Generally the fact that residual magnetization of igneous rocks is greater than sedi-mentary rocks is well known. The authors took an interest in the measurements of residual megnetiza-tion of sedimentary rocks. Residual magnetization of rock samples of sandstone and mudstone were measured by the Astatic magnetometer.
An ideal residual magnetization curve which was measured by this magnetometer was a sine curve. In the samples tested the induced magnetization appeared under the influence of terrestrial magnetic field, and this magnetization effect was marked by a shift of the sine curve. There were some samples among those tested which didn't show typical sine curves. Using the harmonic analysis the authors could separate the residual magnetization and the induced magnetization.
