98 GEOLOGY OF ILLINOIS. 



a mile further down the creek, a tunnel has been made into the coal where it 

 was said to be five feet thick, but, from the partial filling up of the opening, 

 we were unable to ascertain its exact thickness. In the vicinity of Marietta, 

 we found a coal seam opened in 1859, on section 12, township 6 north, range 

 1 east, which we are inclined to believe is this coal, though the seam is here 

 only about two feet six inches in thickness. In the bluff, at Seaville, the 

 blue silicious limestone usually overlying this coal, is found about twenty-five 

 feet above coal No. 2, but there is only a few inches of black shale to represent 

 the coal that belongs below it. In the bed of Coal creek, three miles northwest 

 of Fairview, this coal is 'found in the bed of the creek. It is here only about 

 eighteen inches in thickness, and is overlaid by about two feet of bituminous 

 shale, above which is the blue silicious limestone about two feet thick, con- 

 taining the characteristic fossils of this coal. Nodules of septaria, associated 

 with a band of iron ore, occur here, above the limestone. This septaria, has a 

 blue ground, veined with pearl spar, and affords very handsome specimens. 



Coal No. 4 is a very persistent seam in its development, and has been found 

 at every locality in the county that we have examined, where the proper hori- 

 zon for it was exposed. On the south side of Spoon river, it underlies the 

 high lands about Astoria, and we found it opened a half mile northwest of the 

 town in 1859. The seam is here from four and a half to five feet in thick- 

 ness, and -is overlaid by two feet or more of black shale that forms a good 

 roof. Nodules of dark blue limestone occur in the black shale above the coal, 

 filled with the characteristic fossils of this horizon. On the north side of Spoon 

 river, we found this seam outcropping in the bluffs of Big creek, west of Bryant 

 Station, about twenty five feet above the creek valley. The coal had been un- 

 dermined here, in the excavation of the valley, and a portion of it. with the 

 overlying strata, and covering a considerable area, had fallen down about twenty 

 feet below its original level, and retains its horizontal position so nearly, that 

 we were at first disposed to regard it as the apparent outcrop of two distinct 

 seams, but further investigations showed that all the coal exposed here, proba- 

 bly belonged to the same horizon. The roof shales at this locality contained 

 many large concretions of bituminous limestone, filled with the characteristic 

 fossils of this seam, among which are Discina nitida, very abundant, Productus 

 muricatus, abundant, Clinopistha radiata, Schizodus curtus ? Pleurophorus solen- 

 iformis, P. radiatus, Nautilus, one or more species, and a small Orthoceras. 



This seam has been more extensively worked by Mr. David Williams, at Can- 

 ton and St. Davids, than by any other person in this county. His main shaft 

 is about half a mile southwest of Canton, and is about eighty-five feet in depth, 

 passing through the following beds : 



FEET. 



Drift clay 30 



Sandstone and shale 50 



