Possible ice-rafted erratics in late Early to early Middle Pleistocene shallow marine and coastal deposits in northeast Norfolk, UK

Erratic clasts with a mass of up to 15 kg are described from preglacial shallow marine and coastal deposits (Wroxham Crag Formation) in northeast Norfolk. Detailed examination of their petrology has enabled them to be provenanced to northern Britain and southern Norway. Their clustered occurrence in coastal sediments in Norfolk is believed to be the product of ice-rafting from glacier incursions into the North Sea from eastern Scotland and southern Norway, and their subsequent grounding and melting within coastal areas of what is now north Norfolk. The precise timing of these restricted glaciations is difficult to determine. However, the relationship of the erratics to the biostratigraphic record and the first major expansion of ice into the North Sea suggest these events occurred during at least one glaciation between the late Early Pleistocene and early Middle Pleistocene (c. 1.1–0.6 Ma). In contrast to the late Middle (Anglian) and Late Pleistocene (Last Glacial Maximum) glaciations, where the North Sea was largely devoid of extensive marine conditions, the presence of far-travelled ice-rafted materials implies that earlier cold stage sea-levels were considerably higher.     

Middle Pleistocene biota of the early Anglian ‘Arctic Fresh-water Bed’ at Ostend, Norfolk, UK

At three sites along the North Norfolk coast, freshwater sediments containing arctic plants have been reported to occur immediately beneath the glacial deposits. The sections at Mundesley and Beeston are no longer visible but a small exposure of this ‘Arctic Fresh-water Bed’ has recently been rediscovered at Ostend near Bacton. The fossils from this deposit are distinctly high boreal/arctic in character, indicating a small, possibly ephemeral, pool in a generally open landscape supporting some dwarf shrubs and conifers. Noteworthy records include three beetle species (Pterostichus brevicornis, P. middendorffi and Helophorus obscurellus) that today have their closest occurrences on either the Kanin or Kola peninsulas in arctic Russia. A Mutual Climatic Range reconstruction on the limited beetle fauna suggests that the mean temperatures of the warmest and coldest months were between 9 °C and 11 °C and between −36 °C and −10 °C, respectively. Other noteworthy occurrences include the aquatic pulmonate gastropod Gyraulus rossmaessleri (second and earliest British record), the ostracod Amplocypris tonnensis (earliest British record), ground squirrel (Spermophilus sp.) and the first record of arctic lemming (Dicrostonyx sp.) from the Cromer Forest-bed Formation (CF-bF). The ‘Arctic Fresh-water Bed’ has been assigned to the Bacton Member of the CF-bF and formed during the early Anglian, correlated with Marine Isotope Stage (MIS) 12 of the deep sea record. The Ostend assemblage is therefore important in providing a glimpse of conditions that occurred during a major cold stage in the early Middle Pleistocene.     

Development of a subglacial drainage system and its effect on glacitectonism within the polydeformed Middle Pleistocene (Anglian) glacigenic sequence of north Norfolk,Eastern England

The efficiency of subglacial drainage is known to have a profound influence on subglacial deformation and glacier dynamics with, in particular, high meltwater contents and/or pressures aiding glacier motion. The complex sequence of Middle Pleistocene tills and glacial outwash sediments exposed along the north Norfolk coast (Eastern England) were deposited in the ice-marginal zone of the British Ice Sheet and contain widespread evidence for subglacial deformation during repeated phases of ice advance and retreat. During a phase of easterly directed ice advance, the glacial and pre-glacial sequences were pervasively deformed leading to the development of a thick unit of glacitectonic mélange. Although the role of pressurised meltwater has been recognised in facilitating deformation and mélange formation, this paper provides evidence for the subsequent development of a channelised subglacial drainage system beneath this part of the British Ice Sheet filled by a complex assemblage of sands, gravels and mass flow deposits. The channels are relatively undeformed when compared to the host mélange, forming elongate, lenticular to U-shaped, flat-topped bodies (up to 20–30 m thick) located within the upper part of this highly deformed unit. This relatively stable channelised system led to an increase in the efficiency of subglacial drainage from beneath the British Ice Sheet and the collapse of the subglacial shear zone, potentially slowing or even arresting the easterly directed advance of the ice sheet.     

