Stratigraphy and palaeoenvironments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England

Abstract

This study uses a variety of criteria to examine short-range correlation within the Crag deposits in order to assess the validity of longer-range correlations within the British Pleistocene stage system. To this end, six rotary cored boreholes spaced at 0.5-1.0 km intervals were drilled along a north-south-aligned traverse between Aldeburgh and Sizewell, Suffolk. These show that the thick Red/Norwich Crag sequence is confined to a deep, sharply bounded basin, which is of probable erosional rather than tectonic origin. The undisturbed borehole core material enabled an assessment of the limits of stratigraphic resolution within these dominantly high-energy, shallow marine sediments to be made. Subdivision of the sequence was done on the basis of lithostratigraphical and biostratigraphical (foraminifera, pollen and spores, dinoflagellate cysts, and molluscs) criteria; chronostratigraphical methods (palaeomagnetism and amino acid chronology) were also applied. The various subdivisions indicated by each of these disciplines were in large part consistent, demonstrating that valid stratigraphic units had been identified. Only amino acid chronology did not indicate any obvious subdivision of the sequence. Three lithostratigraphical units were recognized within the thick Crag sequence. The lowest unit (AS-Lith 1) consists of coarse shelly sands interbedded with thinly laminated muds and fine sands. The middle unit (AS-Lith 2) consists of fine- to coarse-grained shelly sands arranged in two coarsening-upwards cycles. Units AS-Lith 1 and AS-Lith 2 are correlated on a lithostratigraphical basis with the Red Crag Formation of the adjacent Aldeburgh-Orford area to the south and are named the Sizewell Member and the Thorpeness Member respectively. The uppermost unit (AS-Lith 3) comprises fine- to medium-grained, well-sorted sands; it correlates with the Chillesford Sand Member of the Norwich Crag Formation of the adjacent Aldeburgh-Orford area. The Sizewell Member of the Red Crag Formation is normally magnetized and palaeontologically distinctive. The pollen, foraminifera and dinoflagellate assemblages firmly establish it as Pre-Ludhamian in age, and probably equivalent to an interval within the Reuverian C to Praetiglian Stages of the Netherlands. The Thorpeness Member of the Red Crag Formation is less easy to place within the British Pleistocene stage system. It is reverse magnetized, at least in part, and foraminifera assemblages suggest possible correlation with the Ludhamian Stage. No identifiable pollen or dinoflagellate assemblages were obtained. The Chillesford Sand Member of the Norwich Crag Formation is largely unfossiliferous but the borehole material has yielded a single pollen spectrum that suggests correlation with the Bramertonian Stage.

The Lower Pleistocene stratigraphy of the Ormesby Borehole, Norfolk, England

“…PAB a spectra resemble those from basal Crag sediments at Sizewell (West & Norton, 1974;Zalasiewicz et al 1988), although at Ormesby percentages of pine are slightly lower and frequencies of Ericales higher. A regional vegetation of pine-dominated woodland with some heathland is indicated.…”

“…PAB a is regarded as evidence of a Pre-Ludhamian pine forest similar to that seen at Stradbroke (Beck, Funnell & Lord, 1972) and Sizewell (West & Norton, 1974;Zalasiewicz et al 1988). PAB b is similar to Lu 2 (Thurnian), but differs in some important aspects (see section 5 above).…”

“…Reineck & Singh, 1973). Some indicators, such as the bioturbation of the shelly sand by crustaceans and the assemblage of dinoflagellate cysts, Zalasiewicz et al 1988. Contours drawn on the base of the Red Crag and Norwich Crag formations at 20 m intervals.…”

Sporadic Pliocene and Pleistocene brachiopods in Naturalis Biodiversity Center (Leiden, the Netherlands): Records from the Mediterranean, and the North Sea Basin

“…55), RGM.1309906 Brightwell (Suff olk), Brightwell Hill, abandoned sandpit, 52.039167 N, 1.280000 E. Pliocene, Piacenzian, Red Crag Formation ("Newbournian Red Crag"), collected by A. W. Janssen, 1 April 1970. Stratigraphy and palaeoenvironments of the Red Crag was discussed in detail by Zalasiewicz et al (1988).…”

The Neogene and Quaternary Clay‐with‐flints north and south of the English Channel: comparisons of distribution, age, genetic processes and geodynamics

“…The Red Crag was deposited around 2.4 Myr ago (Zalasiewicz et al, 1988;Jones and Keen, 1993) on a wide Plio-Pleistocene coastal plain, and the sea-level at this time, the Gelasian (=Tiglian), was about 30 m above its present level (Haq et al, 1987;Hardenbol et al, 1997). This suggests that the Gelasian coastal plain was later tilted so that the Rothamsted site was uplifted by 100 m (Fig.…”