The Age of Flint

Abstract

A HUNDRED years have elapsed since Mantell opened the controversy regarding the formation of flint, but hitherto, despite a voluminous literature on the subject, the crucial point, the time of formation, has remained undecided. The main issue has been narrowed down to one of two possibilities: either the flint was formed contemporaneously, by precipitation of silica gels on the sea-floor, or it was formed subsequently to the deposition of the Chalk, by the solution and segregation of silica disseminated through the chalk chiefly from the remains of sponges. The arguments in favour of the rival views are fairly evenly divided, and a strong case can be made out for both contemporaneous and subsequent formation. In fact, almost every observation can be made to fit in equally well with either view; and, like the evidence, so the supporters of the theories, past and present, are evenly divided. An infallible criterion of the age of flint is, therefore, a prime necessity, and the purpose of this note is to suggest one, of which the only remarkable feature is its extreme simplicity. The condition of the sponge remains found in flint is in itself adequate proof that the formation was subsequent.