Biostratigraphic and aminostratigraphic constraints on the age of the Middle Pleistocene glacial succession in north Norfolk,UK

Considerable debate surrounds the age of the Middle Pleistocene glacial succession in East Anglia following some recent stratigraphical reinterpretations. Resolution of the stratigraphy here is important since it not only concerns the glacial history of the region but also has a bearing on our understanding of the earliest human occupation of north‐western Europe. The orthodox consensus that all the tills were emplaced during the Anglian (Marine Isotope Stage (MIS) 12) has recently been challenged by a view assigning each major till to a different glacial stage, before, during and after MIS 12. Between Trimingham and Sidestrand on the north Norfolk coast, datable organic sediments occur immediately below and above the glacial succession. The oldest glacial deposit (Happisburgh Till) directly overlies the ‘Sidestrand Unio‐bed’, here defined as the Sidestrand Hall Member of the Cromer Forest‐bed Formation. Dating of these sediments therefore has a bearing on the maximum age of the glacial sequence. This paper reviews the palaeobotany and describes the faunal assemblages recovered from the Sidestrand Unio‐bed, which accumulated in a fluvial environment in a fully temperate climate with regional deciduous woodland. There are indications from the ostracods for weakly brackish conditions. Significant differences are apparent between the Sidestrand assemblages and those from West Runton, the type site of the Cromerian Stage. These differences do not result from contrasting facies or taphonomy but reflect warmer palaeotemperatures at Sidestrand and a much younger age. This conclusion is suggested by the higher proportion of thermophiles at Sidestrand and the occurrence of a water vole with unrooted molars (Arvicola) rather than its ancestor Mimomys savini with rooted molars. Amino acid racemisation data also indicate that Sidestrand is significantly younger than West Runton. These data further highlight the stratigraphical complexity of the ‘Cromerian Complex’ and support the conventional view that the Happisburgh Till was emplaced during the Anglian rather than the recently advanced view that it dates from MIS 16. Moreover, new evidence from the Trimingham lake bed (Sidestrand Cliff Formation) above the youngest glacial outwash sediments (Briton's Lane Formation) indicates that they also accumulated during a Middle Pleistocene interglacial – probably MIS 11. All of this evidence is consistent with a short chronology placing the glacial deposits within MIS 12, rather than invoking multiple episodes of glaciation envisaged in the ‘new glacial stratigraphy’ during MIS 16, 12, 10 and 6. Copyright © 2009 John Wiley & Sons, Ltd.     

Evidence from the Trent terrace archive, Lincolnshire, UK, for lowland glaciation of Britain during the Middle and Late Pleistocene

The late Middle Pleistocene fluvial terrace sequence of the lower Trent system, Lincolnshire (eastern England), provides an excellent record of environmental change, including evidence for the last two interglacial episodes. It also provides important stratigraphical evidence for the timing and extent of three separate glaciations. Two of these, the Anglian and Devensian, are well-established correlatives of Marine Isotope Stages (MIS) 12 and 2 respectively; the third is a hitherto un-named post-Anglian-pre-Devensian glaciation in eastern England that has been the subject of much previous speculation, but can now be attributed with some confidence to MIS 8. Crucially, the recognition of MIS 7 interglacial deposits within the Balderton-Southrey terrace of the proto-Trent indicates that the underlying Wragby Till, which is ascribed to this additional glaciation, was emplaced no later than MIS 8. The oldest terrace preserved within the lower Trent staircase, the Eagle Moor-Martin Terrace, is considered to be a complex glacial outwash terrace related to the Wragby Till glaciation. It is suggested that deposits representing MIS 11-9, which are conspicuously absent throughout the Trent system, were removed by this glaciation. This is a departure from previous interpretations, which have suggested MIS 10 or MIS 6 as the most likely stages in which an extensive post-Anglian-pre-Devensian lowland glaciation might have occurred in Britain. However, the widespread preservation of undisrupted post-MIS 8 fluvial sequences throughout the Trent valley and in neighbouring systems, within which MIS 7 interglacial deposits have now been recognized at a number of localities, indicates that ice sheets are unlikely to have advanced further into this catchment during MIS 6 than during the Devensian (MIS 2). Recognition of a British glaciation during MIS 8 corresponds with widespread evidence in Europe, which suggests that glacial deposits classified as ‘Saalian’ represent both MIS 8 and MIS 6; in many areas, distinguishing these remains controversial, as confident correlation with either stage is often only possible where glacial sediments interdigitate with well-constrained fluvial records.     

