564 THE UPPER SILURIAN. 



ifcrous parts are Upper Silurian. Some portions of the altered rocks 

 may, however, be either Devonian or Lower Silurian. The first up- 

 heaval and alteration of the beds must have occurred long before the 

 beginning of the Carboniferous period, but igneous action continued, 

 especially in the eastern part of the province, during and perhaps after 

 that period. In their original state these slates and quartz rock, and 

 their iron ore, must have been shales, sandstone, and iron sand, 

 abounding in fossil remains, and with layers of calcareous matter mostly 

 made up of shells and corals. Over large tracts the fossils have been 

 obliterated by metamorphism, and a perfect slaty structure has been 

 induced. 



In Cape Breton, rocks similar to those above described constitute 

 the several irregular tracts of mctamorphic and igneous country to 

 which the colour of this group has been assigned. Syenite and por- 

 phyry are extensively developed in a line extending from St Peter's 

 along the east side of the Bras d'Or, in the country between little Bras 

 d'Or and the East Arm, in the high ridge extending to Cape Dauphin, 

 in the hills near the Bedeque, Middle, and Margarie Rivers, in those 

 near Mabou, and in the irregular tract at the sources of the Inhabitants 

 River, and River Denys. Slates are associated with them in these 

 places, but I am not aware that they contain any fossils. 



I am informed by Mr Brown that the elevated region occupying the 

 extreme northern part of Cape Breton, and of which I have seen only 

 the southern borders, consists, at least in the vicinity of the coast, 

 principally of red syenite and mica slate. Its interior is entirely 

 unknown to geologists ; but from its appearance as viewed from a 

 distance, I infer that it consists of a number of elevated ridges similar 

 to those of the Cobequid Mountains, and probably attaining an equal 

 elevation. The patches of Lower Carboniferous rocks which appear 

 at intervals along its margin, indicate that, like the Cobequids, it 

 formed a rocky island in the seas of the Carboniferous period.* 



We may now return to those portions of the rocks whose distri- 

 bution has been sketched above, in which fossil remains indicative of 

 their geological age have been found. The most important and in- 

 structive of these is Arisaig, in the county of Antigonish, a locality 

 to which the writer first directed the attention of geologists in a paper 

 published in the Journal of the Geological Society in 1848, and more 

 fully in a paper published in the " Canadian Naturalist," vol. v. ; and 

 which has subsequently been more minutely described by Dr Honey- 

 man. -J- For a knowledge of its fossils we are indebted principally to 

 Professor Hall, who described forty new species from this place in con- 

 * See Appendix. f Journal of the Geological Society, 1864. 



