G. R. Coope

The Devensian (Weichselian) Lateglacial palaeoenvironmental record from Gransmoor, East Yorkshire, England: A contribution to the ‘North Atlantic seaboard programme’ of IGCP-253, ‘Termination of the Pleistocene’

Abstract Palynological and coleopteran data are described from a section through Late Devensian (Weichselian) deposits at Gransmoor, East Yorkshire, England. The pollen evidence shows that, following an initial open-habitat episode, first Juniperus scrub and later Betula woodland became established in the area during the Lateglacial Interstadial. This woodland was replaced during the Loch Lomond (Younger Dryas) Stadial by a predominatly herbaceous flora with arctic/alpine, steppe and halophytic elements. The coleopteran evidence indicates a similar local environment and that the thermal maximum of the Interstadial, when mean July temperatures may well have exceeded 18°C, occurred prior to the deposition of the earliest polleniferous sediments. By the time of the Juniperus expansion, summer temperatures had fallen by 2–4°C to levels comparable with those of the present day. A further temperature decline followed the expansion of Betula during the later Interstadial and another fall occurred at the Lateglacial Interstadial/Loch Lomond Stadial boundary. During the Loch Lomond Stadial mean July temperatures of 9–11°C are implied, with winter temperatures as low as −15 to −20°C. Collectively the evidence reemphasises the point that for the first 1000 years or so of the Lateglacial Interstadial, there was a disequilibrium between the palynological and coleopteran records in terms of climatic signal. During the later Interstadial, however, a closer relationship is apparent between both proxy data sources. Of particular significance in this respect is the fluctuation in reconstructed summer and winter temperatures, and a rise and subsequent fall in Betula pollen frequencies. This may be the correlative of one of the pre-Younger Dryas climatic oscillations recorded in other proxy data sources including palynological records from Britain and eastern Canada, oxygen isotope traces from Swiss lake sediments, isotopic and electrical conductivity profiles from the Greenland ice sheet, and diatom and foraminiferal records in cores from the Norwegian Sea and the North Atlantic Ocean.

Devensian Lateglacial environmental changes in Britain: a multi-proxy environmental record from Llanilid, South Wales, UK

Abstract A multi-proxy environmental record for the Devensian (Weichselian) Lateglacial and early Holocene periods, which includes pollen, plant macrofossil, coleopteran, geochemical and stable-isotope data, is described from a site at Llanilid, South Wales, UK. The geochronology of the sequence is derived from two age–depth models which show a broad measure of agreement over much of the profile. This data set provides the basis for a detailed reconstruction of changing environmental conditions in western Britain during the transition from the Last Cold Stage to the present (Holocene) interglacial (ca 15,000–10,000xa0calxa0yr BP). Two marked cooling episodes are recorded during the course of the Lateglacial Interstadial (Greenland Interstadial 1), with mean July temperatures falling by more than 5°C from a maximum of around 20°C during the early Interstadial, and by a further 4–5°C around 13,100xa0calxa0yr BP. The initial drop in temperature led to a reduction in Juniperus scrub, while the second, and more abrupt temperature decline resulted in a significant contraction in areas of Betula woodland. A relatively slight and short-lived warming during the later Interstadial enabled tree birch to expand once again. Mean July temperatures of 10–11°C characterised the Loch Lomond/Younger Dryas Stadial (Greenland Stadial 1) between ca 12,600 and 11,400xa0calxa0yr BP, during which time a scrub tundra with Betula , Salix and a range of open-habitat taxa became established locally. The onset of the Holocene Interglacial at ca 11,400xa0calxa0yr BP is marked by an abrupt temperature rise of the order of 9°C, and by the rapid expansion of Betula woodland. The Llanilid palaeoclimate record is similar to that from the Gransmoor site in northeast England, and also to the climatic sequence inferred from the GRIP ice core, particularly during the later part of the Lateglacial Interstadial (ca 14,000–12,600xa0calxa0yr BP), during the Loch Lomond/Younger Dryas Stadial and in the early Holocene. The Llanilid chronology is less secure during the early part of the Lateglacial Interstadial (pre-14,000xa0calxa0yr BP), but it is possible that warming may have begun earlier in this part of western Britain than in Greenland.

