[POOLE] FEATURES OF CONTINENTAL SHELF OFF NOVA SCOTIA 73 



uo satisfactory conclusions can be drawn of the presence or otherwise of 

 a further ea-^tward extension of the ancient river in times even more 

 remote. 



In a paper of mine read before this Society in May, 1903, a position 

 was assumed for a tributary' now sulmiL>r»ed to this great river which 

 must have drained the greater part of Eastern Canada in some preglacial 

 age and when the region had greater altitudes than it has to-day. The 

 tributary in question was located parallel to and but a few miles otf the 

 west coast of Cape Breton and its position was determined by laying 

 doyn on Admiralty charts the isobaths indicated by the recorded sound- 

 ings. The isobathic lines have also been extended further up the Gulf 

 beyond Prince Edward and the Magadalen Islands to the shores of New 

 Brunswick and the}- have shown other important tributaries flowing from 

 the south had descended to the grand canyon of the Gulf of St. Lawrence 

 into which opened a broad fjord parallel to the Gaspé peninsula. This 

 had two lu'anches represented now by the Bays Chaleur and ]\Iiramichi 

 receiving then as now the main streams of Northern New Brunswick. 



Besides the tributaries joining the preglacial river within the con- 

 fines of the Gulf, others also flowing north and eastward fell into it 

 south of Cal)ot straits. The drainage of the southern slopes of Cape 

 Breton highlands formed a fjord similar in character to the one men- 

 tioned h'ing off the Gaspé peninsula. It had St. Ann's Bay at its head 

 and was the outlet of streams finding passage northward by the Great 

 Bras d'Or and Sydney harbour. Then there is the arm of the sea known 

 as Mira river which is the head of another fjord but its mouth is obscure 

 being partly silted up by the glacial deposits disturbed by the coastal 

 currents which run so strongly by the projecting headlands of Scaterie 

 and its neighbourhood. Still another stream of greater magnitude 

 skirted the southern coast of Cape Breton and added its waters to the 

 flood of the ancient St. Lawrence before it made its final plunge over 

 the edge of the continent into the ocean's abyss.^ This stream came out 

 of Chedabucto Bay then a profound fjord, as indicated by the deep 

 soundings of 12-i fms., and probably made its channel in Carboniferous 

 strata, remnants of which are still left in Isle Madame, and along the 

 shore and then followed eastward the present coast of the island, to join 

 the great river near the Scatteriei bank. 



This fjord had two forks of which the smaller had its head in 

 Boman Valley 10 mile^ above the town of Guysboro following the con- 

 tact of two geological formations. 



The northern or main fork is no longer fed by a stream of fresh 

 water but now is occupied by the salt water strait of Canseau connecting 

 the marine waters of the Gulf with those of the ocean. 



