COAST OF NOVA SCOTIA — PREST. 147 



be given to the theory that the granite boulder dredged by the 

 Challenger one hundred miles off the coast denotes the extension 

 of glaciers and consequent existence of land that much farther 

 south. 



Speculations regarding the time wlien this doubtful southern 

 extension of glaciers took place might not be altogether futile if 

 we only knew the rate of deposition on that part of the sea 

 bottom. No doubt the above mentioned boulder was on the sur- 

 face or within a few inches of the surface of the mud or clay 

 composing the bottom, and the inference drawn from these facts 

 will be, that either the annual deposition is inconceivably small 

 or that the boulder was dropped from a passing iceberg long 

 subsequent to the great ice age. 



As to the time when the Musquodoboit River began to excav- 

 ate its channel, an approximate estimate might be made, provid- 

 the rate of erosion were known. The rock is a hard quartzite 

 and slate, and with only the now existing denuding agencies its 

 excavation would be a work of many thousand years. To take 

 Sir Charles Lyell's calculations for the much softer rocks of the 

 Niagara, which is I think 33,000 years, we may arrive at a very 

 rough approximation. But as his figures have been often 

 disputed, we must rest content in the belief that many 

 thousand years ago our sea coast extended much further south, 

 and that had it remained so, Halifax would never have been the 

 chief Naval Port of the British North American squadron. 