Early and Middle Pleistocene river systems in eastern England: evidence from Leet Hill,southern Norfolk,England

Pleistocene sediments at Leet Hill, southern Norfolk are examined in terms of their sedimentary structures, palaeocurrent indicators, clast and heavy mineral lithology and litho- and morphostratigraphic position. Colour of the quartzite and vein-quartz clasts is used to differentiate the Bytham and the Kesgrave sands and gravels, with the Bytham sands and gravels having a significantly higher proportion of coloured material. The Kirby Cane sands and gravels are the lower sedimentary unit and were deposited by the Bytham river, which drained a catchment extending into central England. At Leet Hill, erosion of the Kesgrave Sands and Gravels by the Bytham river has given the Kirby Cane sands and gravels a distinctive lithological assemblage. Trace clast lithologies suggest that the Kesgrave Sands and Gravels in the region of Leet Hill were deposited in a coastal location with an input from northern sources as well as southern and Welsh sources diagnostic of the Thames catchment. The glaciofluvial Leet Hill Sands and Gravels were deposited by outwash from the Anglian Scandinavian ice sheet. Initially the flow direction of the outwash was determined by the Bytham river valley, but this changed to a southerly direction once the valley had been infilled. This paper provides the first indication of the location of the boundary (Early Pleistocene coastline) between the fluvial Kesgrave Sands and Gravels and the marine equivalent reworked by coastal processes, and demonstrates the way the pre-glacial relief initially controlled patterns of glaciofluvial sedimentation during the early part of the Anglian glaciation. Copyright © 1999 John Wiley & Sons, Ltd.     

Pleistocene deposits at Stoke Goldington,in the valley of the Great Ouse,UK

At Stoke Goldington in the valley of the Great Ouse in Buckinghamshire a river terrace at a height of about 7 m above the floodplain is underlain by fluvial sediments representing climatic fluctuations in the late Middle Pleistocene. Near the base of the succession, at a level only 1 m above the modern floodplain, a fossil assemblage, including pollen, plant macrofossils, molluscs, insects and ostracods, provides evidence for the local development of herb-rich grassland under temperate climatic conditions. The fossil record, amino-acid racemisation ratios and uranium disequilibrium dating all suggest deposition of this material during Oxygen Isotope Stage 7. The deposits containing the temperate assemblage are immediately overlain by typical cold-climate gravels of the Great Ouse. These have been subjected to a later cut-and-fill episode, with the fill accumulating in cool climatic conditions. The cut-and-fill episode was succeeded by aggradation, forming the overlying terrace surface. Amino-acid racemisation ratios indicate that the fill was emplaced, and the terrace surface created, during or after Oxygen Isotope Stage 5. © 1996 John Wiley & Sons, Ltd.     

Marine Isotope Stage 7–6 transition age for beach sediments at Morston,north Norfolk,UK: implications for Pleistocene chronology,stratigraphy and tectonics

Optically stimulated luminescence age estimates for the Pleistocene beach at Morston, north Norfolk, UK, obtained by the single‐aliquot regenerative‐dose protocol, indicate a Marine Isotope Stage (MIS) 7–6 transition date. The view that the beach is of Ipswichian (MIS 5e) age, held virtually unanimously for the last 75 years, may now be discarded. The extant beach sequence lies up to ～5 m OD, yet global models suggest that MIS 7–6 sea levels were typically substantially below that of today. The explanation may lie with poorly understood regional tectonic movements. The MIS 7–6 date helps to constrain the ages of glacial deposits that bracket the beach sediments at Morston. The underlying Marly Drift till cannot be younger than MIS 8; this may also be true for the complex assemblage of glaciogenic landforms and sediments, including the Blakeney esker, in the adjacent lower Glaven valley. The well‐established Late Devensian (MIS 2) age of the Hunstanton Till is not compromised by the date of the Morston beach. There is no indication of a proposed Briton's Lane glaciation during MIS 6 times. Copyright © 2009 John Wiley & Sons, Ltd.     

