The stability and significance of magnetism in sedimentary rocks

This study was undertaken to investigate whether sedimentary rocks can retain directions of magnetization through long intervals of geologic time. The method of investigation is to observe the angular relations of the directions of residual magnetization to the bedding in deformed structures, or in beds that were laid down in a random manner. Systematic relationships found indicate that the direction of magnetization in certain selected sedimentary rocks remains unchanged for at least 200 million years.