Difficulties are, however, urged by other writers. We can see at once that as quick as the glaciers are removed the denuding forces of nature, which are constantly at work, would begin to rearrange the _débris_ left behind on the surface, and in the course of a few thousand years must effect great changes. Now, in some cases the amount of such change is so small that geologists are reluctant to believe a vast lapse of time has occurred since the glaciers withdrew. Mr. Geikie tells us of some moraines in Scotland that they are so fresh and beautiful “that it is difficult to believe they can date back to a period so vastly removed as the Ice Age is believed to be.”34 In our own country this same sort of evidence is brought forward, and we are given some special calculations going to show that the disappearance of the glaciers was a comparatively recent thing.35 It will be seen that these conclusions are somewhat opposed to the results previously arrived at. In explanation Mr. Geikie thinks the cases spoken of in Scotland were not the moraines of the great glaciers, but of a local glacier of a far later date. He thinks that the climate, while not severe enough to produce the enormous glaciers of early times, was severe enough to produce local glaciers still in Scotland.36 It is possible that a similar explanation may be given for the evidence adduced in the United States. We can only state that, according to the difference in climate between the eastern and western sides of the Atlantic Ocean, when the climate was severe enough to produce local glaciers in Scotland, it would produce the same effect over a large part of eastern United States down to the latitude of New York City.37 And while it is true there would not be as much difference in climate on the two sides of the Atlantic in Glacial times as at present, since the Gulf Stream, on which such difference depends would then have less force, still it was not entirely lacking, and the difference must have been considerable.38 Prof. Hitchcock has made a suggestion that whereas we know a period of several months elapses after the sun crosses the equator before Summer fairly comes on, so it is but reasonable to suppose that a proportionate length of time would go by after the eccentricity of the earth’s orbit became small, before the Glacial Age would really pass away. He accordingly suggests it may have been only about forty thousand years since the glaciers disappeared.39 At the close of the Glacial Age Paleolithic man vanished from Europe. This, therefore, brings us to the conclusion of our researches into what is probably the most mysterious chapter of man’s existence on the earth.