwestern 

 corner. The latter stream is a tributary of the Missouri, 

 while all the others are drained into the Mississippi. It 

 will thus be seen that the watershed of these two great 

 rivers passes through the southwestern corner of this county. 



The numerous streams of Madison county, together with 

 their tributaries, make it one of the best watered counties in 

 the State; besides which, springs are numerous along the 

 valleys, and excellent water also may be obtained almost any 

 where by digging wells of moderate depth. The rapid slope 

 and rocky beds of these streams render them peculiarly 

 valuable for water-power, and a large number of costly mills 

 have already been erected upon them. 



The surface of this country may be divided into two 

 separate parts for convenience of description, each part 

 possessing its own peculiarities, which are derived from the 

 two formations that respectively underlie them. The first 

 consists of a high prairie surface with comparatively slight 

 undulations, the streams which traverse it having cut their 

 valleys down deeply and abruptly through the strata beneath; 

 the uplands ending abruptly on either side of the valleys. 

 These are the strata of the Upper coal-measures and are 

 abundantly exposed along the steep valley-sides. The 

 surface of the second part has a lower general level and is 

 usually gently undulating. The valley-sides are seldom 

 steep, and rocking bluffs are entirely wanting. This is 

 because the underlying Middle coal-measure strata contain so 

 few hard and durable layers of rock. Consequently, they 

 present no bold fronts where the streams in deepening their 

 valleys, have cut through them. 



The cause of this difference in the character of the surface, 

 it will thus be seen, arises from the difference in the resistance 

 which the two formations have respectively presented to 



