1863. J Jgg [Lesley. 



Brush, and other Silurian and Devonian mountains did. There is 

 an immense nonconformable chasm in the column west of the Hudson 

 River, and the Catskill Mountains over it have no coal upon their 

 backs ; but the coal conies in regularly enough on them at the Le- 

 high, (a less distance than from Sydney to St. Peters, or from Pictou 

 to Windsor), and the nonconformability in the Upper Silurian and 

 Devonian has already disappeared. 



Professor Dawson's fourth objection would be good, if I had really 

 " supposed the coal-measures of Eastern Cape Breton to represent 

 the whole of the coal-measures of Nova Scotia." But I only sug- 

 gested that they may prove to be the equivalents of the system of j^ro- 

 ductive coal-measures ; that is all. Between the Monongahela and 

 the Ohio, our column of productive coals is capped by another of 

 barren shales and soft sandstones of unknown height, by one estimate 

 3000 feet thick ; and part of this column may represent the so-called 

 Permian measures, which, in Kansas, cap conformably the coal-mea- 

 sures. Having no knowledge of the fossils, I have no desire to oppose 

 the conclusions of Professor Dawson, as to the part of the column of 

 the Joggins to which the Glace Bay coals apply, but hope that his 

 accurate handling of them will secure some certainty about it. It 

 was the grouping of the beds, and not the fossils, which I wished to 

 bring into prominent notice j because the doctrine of isolated basins, 

 when unfounded or overapplied, is as injurious to lithological truth, 

 as the careless identification of surface aspect may at any moment 

 prove to palaeontology. I willingly leave to accomplished palaeontolo- 

 gists like Professor Dawson, the discussion of the grand generaliza- 

 tion embodied in his sixth objection ; but I may be permitted to 

 believe that it has had its birth in the doctrine of isolated basins, 

 and that the two must stand or fall together. It also seems to me 

 to involve radical inconsistencies; for if I comprehend it, it asserts, 1. 

 That the flora of the whole coal-measures (25,000 feet?) is identical; 

 that is, the vertical distribution of each and all the plants is complete 

 from the bottom to the top. 2. That nevertheless, there are differ- 

 ences observable between different coal-beds. 3. That these are attri- 

 butable rather to difference of station and conditions of preservation, 

 than to lapse of time; that is, if we could take the beds, each one in 

 its whole extent and its fossils in their original condition, there would 

 be no differences observable between different seams after all. 4. 

 That groups or assemblages of species in the Lower, Middle, and 

 Upper coal-measures may nevertheless be distinguished ; that is, while 

 each and every species may be found occasionally in all parts of the 



