There is another cause referred to by Professor Dana, which, to a great extent, must prevent the iceberg from having an opportunity of striating the sea-bottom, even though it were otherwise well adapted for so doing. It is this: the bed of the ocean in the track of icebergs must be pretty much covered with stones and rubbish dropped from the melting bergs. And this mass of rubbish will tend to protect the rock.[141] If icebergs cannot be shown _à priori_, from mechanical considerations, to be well adapted for striating the sea-bottom, one would naturally expect, from the confident way in which it is asserted that they are so adapted, that the fact has been at least established by actual observation. But, strange as it may appear, we seem to have little or no proof that icebergs actually striate the bed of the ocean. This can be proved from the direct testimony of the advocates of the iceberg theory themselves. We shall take the testimony of Mr. Campbell, the author of two well-known works in defence of the iceberg theory, viz., “Frost and Fire,” and “A Short American Tramp.” Mr. Campbell went in the fall of the year 1864 to the coast of Labrador, the Straits of Belle Isle, and the Gulf of St. Lawrence, for the express purpose of witnessing the effects of icebergs, and testing the theory which he had formed, that the ice-markings of the glacial epoch were caused by floating ice and not by land-ice, as is now generally believed. The following is the result of his observations on the coast of Labrador. Hanly Harbour, Strait of Belle Isle:—“The water is 37° F. in July.... As fast as one island of ice grounds and bursts, another takes its place; and in winter the whole strait is blocked up by a mass which swings bodily up and down, grating along the bottom at all depths.... Examined the beaches and rocks at the water-line, especially in sounds. Found the rocks ground smooth, _but not striated_, in the sounds” (_Short American Tramp_, pp. 68, 107). Cape Charles and Battle Harbour:—“But though these harbours are all frozen every winter, the _rocks at the water-line are not striated_” (p. 68). At St. Francis Harbour:—“The water-line is much rubbed, smooth, _but not striated_” (p. 72). Cape Bluff:—“Watched the rocks with a telescope, and _failed to make out striæ anywhere_; but the water-line is everywhere rubbed smooth” (p. 75). Seal Islands:—“_No striæ are to be seen at the land-wash in these sounds or on open sea-coasts near the present water-line_” (p. 76). He only mentions having here found striations in the three following places along the entire coast of Labrador visited by him; and in regard to two of these, it seems very doubtful that the markings were made by modern icebergs. Murray’s Harbour:—“This harbour was blocked up with ice on the 20th of July. The water-line is rubbed, and in _some places_ striated” (p. 69).