202 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and vegetable structure have been obliterated, and where the litho 

 logical character of the accompanying sedimentary rocks has been 

 entirely altered. I may remark that the Silurian and Devonian 

 formations, which are so largely developed in the United States, 

 yield no beds of coal or anthracite which could by metamorphosis 

 be supposed to become turned into such a carbonaceous stratum as 

 that of Worcester. 



I shall conclude by observing that the difference of strike be- 

 tween the mica- schist containing plumbago at Worcester, and the 

 nearest carboniferous rocks of Rhode Island and Massachusetts, 

 affords no argument against the theory of both having belonged 

 originally to the same group of sedimentary strata. In New 

 England, and in Nova Scotia, the coal-measures frequently deviate 

 widely from the same strike in continuous districts, and the direc- 

 tion of continuous anticlinal axes in the Alleghany mountains, 

 composed throughout of similar silurian and carboniferous rocks, 

 has been shown by Professors W. B. and H. D. Rogers, to vary 

 more than 40° in different sections of that chain. 



Appendix. — Analysis of Specimens of Bituminous and Anthra- 

 citic Coal of the United States, and of the Plumbaginous 

 Anthracite alluded to in the foregoing Paper. 



In the Transactions of the Association of American Geologists, 

 1840-42, p. 470., Professor H. D. Rogers traces the gradation in 

 the proportion of volatile matter m the coal, as we cross the Appa- 

 lachian basin from the S. E. towards the N. W. In the most 

 southeasterly basins, where the coal is a genuine anthracite, he 

 states that the quantity of gaseous matter, chiefly hydrogen, varies 

 from 6 to 14 per cent., as, for example, in the anthracite coal 

 fields of Pennsylvania. 



Secondly, further towards the N. W., in the Alleghany moun- 

 tain of Pennsylvania, and the Potomac basin and others in Virginia, 

 the proportion of volatile matter varies from 16 to 22 per cent. 



Thirdly, westward of the Appalachian mountains, in the wide 

 coal-field watered by the Ohio river and its tributary, the amount 

 of volatile matter is from 30 to 40, and even 50 per cent. With 

 a view of testing these results, I submitted to my friend Dr. J. 

 Percy, of Birmingham, for examination, specimens of coal, first, 

 from the Pennsylvanian anthracite of Lehigh and Mauch Chunk, 

 in which the proportion of gaseous matter, (hydrogen, oxygen, and 

 nitrogen) proved to be about 5 per cent. ; secondly, from Frost- 

 burgh in Maryland, a part of the Appalachian mountains further 

 west, where the strata have only undergone a moderate degree of 

 disturbance. In this coal, the proportion of volatile matter to the 

 carbon and ash was found to be about 9^ per cent. ; and, thirdly, in 

 the horizontal and bituminous coal of Pomeroy, on the Ohio, the pro- 

 portion of gaseous matter was determined to be about 19 per cent. 



