Intensity of Remanent Magnetization of Archæological Remains

Abstract

TWO recent contributions referring to the remanent magnetization of archæological material show the need for more experiments. Elsasser, Ney and Winckler raised doubts about the accuracy of dating by radiocarbon¹. Their argument was that radiocarbon is formed by the action of cosmic rays; that this action is in part governed by the intensity of the Earth's magnetic field; that this intensity varies—very considerably according to Thellier's study of Roman bricks^2,3; and that in consequence the initial activity of radiocarbon, from which the age of a specimen is deduced, must vary too. Atwater and Ellickson challenge the premise that Thellier's measurements are valid⁴. They suggest that incomplete combustion in ancient kilns might cause a reducing atmosphere in which the intensity of magnetization would be greatly increased.