1871.] 115 [Shaler. 



been deposited in the form of swamp accumulations, and thus must 

 have been laid down upon horizontal surfaces. There is every reason 

 to suppose that the present condition and arrangement of the materials 

 in the Dismal Swamp on the eastern side of the Richmond ridge exactly 

 correspond to what was to be found in the region now occupied by the 

 coal field we are considering, at the time when the vegetable matter 

 of which it is composed was in the state of formation. Thus we have, 

 on either side of a low dividing ridge, two basins of nearly equal size 

 and comparable forms, the one holding vegetable matter, which has not 

 yet been converted to coal, the other showing us an advanced state 

 in this process of conversion. I know no other point where the pro- 

 cess and the product, of forming coal are shown so well together. 



It is evident that if we could determine with accuracy the age of 

 the beds which embrace the Richmond coal, we should thereby fix 

 the most remote time at which this mass of the disturbing ridge had 

 been uplifted. It was long ago perceived that the Richmond coal 

 was not of the same age as the more extensive beds which lie to the 

 westward. As yet the precise period to which it is to be referred is 

 not yet determined. The first determinations of a trustworthy char- 

 acter assigned a Liassic age to the fossil plants found in the coal beds. 

 Although these determinations have sometimes been called in ques- 

 tion, no naturalist has ever yet assigned a time earlier than the Trias- 

 sic period as the age when these beds were formed. Accepting these 

 determinations, and of their trustworthy character there seems no 

 occasion for doubt, we must conclude that the East Virginia uplift 

 dates sometime later than the formation of the Alleghanies, provided 

 the general opinion among geologists, which refers the elevation of 

 that chain to the close of the carboniferous period, should be accepted 

 as correct. 



This is conclusive that two axes of elevation, coinciding in eleva- 

 tion very closely, yet of different age, is not in accordance with 

 some of the views which were advanced by M. Elie de Beaumont, 

 and for many years have had a singular influence upon the minds of 

 geologists. The principal point in the theory of M. de Beaumont 

 was that all chains, elevated at the same time, stand in a parallel 

 relation to each other, even though they might be a hemisphere apart. 

 In the same connection it was held that all the elements of the same 

 chain, standing to each other in the sort of relation in which the sep- 

 erate elements of the Appalachian system stand to each other, were 

 uplifted at the same time. The extraordinary ability with which the 



