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ave a tapering unequal surface, must be formed on, or under, the side of a coast composed of pointed rocks and precipices, or some such uneven surface. For we cannot suppose that snow alone, as it falls, can form, on a plain surface, such as the sea, such a variety of high peaks and hills, as we saw on many of the ice-isles. It is certainly more reasonable to believe that they are formed on a coast whose surface is something similar to theirs. I have observed that all the ice-islands of any extent, and before they begin to break to pieces, are terminated by perpendicular cliffs of clear ice or frozen snow, always on one or more sides, but most generally all round. Many, and those of the largest size, which had a hilly and spiral surface, shewed a perpendicular cliff, or side, from the summit of the highest peak down to its base. This to me was a convincing proof, that these, as well as the flat isles, must have broken off from substances like themselves, that is, from some large tract of ice. When I consider the vast quantity of ice we saw, and the vicinity of the places to the Pole where it is formed, and where the degrees of longitude are very small, I am led to believe that these ice-cliffs extend a good way into the sea, in some parts, especially in such as are sheltered from the violence of the winds. It may even be doubted if ever the wind is violent in the very high latitudes. And that the sea will freeze over, or the snow that falls upon it, which amounts to the same thing, we have instances in the northern hemisphere. The Baltic, the Gulph of St Laurence, the Straits of Belle-Isle, and many other equally large seas, are frequently frozen over in winter.[12] Nor is this at all extraordinary, for we have found the degree of cold at the surface of the sea, even in summer, to be two degrees below the freezing point; consequently nothing kept it from freezing but the salt it contains, and the agitation of its surface. Whenever this last ceaseth in winter, when the frost is set in, and there comes a fall of snow, it will freeze on the surface as it falls, and in a few days, or perhaps in one night, form such a sheet of ice as will not be easily broken up. Thus a foundation will be laid for it to accumulate to any thickness by falls of snow, without its being at all necessary for the sea-water to freeze. It may be by this means these vast floats of low ice we find in the spring of the year are formed, and which, after
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