G.R. Coope

Temperature gradients in northern Europe during the last glacial-Holocene transition (14-9 14C kyr BP) interpreted from coleopteran assemblages.

Late-glacial and early Holocene climatic conditions have been reconstructed for northern Europe using the mutual climatic range (MCR) palaeoclimate method based on fossil coleopteran assemblages. Altogether, beetle faunas from 77 sites have been analysed ranging from Ireland in the west to Poland and Finland in the east, and MCR estimates calculated. The results are plotted on 16 maps, each representative of a selected time-slice covering the period from 14.5 14C kyr BP to 9.0 14C kyr BP. Eight of the maps show the MCR estimates of Tmax (mean temperature of the warmest month) derived from each site for which data are available, while the remainder show estimated Tmax isotherms interpolated from these values. It can be demonstrated that at times the thermal climate was fairly uniform throughout the study area, whereas at others temperature gradients were much steeper than they are in the region today. There also appears to be a distinct contrast between cold periods, when contours trended NW–SE, and warmer periods, when contours trend W–E or even NE–SW. The pattern of climatic changes that emerges is shown to be very different from the traditional view that has been used up to now as a template for classifying Late-glacial climatic events on a wide, even global, scale. The suddenness and intensity of changes in the thermal climate may have been partially responsible for an apparent lack of equilibrium between the flora and fauna of the time and the physical environment in which they lived.

Weichselian Late Pleniglacial and Late-glacial depositional environments, Coleoptera and periglacial climatic records from central Poland (Belchatów).

Environmental conditions during the Weichselian have been studied at the Belchatow brown coal pit in central Poland. Palaeoclimate has been reconstructed by a multiproxy approach based on sedimentary environments, periglacial structures and Coleoptera remains. The Weichselian Middle to Late Pleniglacial sequence reveals a change from lacustrine to fluvial deposition. During the Late Pleniglacial, deposition by ephemeral streams with relatively stable channels was abruptly replaced by braided-river deposition. An increased aridity and the disappearance of the vegetation are held reponsible for this change in river style. The increase of aridity in the second part of the Late Pleniglacial has been inferred from the absence of organic material in the braided deposits and the extension of aeolian environments at the expense of the braided environment. A return towards wetter conditions during the Late-glacial has been inferred from lake marl deposition and local fluvial reworking of dunes. Special attention has been given to the climate reconstruction of the early Late Pleniglacial (26–24 ka). Permafrost conditions during this period, in combination with local strong relief and intensive slope processes, resulted in rapid aggradation by ephemeral streams with relatively stable channels. The climate during the early Late Pleniglacial was extremely harsh. The habitat was in many ways analogous to the true tundra of the present-day Arctic. The periglacial features indicate a mean annual air temperature lower than −4°C. The coleopteran assemblage from Belchatow is one of the most cold-adapted faunas so far recorded from Europe. The mean temperatures of the warmest and coldest months were respectively 8°C and −27°C. It is concluded that a strong temperature decline, especially of the winter temperature, occurred at the transition from the Middle to the Late Pleniglacial. At the onset of the Late-glacial Younger Dryas period a cooling of the climate has been inferred from the presence of small ice-wedge casts at the base of overlying dune sands. A mean annual air temperature between −2 and −5°C is postulated.

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.

Climatic and environmental reconstructions based on fossil assemblages from middle devensian (Weichselian) deposits of the river Thames at south kensington, central London, UK

