On the territory of the Russian platform crystalline basement is overlain by a cover of sedimentary deposits, the thickness of which reaches several kilometers. One of the tasks of the aeromagnetic survey (V.N. Zander expedition, 1959-1961) was to determine the buried relief of the basement in connection with the search for oil and gas bearing structures in the sedimentary cover. The main method of solving the problem was calculation of the depth of the upper edge of magnetic bodies, usually corresponding to the surface of the crystalline basement.