42 J. J. Stevenson — Lower Carboniferous groups of the 



If there be any Vespertine present, it is to be found in the 

 lower part of the reddish siliceous beds. Whether or not airy 

 Vespertine exists in Tennessee cannot be determined in the 

 present state of our knowledge. It is certain, however, that 

 the group has thinned almost to nothing, if it have not wholly 

 disappeared before the Tennessee border has been reached 

 along these lines of outcrop. 



The Umbral of Pennsylvania, Maryland and the Virginias is 

 equivalent to the Chester and St. Louis groups of the Mississippi 

 Valley, and it may include the Keokuk ; while in the Vespertine 

 must be sought the equivalents of the Burlington and possibly of 

 the Kinderhook. Chester fossils are abundant in Pennsylvania 

 and the Virginias in the upper part of the limestone ; and that 

 group was recognized in 1869 b}^ Mr. F. B. Meek, during the 

 examination of some fossils collected on Cheat River near the 

 Pennsylvania line. St. Louis fossils are plentiful at man}*- 

 localities in central and southern West Virginia as well in 

 southwestern Virginia. 



The facts thus far given seem to afford basis for some con- 

 clusions respecting the geography of the Lower Carboniferous 

 periods. 



The Vespertine shore-line lay somewhere within the present 

 area of the Archaean ; the subsidence was much more rapid in 

 the northeastern part of the Appalachian gulf than it was fur- 

 ther west or southwest, the rate gradually diminishing in those 

 directions; for the 1300 or MOO feet of Huntington County, 

 Pennsylvania, becomes little more than 400 feet in Fayette 

 County of the same State, and about 800 feet in the extreme 

 southeasterly exposures within Virginia beyond New River; 

 and these are much nearer the old shore-line than are those 

 showing the great mass in southern Pennsylvania. Low or 

 marshy land reached westward for a long distance from the 

 Blue Ridge, as well as southward from the northerly shore-line 

 in New York ; for thin streaks of coal occur at several hori- 

 zons within the sandstones of Bedford County, Penn., at 50 

 miles from the Archaean, while near the New River and its 

 tributaries there are great beds in Virginia at 25 miles and, 

 according to Fontaine, in West Virginia at 50 miles, from the 

 Blue Ridge Archaean. 



The whole area under consideration was a region of shallows, 

 except perhaps the extreme southwest corner of Virginia, for 

 no limestone bed occurs except at the top where the Siliceous 

 limestone ends the column. This is first seen, and very thin, 

 on the easterly side of the Broad Top basin in Fulton and 

 Huntington Counties of Pennsylvania at 40 miles from the 

 Archaean ; whereas in Virginia it is shown equally thick within 

 12 miles of the Archaean on the northerly side of the Draper 

 Mountain fault. 



