An Analysis of the Geomagnetic Field Using Palaeomagnetic Methods

Two models representing the variation with time of the direction of the geomagnetic field are considered. In the first, the present geomagnetic field is rotated about the geographic axis; in the second fluctuations in the position of the magnetic dipole having a Fisherian distribution and centred on the geographical pole are considered.The dispersions of directions of magnetization at points on the earth's surface for both models are found to be latitude dependent, and for the first model the dispersions in the southern hemisphere are considerably greater than those at corresponding latitudes in the northern. The origin of dispersion of magnetization of rocks is discussed and a method of separating that due to secular variation of the palaeo-geomagnetic field is considered.