Geochronology and other uses of isotopic analysis

Abstract

The discovery that fossil assemblages could be used in setting up a stratigraphic column was the cornerstone of Phanerozoic geology. In Archaean rocks some ‘fossils’ do exist, but they are of very little stratigraphic use. Isotope geochronology is used instead: inevitably, radiometric dates cannot be used as an exact substitute for a fossil assemblage and the philosophical basis is subtly different. But just as the study of fossils had implications far beyond their narrow stratigraphie use, so geochronology provides information of great significance in understanding the early history of the Earth (Rutherford 1907).

... it is fearful then

To steer the mind in deadly solitude

Up the vague stream of probability

To wind the mighty secrets of the past

And turn the key of time.

H. Kirke White (1785–1806), Time