72 Geological Society : — 



the terms are regularly positive, or alternately positive and negative. 

 But according to the view here taken, series of the former kind ap- 

 pear as singularities of the general case of divergent series proceeding 

 according to powers of an imaginary variable, as indeterminate forms 

 in j)assing through which a discontinuity of analytical expression 

 takes place, analogous to a change of sign of a radical. 



A communication was likewise made by the Rev. W. T. Kingsley, 

 " On the application of Photography to Wood Engraving." 



GEOLOGICAL SOCIETY. 



[Continued from vol. xv. p. 553.]. 



April 28, 1858. — Professor Phillips, President, in the Chair. 



The following communications were read : — 



1. "On the Lower Carboniferous Coal-measures of British Ame- 

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



Deposits indicating the e.xistence of the Coal-flora and its asso- 

 ciated freshwater fauna at the beginning of the Carboniferous period 

 are well developed in Nova Scotia and New Brunswick, with a clear- 

 ness and fulness of detail capable of throwing much light on the 

 dawn of the terrestrial conditions of the Coal-period, and on the re- 

 lations of these lower beds to the true coal-measures. This lower 

 series comprises shales and sandstones (destitute of marine remains, 

 but containing fossil plants, fishes, entomostraca, worm-tracks, 

 ripple- and rain-marks, sun-cracks, reptilian footprints, and erect 

 trees) and great overlying marine limestones and gypsums. These 

 are distinct from the true coal-measures by their position, mineral 

 character, and fossil remains. In the western part of Nova Scotia 

 (Horton, Windsor, &c.) the true (or Upper and Middle) coal-mea- 

 sures are not developed ; and here the Lower Carboniferous marine 

 deposits attain their greatest thickness. The lower coal-measures 

 (or Lower Carboniferous freshwater or estuarine deposits) have here 

 a thickness of about 600 feet. These beds are traceable as far as 

 the Shubenacadie and Stewiacke P.ivers. They outcrop also on the 

 south side of the Cobequid Mountains, where the marine portion is 

 very thin, owing perhaps to the fact of these mountains having 

 been land in the coal-period. 



Along the northern side of the Cobequid Range the upper and 

 middle coal-measures and the marine portion of the Lower Carboni- 

 ferous series are of great thickness. The freshwater beds are absent 

 here, though brought up on the northern side of the coal-trough of 

 Cumberland, where, as well as in New Brunswick (Petitcodiac 

 River, &c.), they are remarkable for their highly bituminous com- 

 position, their well-preserved fish-remains, and the almost entire 

 absence of plants. 'Jo the north, at the Bay of Clialeurs, the great 

 calcareous conglomerate, with sandstone and shale, 2766 feet thick, 

 described by Logan, and containing a few plant-remains, probably 

 represent the Lower Coal-measures of Nova Scotia. In eastern 

 Nova Scotia and Cape Bieton the Middle Coal-measures are found 



