Study on the variations of geomagnetic-field intensity during the quaternary in special reference to thermomagnetic measurements on volcanic rocks

Thermomagnetic measurements have been made on thirteen samples of Quaternary volcanic rocks of different episodes from three localities by Thellier's method. Paleomagnetic field intensities for the three Quaternary sub-periods have been obtained: 0.62 for Early Pleistocene, 1.01 for Middle Pleistocene and 1.57 for Late Pleistocene with respect to the present magnetic field intensity. The results indicate that the geomagnetic field intensity has been increasing since Pleistocene time, and there exists a close relationship between paleomagnetic field intensity and climatic changes, i.e., the climate trends to become colder with increasing paleomagnetic field intensity, and vice versa.