Studies of the magnetic anomalies paralleling ocean ridges have furnished partisans of continental drift with decisive arguments. To take stock of this important question, my colleague Thellier and I decided in the early summer of 1967 to make it the subject of the annual seminar on Earth physics for the school year 1967-68. Although research was still developing rapidly, the General Assembly of the International Union of Geodesy and Geophysics held in Switzerland in September, particularly some of the meetings in Zurich under the auspices of the International Committee for the Upper Mantle,...

Studies of the magnetic anomalies paralleling ocean ridges have furnished partisans of continental drift with decisive arguments. To take stock of this important question, my colleague Thellier and I decided in the early summer of 1967 to make it the subject of the annual seminar on Earth physics for the school year 1967-68. Although research was still developing rapidly, the General Assembly of the International Union of Geodesy and Geophysics held in Switzerland in September, particularly some of the meetings in Zurich under the auspices of the International Committee for the Upper Mantle,...