Patterns of preglacial sedimentation and glaciotectonic deformation within early Middle Pleistocene sediments at Sidestrand, north Norfolk, UK

Middle Pleistocene preglacial and glacial sediments are described from Sidestrand in north Norfolk, UK. The sequence consists of estuarine and fluvial deposits of the Wroxham Crag and Cromer Forest-bed formations that were deposited by, and adjacent to, a major river system that drained northern and central England during the ‘Cromerian Complex’. These preglacial sediments were subsequently overridden and partially tectonised during a glaciation that deposited till of the Happisburgh Formation associated with the first lowland glaciation of eastern England. Detailed examination of the stratigraphy and structural evolution of the sequence reveals that glaciotectonic rafts of Sidestrand Unio Bed material, a regionally important biostratigraphic marker horizon, have been remobilised and partially mixed with other lithologies whilst being transported and emplaced further up-sequence by glaciotetconic processes. Caution should therefore be exercised when examining this deposit for biostratigraphic and palaeoenvironmental purposes to ensure that sampling is from in situ material.     

Cesi,an early Middle Pleistocene site in the Colfiorito Basin (Umbro-Marchean Apennine), central Italy

Near the village of Cesi, at the head of the Chienti River, in the Colfiorito Basin (Umbro-Marchean Apennines, central Italy), fluvio-lacustrine deposits have yielded mammal fossil remains. The results of a multidisciplinary investigation indicate that the vertebrate-bearing sediments date about 700 ka and accordingly provide a fossil assemblage for the Middle–Late Galerian. Palynological investigations carried out from sediments underlying the fossiliferous level suggest predominantly cold and dry conditions, whereas the fauna suggests a slight climatic amelioration towards cool and moist conditions in the uppermost part of the sequence. © 1997 John Wiley & Sons, Ltd.     

Re-evaluation of the Middle Pleistocene stratigraphy of Herefordshire,England

Lithostratigraphical analysis of remnants of high-level, poorly sorted gravel remnants in northeast Herefordshire has allowed the revision and expansion of the existing regional Middle Pleistocene stratigraphical sequence to incorporate two new formations. The oldest Pleistocene sediments in the region, the Humber Formation, represents part of a major, northerly derived, cold-stage fluvial system, which incorporated the ancestors of the rivers Lugg and Wye and tributaries of the Severn. The Risbury Formation consists of glacigenic sediments, which were deposited by a large ice-lobe emanating from a Welsh ice-cap. The Risbury Formation is correlated with glacigenic deposits in the Cradley Brook Valley on the west side of the Malvern Hills, which were formerly ascribed to a pre-Hoxnian, Severn Valley ice-sheet. © 1998 John Wiley & Sons, Ltd.     

New insights into the deformation of a Middle Pleistocene glaciotectonised sequence in Norfolk,England through magnetic and structural analysis

North Norfolk is a classic area for the study of glacial sediments with a complex glaciotectonic deformational history, but the processes leading to the formation of some structures can be ambiguous. Anisotropy of magnetic susceptibility (AMS) analyses, providing quantitative fabric data, have been combined with the analysis of visible structures and applied to the Bacton Green Till Member, exposed at Bacton, Norfolk. Thermomagnetic curves, low temperature susceptibility and acquisition of isothermal remanent magnetism (IRM) reveal that the magnetic mineralogy is dominated by paramagnetic phases. The magnetic foliation is parallel to fold axial planes and weakly inclined to bedding, whilst the magnetic lineation is orientated parallel to stretching, indicated by the presence of stretching lineations and the trend of sheath folds. Variations in the orientation of the magnetic lineation suggest that the Bacton section has been subject to polyphase deformation. After subaqueous deposition, the sequence was overridden by ice and glaciotectonically deformed which involved stretching initially north–south, then east–west. These results show that AMS can be used to detect strain in three dimensions through a glaciotectonite where paramagnetic mineralogy is dominant. This approach therefore provides further support to the use of AMS as a fast, objective and accurate method of examining strain within deformed glacial sediments.     