Abstract Fossiliferous silts within the Late Pleistocene Kempton Park Gravel, of the River Thames Valley, were exposed in 1980 during foundation works for the Ismaili Centre in South Kensington, London. The results of a multidisciplinary study of the geomorphology, sediments, fossil plants, vertebrates, molluscs, ostracods and insects are reported. The silts were deposited under two distinct climatic regimes; a lower unit accumulated when the climate was arctic and an upper when the temperatures were at least as warm as those of the present day. Both these units occupy the same channel system and are separated from one another by less than a metre of sediment, implying that the climatic change was probably sudden and intense. The strongest evidence for this climatic difference comes from a study of the Coleoptera, which show an almost complete replacement of the arctic element in the fauna by a suite of temperate species. Palaeotemperature reconstructions using the Mutual Climatic Range method, based on the coleopteran assemblages from the lower unit, suggest that the mean temperature of the warmest month was 9±2 °C and that of the coldest month −22±10 °C. For the upper unit the mean temperature of the warmest month had risen to about 17 °C and that of the coldest month to about −4 °C. The episode represented by the lower unit, with its arctic climate, had not previously been recognized in the Thames Valley. The fauna from the upper, temperate, unit is very similar to that from other sites in the Kempton Park Gravel, such as that from Isleworth, 10 km upriver, which, like the upper unit at the Ismaili Centre, was characterized by the virtual absence of trees. It would appear that in such cases this treelessness does not indicate cold conditions, equivalent to those of the modern tundra, but may instead result from a combination of ecological and temporal factors. The value of multidisciplinary studies in reaching such conclusions is emphasized. The temperate episode described here is correlated with the thermal maximum at the early part of the Upton Warren Interstadial Complex. An earlier suggestion, based on amino acid epimerization ratios, that the Upton Warren Interstadial correlates with Oxygen Isotope Sub-stage 5a is not supported by the data, which show no evidence of the forested environments that characterized this period in both Britain and the adjacent Continent. It is thought that the temperate deposits at the Ismaili Centre belong to the Middle (Pleniglacial), rather than the Early, Devensian (Weichselian) and are equivalent to Oxygen Isotope Stage 3.

Biostratigraphical distinction of interglacial coleopteran assemblages from southern Britain attributed to Oxygen Isotope Stages 5e and 7

Abstract Beetle assemblages are described from 14 interglacial sites in southern England, all of which post-date the Hoxnian Interglacial (in the broad sense) and which can safely be attributed to Oxygen Isotope Stages 5e and 7. The beetle faunas from these interglacial deposits are large and complex and together include at least 387 named species many of which are no longer found living in the British Isles. Almost all of the latter have modern geographical distributions exclusively to the south of Britain and some are predominantly Mediterranean. A few have their nearest relatives living today in North Africa or as far away as northern India. Some of these temperate beetle assemblages are remarkably similar to one another especially in their inclusion of diagnostic exotic species. Others, though indicative of a temperate climate, exhibit consistent differences so that the 14 assemblages clearly divide themselves into two groups; Group (a) and Group (b), based on differences in their species composition and abundance. Group (a) beetle faunas, from seven sites, may be termed “classic” Ipswichian (Eemian) since they closely resemble the assemblage from the type site at Bobbitshole near Ipswich and have unimpeachable stratigraphical contexts. All of these faunas can with confidence be attributed to an early phase of Oxygen Isotope Sub-Stage 5e. Group (b) beetle faunas, also from seven sites, are very different in their specific composition and are more of a puzzle because they include some fossil assemblages from deposits that have, in the past, been attributed to the latter part of the Ipswichian Interglacial and others that are undoubtedly from stratigraphical deposits that are earlier than the Ipswichian and which have been correlated with Oxygen Isotope Stage 7. It is with the deposits yielding Group (b) faunas that the greatest controversy arises. On-line appendix available at http://www.elsevier.com/locate/quascirev

Age-estimate evidence for Middle-Late Pleistocene aggradation of River Nene 1st Terrace deposits at Whittlesey, eastern England

