858 SUTHERLAINTD, DAVIs' STRAIT AND BAFFIN'S BAY. 



Davis' Strait. This difference is certainly small, but still it is on 

 the favourable side ; and when we associate with it the diiferent 

 structure of the rocks and also the diminished, supply of vapour 

 during the winter months, we have a faint approximation to the 

 true cause why the glacier preponderates so largely in one direction, 

 while it is entirely absent in another. The fact too that large 

 sections of the coast-ice, before it Avas generally detached from the 

 land, became dissolved by the streams discharging the melting 

 snows of the North -Georgian Islands into the sea, may be 

 taken as an additional proof that the summer heat was positively 

 higher than was necessary for the conversion of snow into water. 

 Glaciers. — The travels of Prof. J. Forbes and of Agassiz in the 

 Alps have so fully established the true theory of the descent of 

 glaciers, which is applicable also to Greenland, as to render any 

 remarks on this head almost unnecessary. The introduction of 

 extraneous matter into the substance of the ice to be borne along 

 must be the same in every country. And so also must be the 

 deposition of moraines at the angles where the glacier begins to 

 protrude beyond the land, whether they occur at the sea-level, or 

 at rapid turnings at higher elevations. This deposition arises 

 from the dissolution of a portion of the ice rich in earthy matter 

 consequent upon increased freedom of exposure to the action of the 

 sun, and also from mechanical displacement of the rocky matter 

 by the advancing mass of the glacier. This was remarkably well 

 seen at the north side of the Petowak glacier, near Cape Atholl, 

 both at the sea-level and at an angle two miles further up the side 

 the glacier. 



The concentric and wavy appearance of the glacier-surface so 

 often noticed in the Alps, is remarkably well seen in the vicinity 

 of Cape Saumarez and of Cape Alexander, and also in Bardin Bay. 



Both Prof. Forbes and Agassiz agree in attributing the rough- 

 ness and irregularity of the surface of the glacier to the inequalities 

 of the bottom over which it has to pass, more especially in cases 

 where the action of the sun has not been distributed irregularly by 

 means of accumulations of extraneous matter. This is frequently 

 exemplified in the Arctic regions ; and, as in the Alps, large cre- 

 vasses are the result when a protruding mass is slipping imper- 

 ceptibly over a convex or ledged surface.* 



Although there certainly is a relation between the upper and 

 lower surfaces of a plastic glacier, even when it may be upwards 

 of 2,000 feet in thickness, still I must confess that in my opinion 

 we can scarcely attribute the regularly pinnacled appearance of 

 many a large iceberg and magnificent glacier to this cause. Some 

 glaciers and icebergs, again, are so flat and smooth on the upper 

 surface, that one can hardly conceive a rocky bottom beneath a 



* This is very well seen in the glacier of Petowak, and also in a glacier at 

 Cape Fitzroy, on the south shore of Jones' Sound. These crevasses are not 

 unfrequently filled up with mud, &c. brought down by debacles and other 

 means from the land on either side, and then they become frozen, thus cemen- 

 ing the whole mass firmly together, and perhaps forming part of the future 

 iceberg so long as a few cubic feet of it remain undissolved. 



