PALAEOMAGNETISM AS A MEANS OF DATING GEOLOGICAL EVENTS

Abstract

THE SCIENCE of palaeomagnetism evolved from studies of rock magnetism two facts became evident. The first is that certain igneous and sedimentary rocks are found to be permanently magnetized in the direction of ambient earth’s magnetic field at the time of their formation; the second is that this direction is commonly different from that of the earth’s now, and that in general the older the rock is, the greater is this difference. Further investigations revealed that accompanying this so-called wandering was another characteristic of the earth’s field: it appears have reversed its polarity several times in the geological past. Furthermore,