146 ROYAL SOCIETY OF CANADA 



hills ranging from Cape Chignecto to Cape North, and the reappear- 

 ance of the Carboniferous Limestone series in the anticlines paralleling 

 the ranges on the gulf side. The southern of these anticlines extends 

 from Shepody bay through Wallace eastward, and is buried under Cape 

 Bear of Prince Edward Island. The eastern anticline is exposed in the 

 Magdalen Islands, paralleling the Cape Breton coast. 



A marked feature of the submerged river system is the varied 

 extent of the foreshore erosion, indicative of age. The charts of their 

 contours record the recession of the shore line to an unequal degree, the 

 least where the main channel makes its nearest approach to the old 

 rocks of Cape George, Cape Mabou and Cape St. Lawrence and the 

 greatest on the Prince Edward Island coast, where measured by the 

 scale of relative hardness of the respective series of rocks on the oppo- 

 site shores, data are furnished for an estimation of the period of 

 time that has elapsed since the present stage of erosion was entered 

 on. No conclusion has been reached as to the depth below the 

 present shore line at which this stage began to operate, but if 

 we assume for the sake of illustration 20 fathoms, then one mile from 

 shore at Cape Mabou is the equivalent of some ten miles at East Point, 

 and more than twenty-three miles at Cape Bear while Point Prim has 

 suffered a loss of fourteen miles at half that depth. 



A still greater elevation was necessary for the erosion of the lower 

 reaches of the river wdth a depth of 90 fathoms, while no less than 2,500 

 feet would be required to give to the ancient river channel through the 

 gulf an inclination to the ocean. This degree of elevation would allow 

 of the erosion of the present river estuaries and mud filled harbours. 



The data furnished by the river seem at least sufficient, without 

 assuming fault limitations to the Prince Edward Island rocks, whether 

 Permo-carboniferous, Permian or Triassic, to account for the absence 

 east of Pictou and on the Cape Breton coast of any remnants of the 

 softer series. On elevation occurring, the drainage off the high land of 

 the older and more resisting rocks round the gulf would be more effec- 

 tive along the contact and as denudation proceeded, the channels would 

 follow with the softer strata of the new series, and be wider and deeper 

 as we do find them on the east and west sides to the outlets on the great 

 St. Lawrence ancient valley. It would also be necessary to assume a 

 somewhat greater elevation to have occurred northward. On the coast 

 of Nova Scotia west of Pictou, the stages of the cycle had not advanced 

 so far as along the tributary rivers and the more exposed gulf shores 

 when subsidence took place; the lateral river of this part (represented 

 by the Straits of Northumberland), has been formed by the drainage 

 off the older rocks of the southern rim, but being less exposed and pro- 



