The formation of rattle stones and the climatological factors which limited their distribution in the Dutch pleistocene, 1. The formation of rattle stones

Abstract

In the Dutch pre-Riss deltaic beds rattle stones are found which are generally believed to have been formed by concretionary deposition of ferric oxide hydrate around a non-concretionary centre. From a number of textural characteristics as well as from certain physical properties and an analysis of their clastic components, this interpretation can be shown to be incorrect. All evidence strongly suggests that these stones are chemically transformed allochthonous siderite concretions, deposited prior to such transformation and contemporeaneously with the sediments in the beds where they occur at present. That this transformation by oxidation must have been epigenetic is concluded from the fact that abrasion and cleavage due to transport had occurred in the pre-oxidized state. Individual differences in texture and composition of the stones are most probably due to differences in composition of the original ferrous carbonate concretions, as well as to the extent of and oscillations in the oxygen supply during oxidation. A new definition of rattle stones is formulated.