8 THE ROYAL SOCIETY OF CANADA 



In Nova Scotia rocks of Cambro-Silurian age have been reported 

 by Fletcher, Ami and others as occurring at various points, such as the 

 Arisaig region (mainly Silurian) the Mira river district in Cape Breton, 

 and others. These beds are marine in origin and indicate submergence 

 of the areas in which they occur, but no such deposits are found in 

 peninsula Nova Scotia, where, excepting the Eo- Devonian of the Anna- 

 polis region and the batholithic granites, the only rocks are those of 

 the Gold-bearing series of the Atlantic coast, of Pre-Cambrian age. 

 These may have been above the sea-level in Ordovician time and far 

 higher than at present, but there is no definite proof of this. 



Silurian 



The geographical conditions which characterized the Silurian 

 Era in Acadia are m_uch more clearly indicated than those of pre- 

 ceding eras — the rocks of this time being very widely distributed and 

 giving much more direct evidence of their origin. 



As in earlier periods a large part of the Acadian basin was below 

 the sea-level. Not only was this true of what is now the St. Lawrence 

 Gulf, but, to the westward of the latter, the waters spread over all 

 northern New Brunswick, north of a line extending from near Bathurst 

 to the Maine frontier, the depression thus indicated being a portion 

 of what Dana long since termed "the Gaspe-Worcester trough." As 

 indicated by the organic remains found on Anticosti Island in the Gulf, 

 at Dalhousie in New Brunswick, in Aroostook county, Maine, and 

 further west, the trough was occupied by a shallow coral-growing sea, 

 abundantly tenanted b^^ forms of life indicative of a warm temperature. 

 In southern New Brunswick were other troughs such as have been 

 already indicated in connection with the discussion of earlier periods, 

 but here the waters were shallower and more turbid, limestones and 

 corals are of rare occurrence and the deposits are mainly argillaceous 

 or sandy, being, as further indicated by their fossils, such as would 

 naturally accumulate where heavy sedimentation would be in progress 

 and current action powerful. In both cases a noticeable feature is 

 the presence and extent of volcanic action. Evidences of such action 

 are especially noticeable around Passamaquoddy Bay, where they are 

 now represented by such eminences as Chamcook mountain, Troaks 

 mountain, McMasters island and Moose island (Eastport) and are 

 so distributed as to indicate that the Bay referred to was at that 

 time not only clearly differentiated, but was a focus of intense vol- 

 canic activity. Similarly in Northern New Brunswick the disposition 

 of the volcanic rocks around the shores of the Bay Chaleur is such as 

 to indicate that this depression also was clearly defined in Silurian 



