482 STEVENSON— THE FORMATION OF COAL BEDS. [Nov. r. 



county, West \'irginia, passed through two beds, lOO and 60 feet 

 thick, but in another well, only a short distance away, the same inter- 

 vals show 60 and 20 feet of red. Greater contrasts appear elsewhere, 

 for thick deposits of red in one well are replaced with sandstone in. 

 another, less than one eighth of a mile distant. 



The story is the same for the Greene. In southwestern Penn- 

 sylvania deposits, 50 to 90 feet thick, were seen, but they are local, 

 being absent in sections four or five miles away. There are certainly 

 some reds in the formation within the West Virginia panhandle, but 

 the exposures do not admit of measurement. Sonie important 

 deposits are reported farther south along the Ohio River Init for the 

 most part little information exists respecting them. The Greene 

 formation in West Virginia contains nothing of economic worth and, 

 with the exception of one persistent limestone, there are no definite 

 horizons. There seems to be only a monotonous succession of shales 

 and soft sandstones, all ill-exposed. But, in riding across the Central 

 area, one recognizes at once that red shale forms no insignificant 

 portion of the mass, though the imperfect exposures suggest that the 

 deposits must be lenticular like those in the earlier formations. 



Red shales are found in other coal basins and in later formations. 

 Dawson^" found them abundant in all divisions of the Coal Measures 

 from the Millstone grit to the top and with the same features as in 

 the Pennsylvanian of the Appalachian basin ; gray and red shales 

 alternate vertically and at times are continuous laterally. Conditions 

 are the same in later times ; lenticular deposits of red clays occur in 

 the glacial till of Canada and of Scotland. The great Pampean for- 

 mation as originally described by Darwin"^ would seem to be a con- 

 tinuous deposit of reds covering an area almost equal to that of 

 France ; but it varies in composition as reds do elsewhere, for records 

 of borings near Buenos Ayres show that the section consists of sand, 

 clay and green shale. Church, to whose studies reference will be 

 made on a later page, found that a vast area of the Plata region is 

 covered with reddish-yellow, semiplastic argillaceous earth, contain- 



""J. W. Dawson, "Acadian Geology." pp. 156-176. 



*' C. Darwin, "Journal of Researches," New York. 1846. Vol. I., pp. 161. 

 164, "165; "Thickness of the Pampean Formation near Buenos Ayres," 

 Quart. Joiirii. Gcol Sac, Vol. XIX., 1863, pp. 68-70. 



