22 pp. REPORT OF PliOGliESS. FOJSTAIKE & WHITE. 



but two beds in the series. The most imi)ortant of these is 

 the Pittsburg, which, in some places, attains a maximum 

 thickness of 6 feet. The other coal lies above, at an un- 

 known distance. Its thickness is not known, as it seems to 

 be too unimi^ortant to have attracted any attention. The 

 comparatively small development of this series, in the 

 south, is but a continuation of that change in the conditions 

 controlling the deposition of the strata, which we find com- 

 menced in the underlying Lower Barren Measures, and 

 which we will find intensified in the succeeding Upper Bar- 

 ren Measures. This change consists in the reversal of the 

 comparative thickness of the groups in the northern and 

 southern portions of the State, and in the production of a 

 greater development to the northwards. 



In the north, we find two coal beds, separated by small 

 intervals from the Pittsburg. The lowest of these is the 

 Redstone, which occurs 25 to 40 feet above it, and the other 

 is the Sewickley, which is found 80 to 100 feet above. A 

 third coal, not so persistent in W. Va. as the two last named, 

 is found from 90 to 100 feet below the top of the series. 

 This is the Uniontown Coal, a seam which attains its max- 

 imum development in the adjoining portions of Pennsyl- 

 vania. 



The strata composing the Upper Productive Measures in 

 the northern portion of W. Virginia are limestones, often 

 quite impure, grey shales, and argillaceous thinly bedded 

 sandstones. The entire mass indicates the dex^osition of 

 sediment in pretty deep water, during a widespread sub- 

 mergence which removed the shore lines to a considerable 

 distance. Indeed the prevalence of fine sediment Avhich 

 marked the subsidence following the formation of the 

 Mahoning Sandstone in the Lower Barren Measures, holds 

 throughout the entire interval up to the Waynesburg Sand- 

 stone, and seems not to have been affected by the elevation 

 of the surface which gave rise to the formation of the Pitts- 

 burg Coal. The great amount of limestone found in the 

 interval between the Pittsburg Coal and the Waynesburg 

 indicates a very considerable subsidence of the Appalachian 

 Region where such a mass of limestone is found. This 



