Evidence for changes in the Earth's magnetic field intensity

Abstract Archaeomagnetic investigations based on the measurement of remanent magnetization in baked archaeological objects and rocks show considerable changes in the Earth's magnetic field in the historical past. The curve characterizing the Earth's intensity during the past 8500 years has its maximum around 400 to 100 b. c. when the field reaches 1.6 times its present intensity and its minimum around 4000 b. c.when the field drops to around 0.6 times its present intensity. On the smoothed curves with a periodical change of approximately 8900 years, changes with shorter periods are superimposed which can also be observed in declination and inclination. Results of archaeomagnetic investigations of samples from different areas on the Earth's surface are discussed with the aim of defining the whole world and non­-dipole changes in the field moment. Possible connexions between the Earth's magnetic field and 14C decay are discussed on the basis of magnetic results, and the approximate character of changes in the Earth's field during the past 20000 years is given.