Archaeomagnetic and Palaeomagnetic Study of the Magnetic Field of the Earth in the Past 600,000 Years

Abstract

DIRECT observations provide information about the variation of the Earth's magnetic field only during the past 400 years, but these records can be considerably extended by archaeomagnetic and palaeomagnetic investigations. This article reports new information on variations of the Earth's magnetic field based on data gathered from three sources. These are (1) measurements of the thermoremanent magnetism of baked clay samples, which provide information about the past 6,800 years; (2) measurement of magnetic declination and dip on loess samples from a defile of layers in South Moravia 18 m thick; (3) investigation of the magnetization of baked clays and porcelanites produced by the underground combustion of Tertiary coal deposits in North Bohemia which have acquired high thermoremanent magnetization during the Quaternary—that is, during the last 600,000 years.