520 ME. E. GILPIN ON THE GEOLOGY OP 



of Eiver Inhabitants. The available evidence points to the Devonian 

 age of these measures, as laid down by Mr. Fletcher ; but Sir J. W. 

 Dawson is inclined to refer part, at least, to the Silurian. Further 

 search may provide more fossil evidence, although, as Mr. Fletcher 

 remarks, the rocks consist generally of shallow-water deposits. 



The unconformability between this formation and the preceding 

 is much more marked than between it and the Carboniferous ; but 

 the unconformable junctions with the latter are strongly marked at 

 Arichat, Leunox Passage, and Guysboro Harbour by degrees of me- 

 tamorphism, included pebbles, and stratigraphical position. The 

 total thickness of the formation has not been ascertained, but the 

 dimensions of various sections would corroborate that of Lennox 

 Passage, where a vertical thickness of 10,000 feet has been measured. 



The measures, as described by Mr. Fletcher, are arenaceous, 

 argillaceous, and nacreous shales and sandstones, passing into grits 

 of grey, red, and purplish shades, with beds of conglomerate holding 

 quartzite and felsite pebbles. Limestones are met with at several 

 points, and, as at St. Peters, Pirates' Cove, &c., appear to mark an 

 upper horizon. At numerous localities masses of diorite and trap are 

 protruded among these measures. This is especially noticeable in the 

 vicinity of St. Peter's Canal. The canal itself is cut in a rock con- 

 sisting essentially of a greenish-grey and bluish mixture of horn- 

 blende and felspars, intersected by veins of quartz and felspar. In 

 the Indian Reserve, in the same district, the sedimentary rocks are 

 broken through by grey and greenish compact and granular diorite, 

 and pyritous epidotic felsite, traversed by veins of calcspar. At 

 Jerome Point &c. are found exposures of black, greenish, and purplish 

 compact or granular, rusty-weathering trap, which is sometimes 

 porphyritic or globular, and charged with zeohtes, haematite, and 

 chlorite. At several points near St. Peter's and Guysboro, impor- 

 tant deposits of specular ore are met with, apparently associated 

 with these eruptive rocks. 



Caebonifeeotjs. 



This formation is conspicuously developed in Cape Breton ; and, 

 apart from the fisheries, to its coal and fertile limestorfe and gypsum 

 soils are due what measure of prosperity the island enjoys. Sir J. 

 "W. Dawson, in his ' Acadian Geology,' has arranged the Carbo- 

 niferous of the Lower Provinces in the following subordinate for- 

 mations : — 



1. The Upper Coal Formation, containing coal-formation plants, 



but only thin coal-seams. 



2. The Middle or Productive Coal Formation. 



3. The Millstone Grit. 



4. The Carboniferous Limestone, with marls, gypsum, &c. 



5. The Lower Coal-measures, holding some of the middle coal- 



formation fossils and thin coal-beds. 



Some districts do not present all these divisions, the lowest one 

 being frequently wanting or sparingly represented. And in many 



