251 



CHAPTER XV. 



THE CARBONIFEROUS HYHTEM—Continmd. 



CENTRAL CARBONIFEROUS DISTRICT OF NOVA SCOTIA AND ITS OUTLIERS — 



USEFUL MINERALS. 



Carboniferous District of Colchester and Hants. 



In this district, Avhich is as extensive as that of Cumberland, from 

 which it is separated by the Cobequid chain of hills, we have a very 

 great development of the limestones and gypsums corresponding to 

 the Napan and Pugwash rocks of Cumberland, and the Mountain or 

 Lower Carboniferous limestone of England, and a very small devel- 

 opment of the Coal measures. In other words, in the Carboniferous 

 period marine deposits were formed to a greater extent and perhaps 

 for a longer time on the south than on the north side of the Cobequid 

 chain, which, we shall presently see, was then a ridge probably not 

 so high, but perhaps nearly as continuous as at present. 



On consulting the map, it will be seen that tliis district is very 

 irregular in its form ; partly because the modern bay, with its fringes 

 of marsh and New Red Sandstone, penetrates into it, and partly 

 because it in like manner penetrates in long inlets, now river valleys, 

 into the older metamorphic hills to the eastward. Viewing this dis- 

 trict, then, as a portion of the dried-up bed of the Carboniferous sea, 

 its original shores can be observed both on the north and on the south. 

 Thus on the flanks of the Cobequids, the Lowest Carboniferous beds 

 consist of conglomerates ; the stones and pebbles of which are identical 

 with the rocks of the hills from which they have been derived, just as 

 the materials of shingle beaclies on modern coasts are derived from 

 neighbouring cliffs. In like manner, at the base of the Horton and 

 Ardoise Hills, the lowest beds consist of white sandstones composed 

 of the debris of granite, and shales made up of the mud produced by 

 the slow wasting of slate ; both of these materials being furnished by 

 the rocks of the hills. One difference, however, of a marked character 

 occurs on these opposite shores. The material of the lowest rocks on 

 the south side of the district is fine and almost destitute of pebbles ; 



