An alternative form put forward by P. Kreichgauer, and recently brought up again by Wegener, explains the apparent variations in the position of the pole, not through a motion of the earth’s axis, but by the assumption that the firm crust has moved over the earth’s core so that the axis, remaining firm in its position, passes through different points of the earth’s crust. The cause of these movements is the centrifugal force of the great masses of the continents, which are distributed symmetrically about the earth. Imagine a single large continent resting on a sub-fluid magma in temperate latitudes. Centrifugal force acting on this continent tends to drive it towards the equator. There is thus a tendency for the latitude of Europe to decrease. Similar forces acting through geological ages have caused the poles and equator to wander at large over the earth’s surface, and also caused the continents to shift their positions relatively to one another. According to Wegener, in the Oligocene there was only a single enormous continent, America being united to Europe and Africa on the one hand, and through Antarctica to Australia on the other; while the Deccan stretched south-westwards nearly to Africa. The poles were in Alaska and north of the Falkland Islands. The treatment in Kreichgauer’s original book is speculative and at times fanciful; Wegener’s treatise appears to demand more respectful attention, but is open to some vital objections. In the first place, theories of this class demand that the glaciation occurred in different regions at widely different times, whereas we shall see in the following pages that the evidence points very strongly to a double glaciation during the Quaternary occurring simultaneously over the whole earth. This objection, which was fatal to Croll’s theory in its original form, is equally fatal to theories of pole-wandering as an explanation of the Quaternary Ice Age. Secondly, we know that the last phase of this glaciation, known as the Wisconsin stage in America and the Wurmian in Europe, was highly developed only 20,000 years ago, and probably reached its maximum not more than 30,000 years ago. In the last 5000 years there has been no appreciable change of latitude, at least in Eurasia; and it seems impossible for the extensive alterations required in the geography of the world by Wegener’s theory to have taken place in so short a time.