DISTRICT OF KICHMOND. 395 



sufficient quantity to decompose part of the sulphate of lime, and 

 produce sulphurct of iron ; and also to afford the colouring matter of 

 the nodules of black limestone found in the marl. Thirdly^ The pre- 

 valence for a considerable period of acid waters, combining with nearly 

 all the calcareous matter presented to them, and without interruption 

 from mechanical detritus. The anhydrite must have been deposited 

 with the common gypsum ; but, under the circumstances, it seems 

 difficult to account for its production, unless it may have been formed 

 by acid vapours, and subsequently scattered over the bed of the sea. 

 Fourthly, A return to the deposition of marl, under circumstances 

 very similar to those which previously prevailed ; and, lastly, The 

 restoration of the ordinary arenaceous and argillaceous depositions of 

 the Carboniferous seas. 



Of the gypsum veins found in the marls, those which are white 

 and fibrous may have been nearly contemporaneous in their origin 

 with the marl itself; those which are red and lamellar have been 

 subsequently introduced. The granular gypsum is in all cases a part 

 of the original deposit. The comparatively small quantity of red oxide 

 of iron in these marls and other associated beds is the most important 

 feature of difference between the deposit of Plaister Cove and those 

 of most other parts of this province. There is, however, a large 

 quantity of reddish and brown sandstone in the beds overlying the 

 gypsum, though on the whole these colours are less prevalent than in 

 the Carboniferous system of Nova Scotia proper. 



The rocks seen at Plaister Cove and its vicinity appear to be over- 

 laid in ascending order by a great thickness of black shales, which, 

 near Ship Harbour, contain shells of Naiadites. These shales are suc- 

 ceeded by true Coal measures, which, at Little River and at Can-ibou 

 Cove, contain seams of coal and a variety of characteristic fossil plants. 

 One remarkable peculiarity of these Coal measures is, that they have 

 been folded up by lateral pressure, so that they are often vertical, and 

 that the limestones with marine shells and the gypsum, are often 

 brought into immediate contact with masses of these disturbed Coal 

 measures. Coal measure beds in a less disturbed condition extend 

 up the River Inhabitants nearly to its sources, and occupy the 

 country between that river and the southern part of the Bras d'Or 

 Lake. The Lower Carboniferous limestone appears on the north-west 

 arm of River Inhabitants, at West Bay, at Lennox Passage, on Isle 

 Madame, and at St Peter's. At Lennox Passage it is associated with 

 a great bed of excellent gypsum, and contains an abundance of fossil 

 shells. At St Peter's it is non-fossilifcrous, and rests against syenite 

 and metamorphic slates, forming the western margin of a large tract 



