206 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



Stones of the Rockcastle. As the area grows smaller in ascending, it becomes 

 necessary for comparison to consider separately the lower and the upper portion 

 of the Washington. * * * The formation thus increases from i6o feet in northern 

 Washington of Pennsylvania to above 480 feet in the northern counties of West 

 Virginia, thus showing a continuance of the Monongahela conditions, with the 

 greatest subsidence in north-central West Virginia. 



"The sandstones tell the story of steadily contracting area. The Waynesburg 

 sandstone is persistent in Maryland, in most of Pennsylvania, as well as southward 

 in West Virginia for a long distance. It is massive and at times pebbly, though, 

 like all sandstones of the higher formations, it is sometimes replaced abruptly 

 by shale. In Ohio, along the northwestern border, it is not a coarse sandstone, 

 but farther south it becomes coarser and more prominent, being Professor 

 Andrews's upper sandstone and conglomerate. Thence southeastwardly along 

 the southern border, in Jackson and Putnam of West Virginia, the rock marking 

 this horizon is a coarse sandstone, with quartz pebbles sometimes an inch in 

 diameter. In the interior portion of West Virginia records of oil borings show 

 sandstone persistent in this interval, except in a small area. The Waynesburg 

 is the first sandstone of wide extent in the interior region. No notable sandstone 

 above the Waynesburg appears in Pennsylvania, except that underlying the Upper 

 Washington limestone, which is confined to the borders of the remaining area 

 and disappears southwardly. Below this one finds local sandstones, but they are 

 unimportant. In the southern portion of the basin, on the contrary, the interval 

 above the Washington coal bed is characterized by great sandstones, the Marietta 

 of Doctor White, which appear in their greatest development toward the south- 

 west outcrop, though they are prominent features across West Virginia, extending 

 northward to midway in the State. 



"The limestones of the Washington are quite as perplexing as those of the 

 Monongahela and they are confined to a smaller area. * * * The limestones of 

 the Washington bear much more resemblance to calcareous muds than do those of 

 the Monongahela, but it is difficult to discover the source whence they were derived. 

 [Mr. Stevenson is inclined to think that these limestones are not marine in origin.] 



"During the Washington the crustal movements were sluggish within the 

 basin of deposition. Thin streaks of coal extend over great areas, many of them 

 showing complex structure; but toward the close the movements became more 

 pronounced, and during the early portion of the Greene the deep portion of the 

 basin was confined to Greene County of Pennsylvania and a narrow strip adjoining 

 at the west in West Virginia. * * * 



"That the area of deposit was contracting rapidly appears also from the 

 sandstone deposits. * * * All of these [the Nineveh, Fishcreek, and Gilmore 

 sandstones] are along the middle line of the basin, where during deposition of all 

 formations prior to the Washington the sandstone intervals were usually filled 

 with shale. The sources of supply were much nearer than in earlier periods. 

 But the basin, though rapidly losing in width, still extended for not less than 200 

 miles in north-northeast to south-southwest direction when the Nineveh limestone 

 was laid down. 



"The limestones, except the Nineveh, are of little importance. * * * There 

 is no evidence that the sea actually entered the area in which rocks of the Greene 

 formation remain. 



"The Red Beds retained their importance apparently to the end within the 

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



