GRUNDY COUNTY. 195 



nearly continuous outcrop for a mile up the stream, the last spot observed being 

 at " Hog-grove quarry," in the southwest quarter of section 28. At the road 

 crossing, about half a mile down the creek fronj the coal mine, the sandstone 

 rises a little, and exposes about six feet of blue and black shales, filled with 

 small Mollusca of the genera Pleurotomaria^ Macrocheilus, Euomphalus, Ortho- 

 ceras, Nucula, Aviculopecten, Productus, Chonetes, Hemipr-onites, etc., and yield- 

 ing some small remains of fish, such as Petrodus octidentaliz, and the type of 

 the new Crustaceon, Ceratiocdris ? sinuatiis, M. and W. The lower part of the 

 blue shale holds two thin layers of rusty brown nodules of carbonate of iron, 

 which often partially or wholly include shells of the above named Mollusca. 

 The upper part of the black shale also contains nodules of the same material, 

 (with probably some phosphate of lime,) but smaller and less evenly distribu- 

 ted ; the smaller of these contain comminuted scales and bones of fishes, and 

 judging from both form and contents, are probably the 'fossil excrement of 

 larger fishes. These beds, with others, outcrop at intervals for about a mile 

 along the right bank of the stream; and the following section will fairly repre- 

 sent the whole: 



FEET. 



1. Sandy shale 5 



2. Blue clay shale 3 



3. Fissile sandstone 15 



4. Blue clay shale, with iron nodules 4 2 to 5 



5. Black shale, top slaty, with small nodules, bottom very fragile 2 "3 



G. Cone-in-cone, locally becoming a solid limestone $ " 1 



7. Soft olive shale 1 



8. Solid gritty sandstone 1 



Another outcrop, on nearly the same horizon, occurs on Morgan creek, from 

 the center of the south line of the southwest quarter of section 6, town- 

 ship 32 north, range 8 east, to near the center of the south line of section 25, 

 township 33 north, range 7 east. The strata are here very irregular in thick- 

 ness, but the following section gives an average representation of the exposed 

 outcrop: 



FEET. IN. 



1. Ironstone conglomerate, (local.) 6 



2. Sandstone . 8 



3. Black shale, some slaty, with large ironstones 3 to 4 



4. Cone-in-cone, running into massive limestone 2 to 6 



5. Olive shales, changing into concretionary argillaceous limestone 5 " 7 



6. Soft black shale 2 " 3 



7. Blue clay shale 9 



8. Coal No. 3 ? 2 



9. White fire clay ? 



Small quantities of coal have been mined at this seam at several points 

 along the limited outcrop. The latest opening was by Mr. Herald, for his own 



