6 NOTES ON THE NORTHWEST. 



portion of Illinois known as the military bounty tract, situated 

 in the northern part of the State, is extracted from a volume 

 called ''Illinois in 1837." As it is applicable to all the valley 

 of the Upper Missisippi, with very slight variations, a very 

 accurate idea may be derived from it of the structure of any 

 portion of that country. In Iowa generally the vegetable 

 mould at the top is a little thicker than it is here stated: — 



" A scientific gentleman who has recently examined the 

 central parts of the Military Bounty Tract, has given the 

 following as the geological structure of the upland prairies 

 in that region. That the same general structure prevails 

 throughout the entire peninsula (between the Illinois and 

 Missisippi Rivers), and all the central and northern parts of 

 the State, is most probable. 1st. Vegetable mould, formed 

 by the decomposition of grass upon the original clay soil, 

 eight to thirty inches : 2d, pure yellow clay, three to eight 

 feet : 3d, gravelly clay, mixed with pebbles, four to ten feet : 

 5th, limestone rock, two to twelve feet : 5th, shale, covering 

 a stratum of bituminous coal, generally four to five feet 

 thick : 6th, soapstone ; then sandstone. The bed of lime- 

 stone seems to be universal in this region, it having been 

 discovered in all the wells that have been dug, and in all the 

 banks of water-courses of any magnitude." 



Although no part of this region can with propriety be 

 denominated hilly, yet upon the Wisconsin, Fox, the head 

 waters of Rock and Milwaukie Rivers, the country is consider- 

 ably diversified with hills, or rather swells, and valleys. The 

 only hills worthy of particular notice, not only in this vicinity, 

 but in the whole section under consideration, are the Ocooch 

 and Smoky Mountains, which are broad and elevated ridges 

 rather than mountains. The former is situated about twelve 

 miles north of the Wisconsin, one hundred miles above its 

 mouth; and the latter about forty miles south of the portage 



