98 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



while the lower portion decreases with equal rapidity, so that the whole 

 thickness, 300 feet at the southeast, becomes, in successive measure- 

 ments, 240, 102, and finally only 40 feet on the western border. South- 

 eastward from Rockcastle it shows increase in Pulaski, and thence 

 until the maximum is reached in Pine mountain of Bell and Whitely 

 counties.* 



In Laurel county, south from Jackson, the Rockcastle group is shown 

 with greatly increased thickness on a branch of the Cumberland river, 

 but no information respecting this county is available beyond the state- 

 ments that in northern Laurel, near Pittsburg, a boring found ten coal 

 beds below the Laurel (Sharon) coal bed, and another near the Cumber- 

 land river found eight, all of them belonging to this group. In Pulaski, 

 which is south from Rockcastle and west from Laurel, the rocks are 

 shown at many places, especially in the eastern half of the county. In 

 the western part Mr Lesley found the thickness, as in Rockcastle, not 

 far from 300 feet and diminishing westwardly. The upper plate is about 

 80 feet, where thickest; in the lower portion, with an extreme thickness 

 of 200 .feet, he finds five beds of coal at 27, 80-93, 125, 150, and 175 feet, 

 the last underlying the 80-foot ledge of conglomerate, a persistent coal- 

 bearing horizon from its first appearance in Clay county for a long dis- 

 tance southward. He finds these five beds present in Wayne county 

 southwest of Pulaski and extending to the Tennessee line. Clinton is 

 west from Wayne along the Tennessee line and contains the most west- 

 erly fragments of the formation. Professor Loughridge's section gives 

 the structure at a locality near the last western exposure : 



Feet 



1. Conglomerate 30 



2. Micaceous sandstone 42 



3. Coal bed and fireclay 3 to 4 



4. Shaly sandstone 140 



5. Sandstone 60 



an extreme thickness of about 275 feet and the rocks almost wholly 

 sandstone. A thin coal bed was found resting on the lowest sandstone, 

 so that here there remain the two persistent beds. The distinction 

 between Sharon sandstones and sub-Sharon shales has disappeared. It 

 is evident from the thickness of the mass that the shoreline must have 

 been turned sharply westward as it passed beyond the area of Rockcastle 

 county .f 



*Jos. Lesley: Fourth Report, pp. 480, 482. 



G. M. Sullivan : Geology of Parts of Jackson and Rockcastle Counties, 1891, pp. 7, 15, 18. 

 t Jos. Lesley : Fourth Report, pp. 484, 485, 480, 488, 490. 



R. H. Loughridge : Geology of Clinton County, 1890, pp. 24, 25. 



C. J. Norwood : Tenth Annual Report of Inspector of Mines, 1894, p. 129. 



