XII EXPLANATION OF THE GEOLOGICAL MAP. 



occurring on this island are Lower and Upper Silurian or Upper Silu- 

 rian and Devonian. 



In Nova Scotia I have, as heretofore, trusted principally to my own 

 observations, and to those of Mr Brown in Cape Breton. Valuable 

 corrections of limit lines have been received from Rev. Dr Honeyman, 

 F.G.S. ; and I am indebted to Mr J. B. Moore of Montreal, Mr Poole 

 of Glace Bay, Mr Mosely of Halifax, and other friends, for MS. Maps 

 and Sections illustrating the distribution of the Coal formation in 

 Pictou and Cape Breton. I have also, on the Carboniferous districts, 

 consulted the Reports of Professor Lesley and Mr Lyman, and many 

 reports made in the interests of the several Coal Companies. 



The Laurentian and Huronian formations in Southern New Bruns- 

 wick are given according to the latest observations of Mr Matthew 

 and Professor Bailey. Some uncertainty may be supposed to rest on 

 the precise equivalency of these beds with the formations so named 

 in Canada ; but that they are below the base of the Silurian, and that 

 they correspond in mineral character with the Laurentian and Huronian, 

 cannot be disputed. 



The boundaries of the Lower and Upper Silurian, more especially 

 in Northern and Western New Brunswick, and in Western Nova Scotia 

 and Cape Breton, are still very uncertain, and the limits of the igneous 

 veins and masses occurring among these altered beds are only vaguely 

 known. One colour has been employed to represent all the intrusive 

 rocks associated with the formations older than the Trias. The most 

 important of these is the Granite of the age of the Newer Devonian ; 

 but there are also numerous dikes and masses of Syenite, Diorite, 

 Compact Felspar, Porphyry, and Dolerite, some of which may be newer 

 and others older than the Granite. I have endeavoured to indicate 

 some of the more important of these ; but there are numerous others 

 of minor dimensions which I have not attempted to delineate ; as 

 they could be given correctly only on a large scale, and after more 

 minute surveys of their courses and extent. 



In Northern New Brunswick, both Professor Hind and Professor 

 Bailey state that the granitic rocks constitute several bands, tra- 

 versing the Lower Silurian ; but as I do not know the limits of 

 these bands, I have adhered in the main to the colouring on Logan's 

 Map. In Nova Scotia, also, I have no doubt that whenever a detailed 



