The evolution of periglacial patterned ground in East Anglia, UK

Abstract

During the Late Pleistocene, East Anglia experienced multiple cycles of periglacial activity. This research investigates whether chalkland patterned ground infilled with coversand developed during one or more glacial cycles or only during the last period of intensive periglacial activity to affect lowland Britain. Single grain luminescence ages from polygons and stripes at six sites in East Anglia suggest that the patterns experienced multiple phases of activity during the last 90-10 ka but do not date back to earlier glacial cycles. This activity is attributed to four main phases: (1) ~55-60 ka, (2) ~31-35 ka, (3) ~20-22 ka and (4) ~11-12 ka. Most sites show some activity around the Greenland Stadial 2a and the Younger Dryas Stadial, but polygons show a longer, more temporally and spatially varied record than stripes. Interpreted phases of activity mostly coincide with stadials within the last glacial-interglacial cycle, possibly at the end of climatic cold phases.Key words polygon, stripes, OSL, chalkland, coversand 2 2 IntroductionThe utility of relict periglacial landforms in understanding palaeoenvironments has often been hampered by age uncertainties and the potential for near-surface features to be a palimpsest formed by multiple phases of activity (e.g. Paris basin, Thiry et al. 2013). Despite the complex glaciological history, the East Anglia region of the UK (Figure 1) contains abundant near-surface relict periglacial landforms and aeolian coversands (Figures 2 and 3; e.g. West 1963West , 2007West , 2009Rose et al. 1985;Rothera, 2000;Scheib and Lee 2010). Rose et al. (1985) hypothesised that they formed during stadials in the Devensian (equivalent to the continental Weichselian; Marine Isotope Stage (MIS) 5d-MIS 2), particularly the final phase of periglacial activity to affect lowland Britain, during the Younger Dryas Stadial (equivalent to the Greenland Stadial 2 (GS1); ~12.9-11.55 ka, cf. Lowe et al. 2008). West and Williams (2012), in contrast, attributed initiation of patterned ground to earlier glacial periods. Murton and Kolstrup (2003) also suggested that some Pleistocene cryogenic wedge structures in NW Europe are poly-cyclic.This study aims to test if chalkland patterned ground infilled with coversand developed during one or more cycles of periglacial activity. Single-grain Optically Stimulated Luminescence (OSL) dating and detailed statistical analysis of the resultant OSL replicate data are used to establish the timing of sand deposition and/or reworking in order to determine the number of cycles of activity, their relative intensity and palaeoenvironmental significance in North Western Europe.[ Figure 1 here] The Geological and Climatic Setting of Central East AngliaEast Anglia possesses a generally low-lying relief with the strata of the Upper Cretaceous limestones (Chalk Group; British Geological Survey, 2010; Figure 3a) forming a distinctive escarpment that extends from the eastern margins of the Wash in northwest Norfolk, south-westwards through Norfolk and Suffolk and into Cam...

Glacial Lake Pickering: stratigraphy and chronology of a proglacial lake dammed by the North Sea Lobe of the British–Irish Ice Sheet

“…This further supports previous reports of significant lowland permafrost during the stade (e.g. Bateman et al ., ). Sediment from LFA4, dated to 10.1 ± 0.7 ka, most likely reflects coversand reworking into the early part of the Holocene, before the Sherburn sands were stabilized by the development of vegetation in the ameliorating climate of that time.…”

The Middle Pleistocene glacial evolution of northern East Anglia, UK: a dynamic tectonostratigraphic–parasequence approach

“…East Anglia borders the south‐western margins of the North Sea Basin and possesses one of the best archives of Middle and Late Pleistocene environmental change in northern Europe (Ehlers and Gibbard, ; Rose, ; Candy et al ., ; Ashton and Lewis, ; Lee et al ., ; Preece and Parfitt, ; Bateman et al ., ). The region was glaciated during the Anglian [Marine Isotope Stage (MIS) 12] and Late Devensian (MIS 2) glaciations (Fig.…”

Discriminating between subglacial and proglacial lake sediments: an example from the Dänischer Wohld Peninsula, northern Germany

“…Obscuration of true D e variability at the single aliquot level has been reported elsewhere stemming from the measurement of many grains simultaneously to produce an average luminescence signal (e.g. Arnold and Roberts, 2009;Bateman et al, 2014). We therefore focus on the single grain results in this paper.…”

“…In such cases an age model targeting the lowest component of D e data, such as the minimum age model (MAM; Galbraith et al, 1999), was more appropriate. Where sample D e distributions were non-normally distributed, multi-modal and with a high OD, the sample could be interpreted as partially bleached, and/or post-depositionally disturbed and/or having multiple age components (Bateman et al, 2003(Bateman et al, , 2007(Bateman et al, , 2014. In such cases the finite mixture model (FMM; Galbraith and Green, 1990;Galbraith et al, 1999) was considered.…”