[bailey] the bay of FUNDY TROUGH 111 



distinct evidence of its existence within that part of Nova Scotia which 

 now forms the southern boundary of the Bay of Pundy basin. 



It is usual to divide the supposed Cambrian rocks of Nova Scotia 

 into two distinct members, of which the lower consists chiefly of quart- 

 zites or fine sandstones, with much thinner intercalated slates, and the 

 upper almost wholly of slates, partly light coloured or banded, but mostly 

 very black and pyritous. The thickness assigned to the former by G-ilpin 

 is 9,000 ft., by Mr. Campbell it is made 10,000 ft., while W. F. Prest, from 

 measurements both on the Sissaboo and at Waverley, has estimated the 

 same thickness as high as 1G,000 ft. It is doubtful whether, in a region 

 so extensively folded and faulted as this, any estimates of thickness can be 

 looked upon with confidence ; but no one who has made sections across 

 the supposed Cambrian belt, anywhere between Halifax and Shelburne, 

 can doubt that the thickness, with all allowance for probable errors, is 

 something enormous. That the beds, especially of the lower division, 

 should exhibit such great uniformity, as regards both their extension and 

 their depth, is scarcely less remarkable ; while their character is such as 

 to indicate that they could hardly have been deposited in very deep water 

 or that their source was very far distant. It is true that, as compared 

 with the Cambrian rock of New Brunswick, they lack the coarse red 

 beds usually (but not always) found there at the base of the system, but 

 apart from their arenaceous character, the occurrence of ripple-marks and 

 occasionally of pebble beds leaves little doubt of their shallow water 

 origin. And yet over the whole of southwestern Nov^a Scotia we find 

 nothing to indicate the source from which they came. On the contrary, 

 it is now known that, with the exception of the granite and small areas 

 of Eo- Devonian and Trias, to be presently noticed, no other rocks than 

 those of the Cambrian system (so called) are to be found over all this 

 region. As, moreover, there is reason to believe that the granite itself is 

 but an excessively metamorphosed condition of the Cambrian quartzites 

 (this raetamorphism not occurring, however, until a much later period), 

 we are forced to the conclusion that all the portion of Nova Scotia 

 under discussion was, during a large portion of Cambrian time, in a con- 

 dition of submei'gence, forming a portion of a subsiding trough, whose 

 southern and eastern limits cannot now be defined. 



As regards the slates which overlie the quartzites, it is evident that 

 they indicate a still deeper submergence, possibly to considerable depths. 

 Their thickness has been variously estimated at from -1,000 to 10,000 ft., 

 but if only 5,000 ft., this, if added to 10,000 ft., as a reasonable estimate 

 for the quartzites, would indicate for the whole Cambrian system in Nova 

 Scotia a subsidence of nearly three miles. It may be that this subsidence 

 will, in part, account for the remarkable absence of fossils in the Cam, 

 brian rocks, the presence of cold currents traversing the submerged area 

 being unfavourable to the growth or spread of organic forms. 