江西九江中更新世红土物质来源研究

华南地区广泛分布中更新世红土。目前, 对其物质来源尚有争议。九江红土剖面的沉积时代已得到很好限定, 同时由于其沉积连续、地层出露较好, 是开展中更新世红土物质来源研究的理想剖面。通过对九江中更新世红土2件碎屑锆石样品的分析, 共获得177颗谐和锆石U-Pb年龄, 主要峰值集中在新元古代(816 Ma、801 Ma和991 Ma)、古元古代(2019 Ma、2022 Ma和2481 Ma)和新太古代(2502 Ma), 并具有不显著的中生代峰值(135 Ma)。将其与潜在远源和近源物源区的锆石U-Pb年龄组成进行对比, 结果发现中国北方戈壁、沙漠和黄土高原、塔里木盆地、华北平原并不是九江中更新世红土的主要源区。庐山北麓早更新世发育的洪积扇为九江中更新世红土发育提供了充足物质。九江中更新世红土和九江晚更新世黄土的碎屑锆石U-Pb年龄组成存在明显差别, 后者主要来自长江河漫滩的碎屑物质。不同的气候条件主导了九江地区红土和黄土的发育, 二者都受控于青藏高原构造隆升产生的环境变化。     

Pollen record from Colle Curti and Cesi: Early and Middle Pleistocene mammal sites in the Umbro–Marchean Apennine Mountains (central Italy)

The palynological record from the Colle Curti and Cesi continental deposits has been examined in order to identify the main palaeofloristic and vegetational changes between 0.99 and 0.6–0.7 Ma. These data show a progressive increase in aridity, as well as a progressive decrease in temperature, which are associated with the transition in dominance from the 41 to 100 ka cyclicity in the Milankovitch orbital record during the Middle Pleistocene. The disappearance of Tsuga, recorded during the lower part of the Brunhes Chron, also has been related to a shift in global aridity. During the successive open vegetational phases (glacials), Chenopodiaceae and Artemisia progressively increase, whereas Cyperaceae decrease. Forest phases (interglacials) are successively dominated by Tsuga, Abies with Picea and, finally, Pinus; but all lack significant expansion of broad‐leaved deciduous taxa. Palynological and sedimentological data, in addition to taphonomic interpretations, demonstrate the occurrence of several hiatuses in the lower parts of the interglacials. These hiatuses are considered to represent the palaeoenvironmental response to climatic changes affecting local sedimentological and geomorphological conditions. Copyright © 2000 John Wiley & Sons, Ltd.     

Re‐interpretation of the Meikirch pollen record,Swiss Alpine Foreland,and implications for Middle Pleistocene chronostratigraphy

The Meikirch drilling site in the Swiss Midlands north of Bern is re‐interpreted using a combination of sedimentological logging, pollen analyses and luminescence dating. The sedimentary sequence comprises about 70 m of lacustrine deposits, overlain by about 39 m of coarse glacial outwash interpreted to represent at least two independent ice advances. Pollen analyses of the apparently complete limnic sequence reveal a basal late glacial period followed by three warm phases that are interrupted by two stadial periods (Meikirch complex). The warm periods were previously correlated with the Holsteinian and Eemian Interglacials. According to luminescence dating, and with consideration of evidence for Middle Pleistocene climate patterns at other central European sites, a correlation of the Meikirch complex with marine isotope stage (MIS) 7 is now proposed. If this correlation is correct, it implies the presence of three intervals with interglacial character during MIS 7. However, the late Middle Pleistocene vegetational features of the Meikirch complex show significant differences when compared with the pollen record from the Velay region, central France. Possible explanations for this discrepancy are distinct Middle Pleistocene patterns of atmospheric circulation over central Europe and a different distribution of vegetation refugia compared to the Eemian Interglacial and the Holocene. Copyright © 2005 John Wiley & Sons, Ltd.     

Early and Middle Pleistocene vegetation history of the Médoc region,southwest France

