"26 BULLETIN OF THE NATURAL HISTORY SOCIETY. 



are really old lavas and ash-rocks, both of Post-Camliriau and 

 Pre-Cainbrian systems, orii^inall}' spread out in broad sheets, 

 but which, now, owing to the folding of the strata with which 

 they are interbedded, exhibit their woi'n edges at the surface, 

 and thus have the elongated out-crops which Dr. Gesner repre- 

 sented on his map. 



Gesner's "New Brunswick"* gives the latest view whioh 

 that author has expressed on the extent and arrangement of the 

 intrusiv'e rocks in that province. The granite in this work is 

 described in much the same terms as in his reports above cited. 



But in this work he divides the syenite ridge of his Second 

 Report! into two parts ; one of syenite extending from the 

 Kennebecasis through St. John County to Albert County! 

 corresponding in its western part to the syenite of the Lauren- 

 tion axis of the Dominion Survey Reports, and in its eastern 

 part to the syenites, etc., of the Huronian (Coldbrook) locks of 

 St. John County. 



The other division of the syenite ridge is its western part 

 and is called " trap." The places mentioned as being on thevj 

 course of this band, except Red Rock Lake, || show that its 

 western part is composed of the Ijeddecl traps which cap the 

 (Upper) Silurian system in Charlotte County ; its eastern part 

 consists of the bedded traps of the Kingston series. 



Dr. Gesner was thus by degrees learning to distinguish the 

 differences which exist between the effusive rocks and the 

 intrusive rocks forming the core or axis of the metamorphic 

 range traced by him in southern New Brunswick. His divisions 

 may be interpreted as follows : 



Granite. — The Devonian granite of the Nerepis range. 

 Syenite. — The intrusive Syenites of the Laurentian and eastern 



Huronian (Coldbrook) areas. 

 Traj). — The old lava flows and intrusive dykes of the Silurian 

 (Upper) and the Kingston series (Huronian). 



♦New Brunswick, with Notes for Emigrants, by Abraliani Gesner, F. G. S., ero. 

 London, 1847. 



1 Second Report, p. 2. % '• New Brunswiclt" p, M'Z § Op. cit, p. 343. 



Red Roclf Lake is among the intrusive granites. 



