50 J. J. STEVENSON — CARBONIFEROUS OF APPALACHIAN BASIN 



Feet 



Homewood sandstone 80 



Mercer shales and coal bed 20 to 30 



Connoquenessing sandstone 50 



Sharon shales and coal bed. . 5 to 15 



Sharon sandstone 25 



The Homewood is slightly pebbly, but the Connoquenessing is mark- 

 edly so. Usually the pebbles are not larger than a pea, though occa- 

 sionally one of egg-size occurs.* 



Stevenson studied the southern portion of the field where the section is 



Feet. Inches 



Sandstone 121 



Coal bed 2 to 10 



Shale 18 



Coal bed 2 



Sandstone 125 



in all, 265 feet, corrected to 250 feet. The upper sandstone is not con- 

 glomerate, though portions are very coarse. It contains an irregular 

 coaly streak in the upper portion, which may be equivalent to the Mercer, 

 and so at the horizon of bed A of the Northern field. The shales between 

 the sandstones with the thin coal streaks appear to represent the Camp- 

 bells Ledge horizon of the Northern field, the Sharon of northwestern 

 Pennsylvania. In the bottom sandstone of the section one must recog- 

 nize the thickened sandstone of the Campbells Ledge region, which is 

 evidently thickening southward or southeastward, being only 25 feet at 

 Doctor White's locality. It is very coarse in the upper 20 feet, which 

 contains much carbonized wood and at times rests on 5 feet of shale, 

 containing some coaly matter ; but this shale occurs only in pockets. 

 These measurements indicate that the Pottsville is thicker on the east 

 and south sides than on the northerly sides. The change is abrupt, for 

 the field is barely 7 miles wide and 20 miles long.f 



EASTERN EDGE OF : ALLEGHENY PLATEAU 



Returning now to the north to follow the edge of the Allegheny plateau, 

 one finds some isolated coal areas — the Mehoopany in Wyoming and the 

 Bernice in Sullivan county. The distance from the former to the near- 

 est point in the Northern field is approximately 25 miles. In 1883 

 Doctor White called attention to the coal area in western Wyoming, 

 which he identified with the Pottsville. The coal bed underlies a mass- 

 ive conglomerate and rests on dark shales containing abundance of plant 



* I. C. White : Geology of Huntingdon County (T3), 1885, p. 70. 



f J. J. Stevenson : Geology of Bedford and Fulton Counties (T2), 1882, pp. 65, 259. 