Pleistocene deposits, together with their pollen, plant macrofossil, foraminiferal, dinoflagellate and coleopteran remains, from five sites along the Atlantic coast of the Médoc Peninsula are described and discussed. Sediments making up the Négade Formation are shown to have been laid down under either estuarine or lagoonal conditions when closed Quercus–Pinus‐Tsuga canadensis regional woodland existed. Comparison with plant records from The Netherlands indicates that these deposits are most likely attributable to either the Early Pleistocene Bavel Interglacial (marine oxygen isotope stage (MIS) 31), or an interglacial of the Waalian (MIS 37–49) or Tiglian (MIS 63–79). In addition, clays assigned to the Argiles du Gurp sensu stricto, were similarly deposited in either an estuary or lagoon, which subsequently was cut off from the sea. A freshwater lake with vegetation dominated by Azolla filiculoides then developed. This was succeeded by reedswamp and an organic mud (termed Lignite in the corresponding French stratigraphical records) formed. Regional Quercus–Abies woodland was replaced by one with Pinus dominant and Pterocarya a minor component. Comparison with plant records from France and other parts of Europe suggest that the clays and organic mud might be correlated with the Holsteinian (Praclaux) Interglacial (MIS 11c). Copyright © 2003 John Wiley & Sons, Ltd.     

A new chronological framework for Middle and Upper Pleistocene landscape evolution in the Sussex/Hampshire Coastal Corridor, UK

The unique Middle and Late Pleistocene sedimentary record preserved along the Sussex/Hampshire Coastal Corridor between Romsey and Brighton contains a wealth of deposits including highstand marine sediments associated with a variety of different aged beaches, fluvial sediments associated with rivers crossing the coastal plain and cold stage deposits accumulating above the marine and fluvial sediments. Although quarrying activity has been extensive across much of the area it has been undertaken in flooded workings due to the high level of the watertable. Consequently little is known in detail about the sequences except where they outcrop on the foreshore around the coast. This paper examines recent work from the lower coastal plain using a multi-disciplinary approach these deposits to elucidate the age of the sequences and their associated environments of deposition.OSL dates from two of the beaches, the Aldingbourne and Brighton/Norton Beaches, place both within MIS 7. Although these OSL dates cannot differentiate between sub-stages within MIS 7, coupling these results with inferences from local geography, lithology and contained microfossils it is clear that the beaches belong to two different phases within MIS 7. These two beaches are clearly divided by a major phase of erosion and downcutting associated with a fall in sea-level. Fluvial sediments from Solent Terrace 2 and Arun Terrace 4 also date within MIS 7 and are tentatively ascribed to the downcutting event between the beaches. Together this information allows us to propose, for the first time, a robust independently dated framework for the lower parts of the coastal plain integrating for the first time the marine and terrestrial record.     

Middle and late Pleistocene glaciations in the Campo Felice Basin (central Apennines, Italy)

The present paper refers to research conducted in the tectonic-karst depression of Campo Felice in the central Apennines (Italy), in which glacial, alluvial and lacustrine sediments have been preserved. Stratigraphic interpretations of sediments underlying the Campo Felice Plain are based on evidence obtained from nine continuous-core boreholes. The boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces. Each cycle is interpreted as an initial response to a mainly warm stage, characterized by low-energy alluvial and colluvial deposition, pedogenesis, and limited episodes of marsh formation. In turn, a mainly cold stage follows during which a lake formed, and glaciers developed and expanded, leading to deposition of glacial and fluvioglacial deposits. The chronological framework is established by eleven accelerator mass spectrometer ¹⁴C ages and three ³⁹Ar-⁴⁰Ar ages on leucites from interbedded tephra layers. These age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2, 3-4, 6, 10 and 14.     

河北阳原盆地中更新世湖相地层顶部文石的发现及其科学意义

位于河北省西北部的阳原盆地在第四纪期间长期被泥河湾古湖所占据,堆积了巨厚的第四纪河湖相地层,其中夹有多层化学沉积。文中对广泛分布于盆地西端河湖相地层顶部的白色化学沉积进行了深入研究,通过野外调查和年代测试、电子显微镜扫描观察、X射线粉晶衍射、常量和微量元素分析,以及硅藻和介形类化石鉴定等一系列实验手段,确认北梁地区地层中的灰白色化学沉积主要由文石组成,其年龄大致在270 ka前后,属中更新世晚期,是在当时比较温干的气候环境下,湖泊逐渐萎缩、湖水不断咸化、文石类矿物大量析出的结果。该地区的泥河湾古湖于中更新世晚期消亡。本研究首次发现了中更新世晚期的化学沉积,在时代上明显区别于以前发现的晚更新世晚期化学沉积。该化学沉积的发现为探讨泥河湾古湖消亡过程和原因提供了直接的沉积学证据,对于重建我国北方中更新世晚期的古环境也具有重要的科学意义。