A Late Pleistocene insect fauna from Chelford, Cheshire

Insect remains, chiefly of beetles, have been obtained from a Late Pleistocene organic mud which was interbedded within the Middle Sands at Chelford, Cheshire. These deposits represent an interstadial during an early phase of the Last (Würm) Glaciation. The insects were usually preserved as fragments embedded in felted vegetable matter but associated pieces representing almost complete animals were occasionally found. Remarkably good preservation was not uncommon and structural colours, scales and hairs were often retained. It has been possible to match most of the remains with modern species but a few specimens, though very distinctive, have so far defied all attempts at specific identification and may represent extinct forms. A faunal list is provided and the relative abundance of each species is given. From a consideration of the modern environmental requirements of this fauna it has been possible to deduce much of the ecology of the district at the time of the deposition of the organic mud. It is suggested that this deposit was laid down in a stagnant, acid water pool choked with vegetable matter and partially overgrown by Sphagnum. The dominant trees in the district were conifers and birches with willows in the marshy ground near to the pool. The climate was cold but by no means extremely severe and it is suggested that the nearest equivalent may be found to-day in Finland between latitudes 60° and 64°. These deductions are discussed in the light of palaeobotanical evidence provided by the organic mud. The geological significance of the deposit is briefly discussed.

The Upper Pleistocene deposits at Cassington, near Oxford, England

For much of the Middle and all of the Upper Pleistocene the Upper Thames valley has remained outside the limit of ice advance. The main agents of landform evolution have been the River Thames and its tributaries, which have cut down episodically and in so doing have abandoned a series of river terraces. This study reports the findings of an investigation into exposures in the deposits underlying the Floodplain Terrace at Cassington, near Oxford, England. The sequence exposed reveals a stratigraphy of basal, predominantly fine-grained, lithofacies overlain by coarser gravel lithofacies. The fluvial architecture of these deposits indicates a major change in fluvial style from a low-energy (meandering) to a high energy (braided) channel system. The flora and fauna from the lower fine-grained lithofacies display a marked change from temperate at the base, to colder conditions towards the top, indicating a close association between deteriorating climate and changing fluvial depositional style. Amino acid and luminescence geochronology from the basal fine-grained lithofacies suggest correlation with Oxygen isotope Stage 5 and hence it is argued that the major environmental change recorded at the site relates to the Oxygen-Isotope Stage 5-4 transition. Deposition of much of the overlying gravel sequence probably occurred during Oxygen isotope Stage 4, suggesting that the latter half of the Devensian may be less significant, in terms of fluvial landscape evolution in the Upper Thames valley, than was believed previously

A late Middle Pleistocene temperate–periglacial–temperate sequence (Oxygen Isotope Stages 7–5e) near Marsworth, Buckinghamshire, UK

Abstract River-channel and colluvial deposits, near Marsworth, Buckinghamshire, record a temperate-periglacial-temperate sequence during the late Middle Pleistocene. The deposits of a lower channel contain tufa clasts bearing leaf impressions that include Acer sp., and Sorbus aucuparia and containing temperate arboreal pollen attributed to ash-dominated woodland. The tufa probably formed at the mouth of a limestone spring before being redeposited in a small river whose deposits contain plant remains, Mollusca, Coleoptera, Ostracoda and vertebrate bones of temperate affinities. The sediments, sedimentary structures and limited biological remains above the Lower Channel deposits indicate that fluvial deposition preceded climatic cooling into periglacial conditions. Fluvial deposition recurred during a later temperate episode, as shown by the mammalian bone assemblage in stratigraphically higher channel deposits. The Upper Channel deposits are confidently attributed to Oxygen Isotope Sub-Stage 5e (Ipswichian) on the basis of their vertebrate remains. However, the age of the Lower Channel deposits is less clear. The mammalian and coleopteran remains in the Lower Channel strongly suggest correlation with Oxygen Isotope Stage 7 on the basis of their similarities to other sites whose stratigraphy is better known and the clear difference of the Lower Channel assemblage from well-established faunas of Ipswichian or any other age. By contrast, U–Th dating of the tufa clasts suggests an age post 160xa0ka BP, while Aile/Ile ratios on Mollusca point to an Ipswichian age and younger. Four ways of interpreting this age discrepancy are considered, the preferred one correlating the Lower Channel deposits with Oxygen Isotope Stage 7.

