Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/938

 with a block of trap(?) so large that it looked, even at a distance, like a good-sized house.

6. Life near the ice-fjords. — In the immediate vicinity of the Jakobshavn ice-fjord (and I take it as the type of the whole) animals living on the bottom were rare, except on the immediate shore or in deep water ; for the bergs grazed the bottom in moderately deep water to such an extent as almost to destroy animal and vegetable life rooted to the bottom. In this vicinity bunches of algae were floating about, uprooted by the grounding bergs, and the dredge brought up so little material for the zoologist's examination that, unless in deep water, his time was almost thrown away. Again, the heads of the inlets, unless very broad and open to the sea, are bare of marine life, the quantity of fresh water from the subglacial stream and the melting bergs being such as to make the neighbourhood (as in the Baltic) unfavourable for sea-animals. Some inlets are said to be so cold that fish leave them. I have not been able to confirm this in the Arctic regions. When stream-emptying lakes fall into the head of these fjords, having salmon in them, then seals ascend into the lakes in pursuit of them. Other localities, owing to the capricious distribution of life, would be barer or more abundantly inhabited. Again, in shallow inlets, except for Crustacea or other free-swimming animals, the bottom, continually disturbed by the dropping of moraine or the ploughing up of bergs, would be unfavourable for life. Accordingly, if the bed of the Arctic Ocean in these places were raised, and we found the mouth of a valley with laminated beds of clay rich in Arctic shells, and the head bare of life, but still showing that the beds had been assorted by marine action, supposing we were (as in Scotland) ignorant, except by analogy, of the history of this, should we not feel justified in saying that the beds at the one place and the other were deposited under different conditions, and were in all likelihood of different ages? How just that apparently logical inference would be I need scarcely ask.

II. Action of Sea-ice.

We have in the previous section in the most outline form sketched the subject of Greenland glacial action. As the object of this paper is not to form a summary of our knowledge on the subject, I have not entered into a discussion of any points on the physics of ice, further than was necessary to a right understanding of the subject in hand. Suffice it to say that all sea-ice forms originally from the "bay-ice" of the whaler, as the thin covering which first forms on the surfaces of the quieter waters is called, and that this " bay- ice" is entirely fresh, the effect of arctic freezing temperature being to precipitate the salt. Hence, when we talk of the temperature requisite to freeze salt water, it is merely equivalent to saying that this temperature is requisite for the precipitation of the saline constituents of the water. The water of the arctic sea is, according, to Scoresby, of the specific gravity 1.0263. At this specific gra-