MORGAN COUNTY. 151 



Coal Measures. This formation underlies nearly the whole surface of the 

 county, the only portion in which it is not the uppermost rock, being a com- 

 paratively limited area along the Illinois bottoms and bluffs. We find consid- 

 erable difficulty in forming a correct idea of the details of this formation in this 

 county, on account of the wide separation and varying character of the differ- 

 ent outcrops. The aggregate thickness, however, may, I think, be safely set 

 down as not less than three hundred feet, and probably still more. Within this 

 thickness there are at least three, and most probably four, beds of coal of suf- 

 ficient thickness to be profitably worked. 



The only surface outcrops of No. 1, of the Illinois river section, are along 

 the Illinois river bluffs, near the northern line of the county, in sections 2, 3 and 

 4, township 16, range 12 west of the 3d principal meridian, where it has 

 been worked to a slight extent, by drifts driven horizontally into the hillside, 

 and it has, besides, been worked at least at one point by stripping along the 

 outcrop. 



The following section, which is made up, in part, from natural exposures in 

 the northeastern quarter of section 3, and in part from information derived 

 from the parties who had worked the coal, will serve to furnish an idea of the 

 order and thicknesses of the beds at this point : 



FEET. IN. 



1. Clay shale, containing a few indeterminate, apparently vegetable, impressions, and 

 passing downwards into the underlying bed , 1 5 



2. Arenaceous shale, containing no fossils except, perhaps, a few crinoidal stems ... 3 



3. Brownish sandstone, containing a few indistinct vegetable impressions 20 



4. Black slate 2 



5. Drab, argillaceous shale (exposed) 5 



6. " " " (reported) 2 



7. Coal 2 6 



8. Fire clay, penetrated only a few inches. 



The sandstone No. 3, of this section, has been worked to some extent as a 

 building stone, and is exposed in several places along the river bluffs in this 

 vicinity. The other beds are only to be seen at one or two points, and the out- 

 crop of the coal vein itself is everywhere covered up by soil and debris from 

 the beds above. 



In the southwest quarter of section 4, township 16, range 11, it is reported 

 that a coal bed occurs a few feet belcw the bed of Indian creek, which has been 

 worked by stripping, during seasons of very low water. A little distance below 

 the point where the coal was said to occur, I observed masses of nodular, argil- 

 laceous limestone, which I judged to have been derived from the under-clay of 

 the coal. Still farther up the creek, in the northeast part of section 15, I ob- 

 served an outcrop of a reddish, concretionary sandstone, which may perhaps be 

 the equivalent of the sandstone No. 3, in the above section. 