Tibetan Species of Dung Beetle from Late Pleistocene Deposits in England

A LARGE and distinctive species of the dung beetle Aphodius that is clearly not a member of the present day European fauna has frequently been found in deposits in England that date from the middle of the Last Glaciation1,2. Although at times very abundant (from one peaty lens in a gravel pit near Dorchester on Thames, fossils of at least 150 individuals were obtained) the identity of this species has up to now remained a mystery. The fact that the skeletal elements were to a large extent disarticulated made the use of keys to identification impossible and, with more than five hundred described species of Aphodius in the Palaearctic region alone, it would have been imprudent to describe the fossils as a new, possibly extinct, species. Thus in accounts of fossil assemblages of Coleoptera, this species has been given the non-committal designation of Aphodius sp. A of Upton Warren after the site in Worcestershire1 where it was first found. The solution to the identity of this species was both unexpected and dramatic.

Sedimentology, palaeoecology and geochronology of Last Interglacial deposits from Deeping St James, Lincolnshire, England

Pollen, plant macrofossil, molluscan and coleopteran data from organic muds below the low terrace of the River Welland at Deeping St James, Lincolnshire indicate deposition in the mixed oak forest phase of a Late Pleistocene interglacial. Coleopteran and molluscan data suggest summer temperatures up to 4°C warmer than at present in eastern England, and plant macrofossil material suggests a climate more continental than that of Britain in the Holocene. No direct analogue of this biota, however, exists currently in Europe. Biostratigraphical indications from the pollen coleoptera and Mollusca suggest an age in the Ipswichian Interglacial. Thermoluminescence dates between 120 ka and 75 ka and amino-acid ratios with a mean of 0.11 show that deposition of the sediments took place during Oxygen Isotope Stage 5. This accurate dating of a partial Ipswichian succession allows discussion of the ages of a number of other interglacial sites in eastern England of assumed Ipswichian age. Copyright

Regression coefficients of thermal gradients in northwestern Europe during the last glacial-Holocene transition using beetle MCR data.

Palaeotemperature estimates obtained from 74 sites in northern Europe, and collectively spanning approximately the last 45 000 yr (radiocarbon time-scale), have been compiled as a major component o ...

Middle Pleistocene deposits at Frog Hall Pit, Stretton‐on‐Dunsmore, Warwickshire, English Midlands, and their implications for the age of the type Wolstonian

Organic sediment from Frog Hall Pit, near Coventry, has produced pollen, plant macrofossil, insect, ostracod and molluscan data indicative of the early part of a temperate episode in the Middle Pleistocene. The regional stratigraphy and clast lithological characteristics of the gravels underlying the temperate deposits show that the whole sequence at the site post-dates the major glaciation (the Wolstonian sensu Mitchell et al., 1973) of the Midlands. Amino-acid D/L ratios from molluscan shells give mean values of 0.24, which is consistent with an age in Oxygen Isotope Stageu20099 and comparable with those from the Hoxnian Interglacial of East Anglia. This age-estimate for the Frog Hall organic deposit places a minimum age on the Wolstonian Glaciation of the Midlands in Oxygen Isotope Stageu200910, and therefore close in time to the Anglian (Oxygen Isotope Stageu200912) Cold Stage.

Middle Devensian deposits beneath the ‘Upper Floodplain‘ terrace of the River Thames at Kempton Park, Sunbury, England

Gravel pit sections in the ‘Upper Floodplain’ terrace exposed current-bedded gravel and sand containing a grey clayey silt lens. This silt has yielded fossil macroscopic plant remains, molluscs, ostracods and insects. Sedimentological and palaeontological results indicate that the silts were deposited in a slowly flowing river channel. The gravel and sand accumulated under cool, seasonally contrasting climatic conditions and represent braided stream deposits. A new lithostratigraphical unit, the Kempton Park Gravel, is proposed and its relation to the local terrace stratigraphy of the Thames is discussed. A radio-carbon date of 35,230 ± 185 BP indicates that the Kempton Park Gravel unit aggraded during the Middle Devensian substage.