of Nova Scotia, 135 



times talcose and chloritic, often coarse and arenaceous, and asso- 

 ciated with beds of sandstone and quartzite, and with calcareous 

 layers. In some districts there are also extensive beds which have 

 the appearaneo of interstratified igneous products both of horn- 

 blendie and felspathic composition. The associated igneous rocks 

 are granite (which appears to be continuous with that of the coast 

 series and intrusive), syenite, diorite, porphyry and compact fel- 

 spars. The more highly altered portions are penetrated by num- 

 erous veins of peroxide and carbonate of iron, with copper and iron 

 pyrites. 



These beds, as well as the overlying Devonian series, have been 

 thrown into folds, varying in direction from east and west to 

 north-east and south-west, and have been at the same time 

 much altered and disturbed by plutonic rocks. They afterwards 

 suffered extensive denudation, forming both anticlinal and syn- 

 clinal valleys, in which were deposited beds of the carboniferous 

 system, and of the New Red Sandstone of Nova Scotia, a 

 deposit still of uncertain age.* This denudation has appar- 

 ently been so complete as to remove from view nearly all the softer 

 and least altered beds, the remains of which appear principally at 

 the margins of the valleys now filled by the carboniferous series. 

 Even in these exceptional spots they have in some instances been 

 farther obscured by trappean eruptions of carboniferous or later 

 date. The following are the principal localities in which I have 

 been able to obtain determinable fossils. The geographical posi- 

 tion of these points is noticed in the accompanying map. (Fig. 1, 



p. 132.) 



Arisaig. 



Near this place, at the extreme northern limit of the Silurian 

 system on the eastern coast of Nova Scotia, is one of the most in- 

 structive sections of these rocks in the province. At the eastern 

 end of the section, where they are unconformably overlaid by 

 lower carboniferous conglomerate and interstratified trap,f the 

 Silurian rocks consist of gray and reddish sandy shales and coarse 

 limestone bands dipping south at an angle of 44°. The direction 

 of the coast is nearly east and west, and in proceeding to the east- 

 ward, the dip of the beds turns to south 30^ west, dipping 45°, 



* See Journal Geol. Society, Vol. 4, and Acadian Geology. 

 fSee papers by the author in Proceedings Geological Society, 

 1843-4. 



