164 J. J. STEVENSON CARBONIFEKOUS OF APPALACHIAN BASIN 



The Bed beds- retained their importance apparently to the end within 

 the half dozen interior counties of West Virginia and Ohio, and twice 

 during the Monongahela the area showed a very considerable expansion, 

 though in neither case equaling that of the Washington or lower reds 

 of the Conemaugh and in each very much less than that of Pittsburg 

 reds of the same formation. After the deposition of the Uniontown coal 

 bed their area diminished, and during the Washington and Greene the 

 reds became less and less important, appearing at last in, for the most 

 part, thin and rather widely separated deposits, though occasionally, as 

 in Marshall of West Virginia and northern Greene of Pennsylvania, they 

 attain considerable local importance. 



In reviewing the conditions within the north central part of the basin, 

 one is led to believe that the loss by erosion is much less than has been, 

 supposed. From the crest of Chestnut ridge, in Fayette county of 

 Pennsylvania, the whole of the Carboniferous has been removed and the 

 Chemung rocks are exposed at several places along the summit; but 

 within 5 milles toward the west the section reaches almost to the top of 

 the Washington formation, while at 20 miles farther, beyond the broad 

 valley of the Monongahela river, one finds the highest beds of the 

 Greene. It seems wholly probable that the Gilmore sandstone is but a 

 few hundred feet below the last deposit made in the Appalachian basin. 



Notes on the Palhontology oe the Pennsylvania 



the fauna 



Comparatively little attention has been paid to the Pennsylvania fauna. 

 When the early surveys were made, fossils were to most geologists little 

 more than interesting curiosities ; during prosecution of the later surveys, 

 the urgent necessity for prompt determination of mineral resources left 

 little time for collecting fossils, which indeed seemed hardly necessary, 

 as the fossiliferous horizons are comparatively few and the forms ob- 

 served in them appeared to be identical for the most part with those 

 described in the Illinois and other volumes published by western states. 

 It results that for comparison one has only the partial lists given by 

 Messrs Meek, Whitfield, White, and Stevenson.* The forms thus far re- 

 ported, with their horizons, are: 



• F. B. Meek : Kept. Regents of West Virginia University for 1870, pp. 66-73 ; Rept 

 progress of Geological Survey of Ohio for 1870, p. 79 ; Palaeontology of Ohio, vol. 11, 

 p. 326. 



R. P. Whitfield : Palaeontology of Ohio, vol. vl, p. 482. 



I. C. White : Second Geological Survey of Pennsylvania, Q, p. 62 ; Q Q, p. 46, 61 ; 

 Q Q Q, p. 25. 



J. J. Steveason : Trans. Am. Phil. Soc, vol. xv, pp. 22, 28 ; Second GeologlcAl 

 Survey of Pennsylvania, K K K, p. 309 ; Geology of Ohio, vol. ill, pp. 207, 222. 



