Appalachian area in Pennsylvania and the Virginias. 41 



Umbral. 



Shales... 370' 



Limestones and calcareous shales 226' 



Vespertine. 

 Sandstones with siliceous limestone on top 681' 



But the writer found the Umbral shales absent from Rich 

 Mountain in Randolph County, of West Virginia, where the 

 Coal Measures rest directly on the limestone, which is more 

 than 700 feet thick, inclusive of calcareous shale. A thin 

 streak of coal occurs in the calcareous shales here opposite 

 Beverly. 



All parts of the Lower Carboniferous increase greatly within 

 a short distance southward from this locality, for in Pocahontas 

 County, of West Virginia, Prof. J. B. Rogers obtained the fol- 

 lowing measurement of Umbral on Greenbrier Mountain:* 



Sandstones and shales. 1260' 



Limestones and shales . 822' 



Red shales 50' 



2132' 



while the Vespertine is not far from 800 feet thick. The 

 maximum thickness is attained here, for near New River, ac- 

 cording to Prof. W. M. Fontaine's measurements^ the un- 

 doubted Vespertine, to the top of the coal-bearing series, is 

 barely 500 feet. The writer found the shales and sandstones of 

 the Umbral about 900 feet thick at 15 or 20 miles beyond New 

 River in West Virginia, where they show a few streaks of im- 

 pure limestone. Thence the many exposures amid the Clinch 

 faults in Tazewell, Russell and Scott Counties, as well as those 

 under the Stone Mountain anticlinal in Wise and Lee Counties 

 of Virginia, show a constant decrease of Vespertine while the 

 Umbral retains its importance, though with reduced thickness. 

 The last examined exposure is in Pennington's gap through 

 Stone Mountain in Lee County, where the section is : 



Shales, sandstones and thin limestones 705' 



Limestone and calcareous shale 150' 



Cherty limestone and siliceous beds . 200' 



Reddish siliceous beds 150' 



1205' 



* Report on Geology of Virginia for 1 839, p. 32. The absence of details makes 

 it impossible to determine whether or not the Siliceous limestone is included in the 

 Umbral, Formation XL 



fThis Journal, Jan., 1877. 



