Aeromagnetic surveys. Principles, practice & interpretation / Аэромагнитные исследования. Принципы, практика и интерпретация

From the point of view of geomagnetism, the earth may be considered as made up of three parts: core, mantle and crust (Figure 1.1). Convection processes in the liquid part of the iron core give rise to a dipolar geomagnetic field that resembles that of a large bar-magnet aligned approximately along the earth's axis of rotation (Figure 1.2). The mantle plays little part in the earth's magnetism, while interaction of the (past and present) geomagnetic field with the rocks of the Earth's crust produces the magnetic anomalies recorded in detailed (e.g. aeromagnetic) surveys carried out close to the earth's surface.