One other possibility may be mentioned, although little stress should be laid on it. In _Earth and Sun_ it has been shown that the main storm track in both the northern and southern hemispheres is not concentric with the geographical poles. Both tracks are roughly concentric with the corresponding magnetic poles, a fact which may be important in connection with the hypothesis of an electrical effect of the sun upon terrestrial storminess. The magnetic poles are known to wander considerably. Such wandering gives rise to variations in the direction of the magnetic needle from year to year. In 1815 the compass in England pointed 24-1/2° W. of N. and in 1906 17° 45' W. Such a variation seems to mean a change of many miles in the location of the north magnetic pole. Certain changes in the daily march of electromagnetic phenomena over the oceans have led Bauer and his associates to suggest that the magnetic poles may even be subject to a slight daily movement in response to the changes in the relative positions of the earth and sun. Thus there seems to be a possibility that a pronounced change in the location of the magnetic pole in Permian times, for example, may have had some connection with a shifting in the location of the belt of storms. It must be clearly understood that there is as yet no evidence of any such change, and the matter is introduced merely to call attention to a possible line of investigation.
Any hypothesis of Permian and Proterozoic glaciation must explain not only the glaciation of low latitudes but the lack of glaciation and the accumulation of red desert beds in high latitudes. The facts already presented seem to explain this. Glaciation could not occur extensively in high latitudes partly because during most of the year the air was too cold to hold much moisture, but still more because the winds for the most part must have blown outward from the cold northern areas and the cyclonic storm belt was pushed out of high latitudes. Because of these conditions precipitation was apparently limited to a relatively small number of storms during the summer. Hence great desert areas must have prevailed at high latitudes. Great aridity now prevails north of the Himalayas and related ranges, and red beds are accumulating in the centers of the great deserts, such as those of the Tarim Basin and the Transcaspian. The redness is not due to the original character of the rock, but to intense oxidation, as appears from the fact that along the edges of the desert and wherever occasional floods carry sediment far out into the midst of the sand, the material has the ordinary brownish shades. As soon as one goes out into the places where the sand has been exposed to the air for a long time, however, it becomes pink, and then red. Such conditions may have given rise to the high degree of oxidation in the famous Permian red beds. If the air of the early Permian contained an unusual percentage of oxygen because of the release of that gas by the great plant beds which formed coal in the preceding era, as Chamberlin has thought probable, the tendency to produce red beds would be still further increased.