POLAR MOVEMENT AS INDICATED BY ROCK MAGNETISM

Abstract

Measurements of remanent magnetism have been carried out by geophysicists both in this country and in the British Isles in a broad sampling of Paleozoic sediments. The direction of magnetization of these rocks indicates that the positions of the earth’s magnetic poles were quite different in Paleozoic times from their positions today. Since it is felt that the magnetic poles are closely tied in with the spin axis of the earth, the locations of the magnetic poles, as averaged over space and time, should indicate the locations of the geographic poles. Determinations of magnetization of Mississippian concretions and other sediments of chemical origin in the Llano uplift area of Texas were made in our laboratory, and indicate pole positions in Carboniferous times consistent with observations made by Belshe in England and by Runcorn in Arizona. Cambrian pole locations, as found from samples in the same area, are included and compared with positions from other work. A few interesting data are shown from the Sawatch formation of Cambrian Age in Colorado.