COMPAKISON WITH THE PENNSYLVANIA, ETC. 145 



says (2). But I confess to a complete scepticism of the great extent 

 which has been assigned to this unconformability of the coal measures 

 upon the lower rocks; first, because most of the Island of Cape 

 Breton, and much of the surface of Nova Scotia and New Brunswick, 

 are confessedly unstudied and almost unknown; secondly, because 

 the incredible thickness assigned to the coal measures throws doubt 

 upon the positions assigned to the unconformable horizons ; thirdly, 

 because the coal-beds themselves stand almost vertical in many places 

 round the shores; fourthly, because the mountains of Nova Scotia, 

 with apparently conformable Carboniferous limestones, have appar- 

 ently an Appalachian structure and aspect, have suffered vast denu- 

 dation, exhibit cliff outcrops and section ravines, and may just as well 

 have carried coal upon their original backs as we can prove that our 

 Tiissey, Black Log, Nescopec, Mahoning, Buffalo, Tuscarora, Brush, 

 and other Silurian and Devonian mountains did. There is an immense 

 unconformable chasm in the column west of the Hudson River, and 

 the Catskill Mountains over it have no coal upon their backs ; but 

 the coal comes in regularly enough on them at the Lehigh (a less 

 distance than from Sydney to St Peters, or from Pictou to Windsor), 

 and the unconformability 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 suggested 

 that they may prove to be the equivalents of the system oi productive 

 coal measiu^cs ; 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 measures. 

 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 in which the Glace Bay coals apply, but hope that his accu- 

 rate 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 ; because the doctrine of isolated basins, 

 when unfounded or overapplicd, is as injurious to lithological truth 

 as the careless identification of surface aspect may at any moment 

 prove to palajontology. I willingly leave to accomplished palaeon- 

 tologists like Professor Dawson, the discussion of the grand general- 

 ization 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 



K 



