96 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY, [Dec. 20, 



§ I. lNTK0DTJCT10i;r. 



In several former papers presented to this Society, I have endea- 

 voured to illustrate the arrangement of the Carboniferous rocks of 

 Nova Scotia, and to direct attention to their organic remains, the 

 structures found in their coals, and the evidence which they afford 

 as to the mode of accumulation of that mineral. The present paper 

 is intended as the summing up and completion of these researches, 

 with the addition of the new facts resulting from a careful study of 

 the microscopic structure of more than seventy beds of coal occurring 

 in the South- Joggins section, and of the fossil plants associated with 

 them. These results will, I hope, throw much additional light 

 on some of the more difficult problems connected with the theory of 

 the accumulation of vegetable matter in the Carboniferous period, 

 and its conversion' into coal. 



The subjects to which I propose to direct attention may be con- 

 veniently arranged under the following heads : — 



(1) General considerations relating to the physical conditions of 

 the Carboniferous period in ITova Scotia. 



(2) Details of the character and contents of the several beds of 

 coal in the Joggins section, arranged in the order of Logan's 

 Sectional List. 



(3) Eemarks on the genera of animals and plants whose remains 

 occur in the coal, and on their connexion with its accumulation. 



§ II. General Considerations relating to Physical Conditions. 



1. Physical Characters of the several Coal-formations. — The total 

 vertical thickness of the immense mass of sediment constituting the 

 Carboniferous system in Nova Scotia may be estimated from the 

 fact that Sir W. E. Logan has ascertained by actual measurement at 

 the Joggins a thickness of 14,570 feet ; and this does not include 

 the lowest member of the series, which, if developed and exposed in 

 that locality, would raise the aggregate to at least 16,000 feet. It 

 is certain, however, that the thickness is very variable, and that in 

 some districts particular members of the series are wanting, or are 

 only slenderly developed. Still the section at the Joggins is by no 

 means an exceptional one, since I have been obliged to assign to the 

 Carboniferous deposits of Pictou, on the evidence of the sections 

 exposed in that district, a thickness of about 16,000* feet ; and Mr. 

 Brown has estimated the Coal-formation of Cape Breton, exclusive of 

 the Lower Carboniferous, at 10,000 feet in thickness f. 



When fully developed, the whole Carboniferous series may be 

 arranged in the following subordinate groups or formations, the 

 limits of which are, however, in most cases not clearly defined : — 



a. The Ujpper\Coal-for'mation. — It consists of sandstones, shales, 

 and conglomerates, with a few thin beds of limestone and coal. Cala- 

 mites SucTcovii, Anmilaria galioides, Cordaites simplex, Alethopteris 

 nervosa, Pecopteris arhoresccns, Dadoxylon materiariiim, Lepidophloios 

 parvus, and Sigillaria scutellata, are among its characteristic vege- 

 table fossils. 



^- Quart. Journ. Geol. Soc. vol. i. p. 329. t ^^id- vol. vi. p. 116. 



