158 Geological Society :-— 



bone-bed lying loose at the end of the lane, and containing character- 

 istic fish-remains ; but though he searched carefully, he could not find 

 in situ the bed from which it had been detached. 



December 20, 1865. — Sir Charles Lyell, Bart., in the Chair. 



The following communication was read : — 



" On the Conditions of the Deposition of Coal, more especially 

 as illustrated by the Coal- formation of Nova Scotia and New 

 Brunswick." By J. W. Dawson, LL.D., F.R.S., F.G.S. 



In several former papers Dr. Dawson has endeavoured to illustrate 

 the arrangement of the Carboniferous rocks of Nova Scotia, and to 

 direct attention to their organic remains, the structures found in the 

 coal, and the evidence which they afford as to the mode of accumu- 

 lation of that mineral. In this paper the author summed up and 

 completed his researches, adding some new facts resulting from the 

 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. 



Some general considerations relating to the physical conditions of 

 the Carboniferous period in Nova Scotia were first given, the author 

 dividing the strata representing that period into ( 1 ) the Upper Coal 

 formation, (2) the Middle Coal formation, (3) the " Millstone-grit " 

 formation, (4) the Lower Carboniferous marine formation, and (5) 

 the Lower Carboniferous Coal-measures, describing the characters of 

 these divisions in detail, and giving a sketch of the physical con- 

 ditions which prevailed during their deposition. He was of opinion 

 that we must regard each of the above-mentioned divisions as the 

 evidence of a period presenting during its whole continuance the 

 diversified conditions of land and water, with their appropriate 

 inhabitants, and as forming a geological cycle in which such con- 

 ditions were to a certain extent successive. 



As in previous publications, so in this, Dr. Dawson contended 

 that the occurrence of Stigmaria under nearly every bed of coal 

 proves beyond question that the material of the coal was accumu- 

 lated by growth in situ, while the character of the intervening strata 

 proves the abundant transport of mud and sand by water ; in other 

 words, the conditions implied are such as prevail in the swampy 

 deltas of great rivers. He also stated that the coal consists prin- 

 cipally of the flattened bark of Sigillarioid and other trees, mixed 

 with leaves of ferns, Cordaites, &c, and other herbaceous debris, 

 and that the Cannel Coal and Earthy Bitumen are of the nature of 

 the fine vegetable mud which accumulates in the ponds and shallow 

 lakes of modern swamps. 



In the succeeding portions of the paper the author gave details of 

 the character and contents of the several beds of coal in the Joggins 

 section, arranged in the order of Sir W. E. Logan's sectional list, 

 and made some remarks on the genera of animals and plants whose 

 remains occur in the coal, and on their evidence as to the mode of 

 its accumulation. 



