Dating of Fossil Shells with Electron Spin Resonance

Abstract

Electron spin resonance (ESR) dating of sea shells has been made using the paramagnetic defects produced by natural radiation. The total dose of natural radiation of the materials, termed the archaeological dose, has been determined from ESR signals of defects in sea shells from northern Japan whose ages are known from the sediments or from the radioisotope dating. An annual dose of about 0.03-0.04 rad/yr explains the age of shells from a few thousand to a million years. The new method of ESR dating will be useful for sediment age determination and for other geological studies.