Abstract
On the outcrop of the basalt lavas at Kawajiri-misaki (Cape Kawajiri), the present author has carried out a fairly continuous sampling of a number of test specimens from an area of one meter square of the outcrop belonging to entirely one rock block and has confirmed that the normal and the reverse natural remanent magnetism (N. R. M.) are found intermixed side by side in the very outcrop. On the other hand, the results of the thermo-magnetic analyses of the lava specimens suggest that the magnetic mineral responsible to the normal N. R. M. is predominantly a titanomagnetite of a phase having intermediate Curie point, whereas those to the reverse N. R. M, poly-phase having lower and higher Curie points than the intermediate. N. Kawai has recently proposed the idea that the self-reversal of remanent magnetism of rocks is possible to occur when the reverse magnetism of poly-phased titanomagnetites overcomes the normal of the pre-existing, single-phased, parent one of which the exsolution has produced the poly-phased ones. Both the field evidence showing the positional close intermixing of the normal and the reverse magnetizations in the same lavas and the results of the author's laboratory experiments to prove the exsolution do not seem to favour the geomagnetic field reversal hypothesis.
