100 PEOCEEBINGS OF THE GEOLOGICAL SOCIETY. [DeC. 20, 



America. On the whole, however, it is apparent that certain grand 

 features of similarity can be traced in the distribution of the Carbo- 

 niferous rocks throughout the northern hemisphere. 



It is further to be observed that in Nova Scotia and New Bruns- 

 wick, as well as in Eastern Canada, disturbances occurred at the 

 close of the Devonian period which have caused the Carboniferous 

 rocks to lie unconformably on those of the former ; and that in 

 like manner the Carboniferous period was followed by similar dis- 

 turbances, which have thrown the Carboniferous beds into synclinal 

 and anticlinal bends, often very abrupt, before the deposition of the 

 Triassic Red Sandstones. These disturbances were of a different cha- 

 racter from the oscillations of level which occurred within the Carbo- 

 niferous period. They were accompanied by volcanic actfon, and 

 were most intense along certain lines, and especially near the junc- 

 tion of the Carboniferous with the older formations. 



I have noticed an apparent case of unconformabiHty between 

 members of the Carboniferous system near Antigonish*. In the 

 county of Pictou the arrangement of the beds suggests a possible 

 unconformability of the Upper Coal-formation and the Coal-mea- 

 sures f. In New Brunswick Prof. Bailey j has observed indications 

 of local unconformability of the Coal-formation with the ' Lower 

 Carboniferous. But the strict conformability of all the members of 

 the Carboniferous series in the great majority of cases, shows that 

 these instances of unconformability are exceptional. In the section 

 at the Joggins, more especially, the whole series presents a regular 

 dip, diminishing gradually from the margin to the middle line of the 

 trough, where the beds become horizontal. 



The most gradual and uniform oscillations of level must, however, 

 be accompanied with irregularities of deposition and local denuda- 

 tion ; and phenomena of this kind are abundantly manifest in the 

 Carboniferous strata of Nova Scotia. I have described in ' Acadian 

 Geology' a bed in the Pictou coal-field which seems to be an ancient 

 shingie-beach, extending across a bay or indentation in the coast-line 

 of the Carboniferous period§. At the Joggins many instances occur of 

 the sudden running out and cutting off of beds ||, and Mr. Brown has 

 figured a number of instances of this kind in the Coal-formation of 

 Sydney^. They are of such a character as to indicate the cutting 

 action of tidal or fluviatile currents on the muddy or sandy bottom of 

 shallow water. In some instances the layers of sand and drift- 

 plants filling such cuts suggest the idea of tidal channels in an 

 estuary filled with matter carried down by river-inundations. Even 

 the beds of coal are by no means uniform when traced for consider- 

 able distances. The beds which have been mined at Pictou "and the 

 Joggins show material differences in quality and associations ; and 

 small beds may be observed to change in a remarkable manner, in 



* Quart. Journ. Geol. Soc. vol. i. p. 32. 

 t Ibid. vol. X. p. 42 ; Acadian Geology, p. 249. 

 \ Heport on Geology of Southern j^Tew Brunswick, p. US. 

 § Quart. Journ. Geol. Soc. vol. x. p. 45. || Ihid. vol. x. p. 12. 



•[[ Ibid. vol. vi. p. 125 et seq. 



