The sedimentology and palaeoecology of the Westleton Member of the Norwich Crag Formation (Early Pleistocene) at Thorington, Suffolk, England

Abstract

-Extensive sections in the Thorington gravel quarry complex in eastern Suffolk include the most complete record to date of sedimentary environments of the Westleton Beds Member of the Norwich Crag Formation. New palaeoecological and palaeomagnetic evidence is presented, which confirms that the Member was deposited at or near a gravelly shoreline of the Crag Sea as sea level fluctuated during a climatic ameloriation within or at the end of the Baventian/ pre-Pastonian 'a' Stage (Tiglian C4c Substage).

The palaeontology and dating of the ‘Weybourne Crag’, an important marker horizon in the Early Pleistocene of the southern North Sea basin

“…The clast lithology of the gravels suggests derivation from the north by longshore drift (Hey, 1967, 1976but see Hamblin et al, 1997 with probable input from the early Thames from the south (Gibbard et al, 1998). The gravels are generally unfossiliferous but occasional casts of marine shells and other fossils have been found (Richards et al, 1999). They have been assumed to be of late Baventian to "Pre-Pastonian a" age (Gibbard et al, 1998).…”

“…including periglacial features at Öbel, Germany (Gibbard et al, 1995), the Westleton Beds (Richards et al, 1999), the Baventian/"Pre-Pastonian a" (Gibbard et al, 1998) and regressive (low sea-level) sequences with periglacial features (frost-cracks and cryoturbation) in the Beerse area of northern Belgium (Kasse, 1993). A recent reappraisal of the type sequences, however, suggested that this sand body in the Russel-Tiglia Egypte pit at Tegelen formed during the onset of local crevassing, casting serious doubt on its significance as an indicator of (supra)regional climatic deterioration (Westerhoff, 2009).…”

Reply: Middle Pleistocene sedimentation at Pakefield, Suffolk, England

“…We are also aware that heavy minerals and pebble lithologies are susceptible to reworking from pre-existing Quaternary or pre-Quaternary strata. For instance, the Westleton Beds of the Norwich Crag Formation are beach deposits composed of highly reworked local materials (Richards et al, 1999); however, by examining in detail the spatial and stratigraphical variability of their occurrence, it is possible to determine where the first appearance of lithologies occur within the sequence, and the relative proportions and types of reworked lithologies. See Lee et al (2004a) for a clear explanation of this process and clear evidence of the introduction of glacially derived sediment into the Bytham river system.…”