1847.] LYELL ON THE COAL-FIELD OF EASTERN VIRGINIA. 261 



1. On the Structure and Probable Age of the Coal-Field of the 

 James River, near Richmond, Virginia. By Charles Lyell, 

 Esq., V.P.G.S. 



Contents : — Geological structure of the Coal-fieldy p. 261 . — Vertical 

 Catamites, ip. 262. — Thickness of Coal, p. 263. — Sections, p. 264. 

 — Organic structure and mineral composition of the Coal, p. 268. 

 — Analyses, p. 269. — Beds of Coal altered by Trap, p. 270. — 

 Natural Coke, p. 272. — Position of Trap, p. 273. — Age of the 

 Coal as determined by organic remains, p. 274. — Shells, p. 274. — 

 Fossil fish, p. 275. — Whether the strata are of freshivater ori- 

 gin, p. 278. — Fossil plants, p. 278. — The Coal-measures probably 

 of the age of the Inferior Oolite and Lias, p. 279. 



Geological Structure of the Coal-field. 

 There are two regions in the state of Virginia (a country about 

 equal in area to the whole of England proper) in which productive 

 coal-measures occur. In one of these, which may be called the 

 Western Coal-field, the strata belong to the ancient carboniferous 

 group, characterized by fossil plants of the same genera, and to a 

 great extent the same species, as those found in the ancient coal- 

 measures of Europe. These strata form an integral part of the 

 system of rocks constituting the Appalachian chain, and have been 

 disturbed by the same movements, and subsequently exposed to the 

 same denuding action. Another coal-field, wholly disconnected from 

 the above in its geographical and geological relations, is found to the 

 east of the Appalachian mountains, in the middle of that granitic 

 region sometimes called the Atlantic Slope. This district of granite, 

 gneiss, hornblende, schist, and other hypogene rocks, intervenes be- 

 tween the palaeozoic rocks of the AUeghanies and the low country 

 bordering the Atlantic, which is composed of cretaceous and tertiary 

 deposits. In consequence of the isolated position of these eastern 

 coal-beds, the lowest of which rest immediately on the fundamental 

 granite, while the uppermost are not covered by any overlying fos- 

 siliferous formations, we have scarcely any means of determining 

 their relative age, except by the characters of their included or- 

 ganic remains. The study of these induced Prof. W. B. Rogers, in 

 his memoir published in 1842 (Trans, of American Geologists, 

 p. 298), to declare his opinion that this coal was of newer date 

 than that of the Appalachians, and was about the age of the oolite, 

 a conclusion which, after a careful examination of the evidence on 

 the spot, and of all the organic remains which I could collect, appears 

 to me to come very near the truth. The only doubt that can be 

 entertained on the subject in the present state of our knowledge is, 

 whether we should refer the strata to the triassic or oolitic period ; 

 and if we incline with Prof. W. B. Rogers to the latter opinion, 

 these rocks must then be considered as the only ones hitherto known 

 in all Canada and the United States, which have been proved by 

 their organic remains to be of contemporaneous origin with the oolitic 

 or Jurassic formation of Europe. 



