GRUNDY COUNT?. 199 



yards distant, it thickens to between five and six feet, and becomes quite soft. 

 This shale has yielded a few small Discinse, and Lingulse, and a few fragments 

 of fish scales ; but these are not sufficient to determine its position in the series. 

 The bed seems to be but a small outlier, covering only a few acres, as borings 

 to the southward and westward have failed to find any continuation of the bed 

 in these directions, while to the northward and eastward, the shales and lime- 

 stones of the Lower Silurian, outcrop within a few hundred yards. I am still 

 uncertain whether this is a locally peculiar condition of the main seam, or lies 

 above or below it. If it be the main seam, the black roof shales are probably 

 the equivalent of the bed mentioned in the LaSalle county section as lying 

 there about eighteen feet above the coal j but no other outcrop of it has been 

 seen in this part of Grundy, though it appears in Wilson's shaft in the south- 

 east corner of the county. 



Another peculiar outcrop, of uncertain connections, is along the Kankakee, 

 from the east line of the county to the " Head of the Illinois/' in section 36, 

 township 34 north, range 8 east, where the river has cut through some fifty 

 feet of shales and sandstones of the Coal Measures, including a thin seam of 

 coal, and has reached the underlying shaly limestone of the Cincinnati group. 

 A few indistinct plants have been met with in the sandstone, but in too poor 

 condition for specific determination. The following section was taken on the 

 west bank of the river, about midway of the length of the exposure as above 

 named: 



FEET. IN. 



1. Soil and gravel 2 



2. Boulder clay. 2 



3. Dark purplish shaly clay , 2 



4. Ferruginous shale 3 



5. Coal 10 



6. Coaly shale, with thin layers of sandstone 8 to 10 



Y. Sandstone 6 



8. Gypsiferous clay 3 



9. Olive shales 3 



10. Ash colored shales, with limestone nodules 8 



1 1. Limestone of Cincinnati group 



In other parts of the outcrop, the ash colored shales, No. 10, contain as many 

 as six distinct layers of the limestone nodules, which appear like good material 

 for making hydraulic cement. The sandstone No. 7, thickens to the south- 

 ward, aud forms at least fifteen feet of the bluff at Schoonmaker's ford, on the 

 county line, where it contains many spherical concretions, both large and small, 

 and a few indistinct Lepidodendra and Catamites. The coaly shales, No. 6, 

 become more carbonaceous in the same direction, and finally are replaced by a 

 true coal, which, with No. 5, forms a layer which is known in the neighbor- 



