BELT ON PRODUCTION OF LAKES BY ICE ACTION. 7i 



■of intense glaciation, such as the rounding of protuberant bosses of 

 rock, and the transportation of huge boulders, are of frequent 

 occurrence. The course of the main lines of scratchings varies 

 from N.N.E. to N. N. W., and the lines of the major axes of the 

 lakes and of the chains of lakes, have the same bearings. The 

 Shubenacadie lakes commence at Dartmouth, near Halifax harbour, 

 and stretch in an irregular northerly direction to the head of the 

 Shubenacadie river, a distance of twenty-two miles, and with the 

 river they occupy a great depression or valley, running from Cobe- 

 quid Bay to Halifax harbour, a distance of fifty miles. 



The largest of the chain, the Grand Lake, is eight miles long, 

 and in its deepest part its bottom lies seventy-four feet below the 

 mean level of the sea. The coast is indented with long, narrow, deep 

 bays or fiords, running in the same direction as the chains of lakes. 

 The glaciation of the rocks and the transportation of boulders 

 point to the agency of ice, and the only question undecided is, 

 whether we shall ascribe them to the action of glaciers or of 

 icebergs. Icebergs, laden with rocks and clay, and ploughing up 

 the bottom of the sea where they grounded, might be sufiicient to 

 account for the scratchings and for the transportation of boulders ; 

 but they do not furnish us with the power requisite to scoop out 

 deep channels and gorges, often continuous for scores of miles, in 

 hard rocks, which are as characteristic of a glaciated country as the 

 minor scratchings and groovings. In Nova Scotia, the whole coun- 

 try has been hugely grooved and furrowed, and heaps, or rather 

 hills of gravel, piled up on the sides and in the courses of the 

 channels excavated. This configuration of the country is best 

 explained, as it has been by Agassiz and others, by supposing that 

 it was covered by a vast accumulation of continental ice, moving 

 southward from the Arctic regions, which, when at its greatest 

 development scooped out the larger vallies and deep fiords, and 

 modelled the grander features of the country ; and during its retro- 

 gression, when continental ice enveloping the hills had wasted into 

 glaciers down the principal valleys, they, during their slow retreat, 

 left terminal moraines in their courses, and heaps of gravel and 

 angular blocks on their flanks. 



It is readily admitted that such lakes as are formed by the dam- 

 ming up of channels with heaps of clay and gravel, may have been 



