48 W. M. Fontaine — Vespertine Strata of Virginia. 



black when fresh, but weathering brown. This last contains 

 the small coal bed at the entrance to Lewis Tunnel, and has 

 afforded all the plant impressions found there. The coal is 

 quite local, and has been found nowhere else so far as I know. 

 This horizon however, in other places, often yields abundant 

 plant impressions. 



At the top we have some alternations of dark shales, with 

 olive, and reddish marlites for thirty feet, and finally red 

 marlites. No limestone was seen above the red marlites. The 

 - here indicate a quieter deposition of sediment than 

 that which took place near Greenbrier Eiver, for there the firm 

 gray flags are succeeded abruptly by the marlites. The upper- 

 most coal bed here exposed is, at its thickest, about twelve 

 inches, but soon passes into shale. 



We find from the above data that in this section the Vesper- 

 tine strata may be divided into three members. 



1. A lower member, characterized bv siliceous sandstones 

 and conglomerates. Thickness exposed,"sixty feet. With this 

 should probably be counted 500 feet of underlying, more 

 argillaceous flags, giving a total of 560 feet. 



2. A middle member, characterized bv the predominance of 

 gray sandstones containing coal. Thickness, about 850 feet. 



3. An upper member, consisting almost entirelv of red 

 marlites, and having a thickness of about 250 feet. This would 

 give the entire group a thickness of 1,1(50 feet. 



It will be seen that, as the base of the lower member is 

 ii'."/. ere exposed in this region, sixty feet cannot be taken as 

 its entire thickness. I am of the opinion that it is considerably 

 greater. Professor Eogers, in his descriptions of the Vesper- 

 tine, nowhere gives any descriptive section of the strata, so that 

 we are left in doubt as to what stratum he assumes as its base. 

 It is plain that he does not include the red overlying strata in 

 it ; this makes it difficult to use his measurements" as a basis 

 for comparison. He gives the thickness on the Potomac near 

 Westernport, as only 200 feet, while near Lewisburg he says it 

 has increased to 800 feet. This seems in any events. 

 the fact of a considerable thickening to the south. 

 [To be continued.] 



