“Suppose we find scattered over a field a number of largish masses of stone, which are entirely different in character from the rocks found in the neighbourhood. The question arises, how did those stones get into that field? Three explanations are proposed. One: that they are the products of former volcanic action; two: that they were brought from a distance by human agency; three: that they were carried thither from some distant country by icebergs. Now each of those explanations involves certain consequences. If the stones are volcanic, then they were once in a state of fusion. But we find that they are unaltered limestone and contain fossils. Then they are not volcanic. If they were borne by icebergs, then they were once part of a glacier and some of them will probably show the flat surfaces with parallel scratches which are found on glacier-borne stones. We examine them and find the characteristic scratched surfaces. Then they have probably been brought to this place by icebergs. But this does not exclude human agency, for they might have been brought by men to this place from some other where the icebergs had deposited them. A further comparison with other facts would be needed.