202 GEOLOGY OF ILLINOIS. 



Economical Geology* 



Under this head we have to consider coal, potter's clay, brick, building stone, 

 lime, hydraulic lime, iron ore and water. 



Coal, as already stated, underlies fully three-fourths of the county, the seam 

 averaging about three feet, except on the borders of the field. It is very large- 

 ly worked in the immediate neighborhood of Morris, by from twenty-five to 

 thirty shafts twice as many are now deserted varying from thirty to sixty 

 feet in depth, and several extensive " strippings." Some of these strippings 

 uncover coal thirty inches thick, which is about the average thickness in this 

 neighborhood; while others, on the borders of the outcrop, find not more than 

 eighteen inches. West of Nettle creek timber, no shafts have been opened, 

 though the seam cannot be anywhere, on this side of the river, more than 

 eighty feet below the level of the canal, and in most places much less than that. 

 A well on Gen. Birney's place, four miles west of Morris, stopped, at. a depth 

 of thirty feet, in soft, blue clay shales, apparently only a few feet above the 

 coal. 



A smaller cluster of shafts and strippings is found to the south and west 

 of Goose lake, with the average thickness of full thirty inches. At a stripping 

 in the southwest corner of section 12, town 33 north, range 8 east, the bed is 

 locally thickened to over four feet, but contains, near its center, a heavy band 

 of crystalline carbonate of iron and lime, with much disseminated pyrite. The 

 coal covers the bottom of the south half of Goose lake. 



This seam is also worked at Braceville, (section 25, town. 32 north, range 8 

 east,) by a shaft ninety-eight feet deep, and in section 26 of the same town- 

 ship, by a shaft of one hundred and ten feet. At Gardner, (section 4, town. 31 

 north, range 8 east,) it is worked by a shaft one hundred and sixty feet deep. 

 In the southeast corner of this township, three or four shafts, of about sixty 

 feet each, work this seam in its usual condition ; but one, in the northeast cor- 

 ner of section 25, finds a roof of black, slaty shale, with heavy iron-stone con- 

 cretions covering about three feet of a very pure "block coal," with much min- 

 eral charcoal in the partings. Both the coal and the accompanying beds, at the 

 mine on AuSahle creek, closely resemble the conditions found here ; and at both 

 points I have been unable to decide whether they represent a local change of 

 the main seam, or are portions of a lower seam which is only occasionally pre- 

 sent. 1 at present favor the former view. 



The upper seams, which have been worked upon the Waupecan creek, and 

 upon the Mazon, near the mouth of Johnny run, apparently occur over only 

 small areas at either locality; and elsewhere, whenever met with, they have 

 proved to be irregular seams, locally quite thick, but often running out to a mere 

 streak of coaly matter, and even disappearing altogether. It is probable that 



