River terrace sequences: templates for Quaternary geochronology and marine–terrestrial correlation

Abstract

Fluvial sequences, particularly terrace staircases, represent archives of Quaternary palaeoclimatic fluctuation and can serve as stratigraphical frameworks for geochronology and for correlation with other depositional environments, in particular, the global marine oxygen isotope record. Fluvial lithostratigraphical frameworks also provide contexts for records, from fossils and artefacts, of faunal evolution and human occupation; conversely, both records can be means of relative dating of riverine sequences.Three fluvial sequences are examined as case studies. First is the Severn-Avon system in the English Midlands, which has biostratgraphical evidence and an amino acid geochronology, together with marker inputs from three different glaciations. The Somme sequence of northern France, famous for its Palaeolithic artefact assemblages, again has biostratigraphy and an amino acid geochronology and has also been dated with reference to overlying loess/palaeosols sequences. The fluvial terraces of the River Arun, the final case study, lack dating evidence but are interspersed within the Sussex raised beach staircase. Although various lines of evidence suggest that the rivers discussed have formed terraces in response to climatic fluctuation, an intriguing difference is that interglacial sediments occur at the bases of terrace formations in the Severn-Avon, whereas in the Somme they occur at the tops of sequences, beneath loessic overburden.

Climatically controlled river terrace staircases: A worldwide Quaternary phenomenon

“…In the River Avon (English Midlands), the similar basal situation of interglacial remnants within terraces (Maddy et al, 1991) led to the same interpretation (Bridgland et al, 2004a).…”

An optically stimulated luminescence dated Middle to Late Pleistocene fluvial sequence from the western Solent Basin, southern England

“…For this reason, well-constrained chronological frameworks for river terrace deposits are crucial to enhance our understanding of Palaeolithic occupation of the landscape (cf. Bridgland et al, 2004a). For example, the Thames sequence is constrained by a relative mammalian biostratigraphy, enabling Bridgland (1994Bridgland ( , 1995 to attribute the earliest appearance of the Levallois technique within the upper part of the Lynch Hill Gravel (Lacaille, 1940) to a time equivalent to the MIS 9/8 transition.…”

Rivers through geological time: the fluvial contribution to understanding of our planet

“…Numerically these artefacts are dominated by waste material from the manufacture of stone tools, although the tools themselves represent a conspicuous and highly informative body of data. In the Pleistocene, the cyclic nature of the fluvial record, largely in the form of river terraces, can be used as a framework for the chronology of the terrestrial record, bridging between the restricted windows of time within which geochronological (numerical) dating is possible (Bridgland et al, 2004). Fossils, and even archaeology, where present, can assist in establishing this framework.…”