Geology of Upper Illmois. 147 



and the canal, it is intended, by means of a short cut across the 

 bottoms in the direction of the dotted hnes, (v on the map,) to 

 admit boats from the river ; and thus at a trifling expense, to con- 

 vert it into a steam-boat basin. An improvement of this nature 

 will have its value greatly enhanced, arising out of the mineral re- 

 sources so remarkably accumulated at this point, the future devel- 

 opment of which is destined to confer upon Rockwell numerous 

 commercial and manufacturing advantages. 



It is within a few rods only of the eastern extremity of the Con- 

 sogin basin, that the largest out-crop of coal in the valley of the 

 Illinois occurs. By a reference to our map, a ravine will be no- 

 ticed as descending from the high prairie, at a distance of about 

 seventy rods from the eastern boundary of Rockwell. This is 

 the Swanson ravine. Its bed is entirely within the coal strata, 

 and very nearly conforms in direction to their basseting edges. 

 The slopes of the ravine consist superficially, to a considerable 

 extent, of soil and loose materials. Slight excavations however, 

 are all that is requisite to reveal the strata, which, on the west side 

 at least, are uniform and continuous up the valley. Commencing 

 at the mouth of the ravine on its western side, we have a good 

 view of the position of the coal-bed, where it has been partially 

 laid open, for supplying to some extent fuel to the vicinity, espe- 

 cially for blacksmithing purposes. The following section was ta- 

 ken at the locahty, from the top downwards: — 



50 to 60 feet of the superior slope, concealed by soil, 



4^ feet gray marly slate-clay. 



4 inches argillo-calcareous iron ore. 



8 " gray marly slate. 



1 foot 4 inches limestone, 



1 " 4 " black bituminous slate, 



2 feet gray marly slate-clay. 

 6 " coal. 



This brings the coal-stratum nearly to the bottom of the ravine, 

 in which however, a well has been sunk, thereby making us ac- 

 quainted with the strata for a depth of at least thirty feet more, 

 but showing only alternations of blue and gray slate-clays. The 

 dip of the coal and its associated layers is W. S. W. at an angle 

 between 15 and 20°. 



As the State owns the section on which this coal opening oc- 

 curs, no farther labor has been expended with a view to trace the 