At Whittlesey, eastern England, Pleistocene interglacial sediments (unit G3) deposited in marine oxygen isotope stage (MIS) 7 appear to be truncated by a sequence comprising: (i) a limestone-rich gravel containing organic mud beds (unit F1); (ii) vertically aggrading gravel beds with sand-clay-lined bases (unit F2); and (iii) interbedded sands and gravels (units F4–F6) with associated overbank deposits (unit G4). Preliminary investigations of the floral and faunal assemblages of the organic muds were consistent in providing evidence for deposition under cool conditions. This apparent single cool/cold-phase sequence therefore could have been deposited in either MIS 6 or MIS 5d−2. The presence of sand beds in units F5, F6 and G4 and of molluscs in the organic mud beds of unit F1 provided the opportunity for obtaining age estimates using optically stimulated luminescence (OSL) and amino acid racemization (AAR). Rather than a single cool/cold-phase sequence the age-estimate data revealed multiphase aggradation, with the AAR data indicating the possibility that the organic muds in unit F1 were deposited earlier in MIS 7 than the interglacial deposits of unit G3. Therefore, the succession could be: unit F1 was truncated initially by unit G3, with unit F2 subsequently incising both unit F1 and unit G3. The OSL age estimates indicate that units F5, F6 and G4 are Early to Middle Devensian in age (MIS 5d-2), and therefore unit F2 was deposited sometime between late MIS 7 and MIS 5d. This paper has demonstrated the utility of using dual age-estimate techniques in dating complex fluvial sequences. Furthermore, the organic mud beds of unit F1 could provide important new information on the complex character of the MIS 7 interglacial. In addition, the OSL data and the fluvial style recorded by units F4–F6 and G4 allow comparisons to be made with recent investigations of nearby Devensian deposits.

Palaeontology and biostratigraphy of Middle Pleistocene river sediment in the Mathon Member, at Mathon, Herefordshire, England

Organic silts and sands filling a channel underlying glacial deposits have beendiscovered in a gravel pit near Mathon, Herefordshire. These organic deposits, termed the Brays Bed, occur at the base of the Mathon Valley Formation and have yielded abundant fossils of plants (pollen and macroscopic remains) and insects (Coleoptera and Trichoptera). Palaeoecological analyses of these remains show that the deposit was largely made up of flood debris washed into an abandoned channel on the floodplain of an ancient river, thus sampling the biota from the surrounding landscape. The vegetation was chiefly made up of coniferous forest including Pinus, Picea and Larix with rarer broad-leaved trees. The insects comprise a community dependent on these trees, as well as a rich variety of species that inhabited the main river. Quantified estimates of the thermal climate using the Mutual Climatic Range method and based on the coleopteran assemblage, show that, at the time of deposition, conditions were not much different from those of the present day. A few species suggest that it might have been slightly more continental, than today. Precipitation must have been adequate to support a vigorous flow in the main river throughout the year. Correlation has been made on palaeontological grounds with four pre-Anglian deposits, two in Warwickshire, English Midlands, one in Lincolnshire and a fourth in Essex. Tentative links are also established with early Middle Pleistocene temperate deposits at Happisburgh, Norfolk, and the Boxgrove complex, which are included within the Cromerian Complex Stage (‘Cromerian Interglacial IV’), the latter assigned to Marine Isotope Stage 13.

Reappraisal of Middle Pleistocene fluvial deposits near Brandon, Warwickshire and their significance for the Wolston glacial sequence

Recent exposures at Pools Farm Pit, Brandon have allowed a reinvestigation of strat-igraphic relationships critical to the debate concerning the status of the Wolstonian Stage of the British Pleistocene. Central to the original case for maintaining the type site of the Wolstonian Stage at Wolston, Warwickshire is the acceptance that the fluviatile Baginton Formation (Shotton’s Baginton-Lillington Gravel and Baginton Sand) forms, together with the glacigenic Wolston Formation, a series of sediments (Shotton’s Wolston Series) deposited during a single post-Hoxnian (i.e. post-oxygen isotope stage 9) glacial stage. Evidence presented in this paper suggests this interpretation is no longer tenable. The sediments of the Baginton Formation exposed at Pools Farm Pit record the facies changes identified by Shotton in 1968. A predominantly gravel unit, the Brandon Gravels (Baginton Gravel Member), is overlain by a sandy unit, the Brandon Sands (Baginton Sand Member), the bounding surface being erosional. Two newly exposed fine-grained organic channel fills are described. The Brandon Lower Organic Sands and Silts lie within the Brandon Gravels and contain a temperate coleopteran fauna and a boreal forest flora. Correlation of these organic deposits on fauna1 grounds with the nearby site of Waverley Wood suggests a correlation with oxygen isotope stage 15. The Upper Organic Silts and Clays lie within the Brandon Sands and contain a cold climate fauna and flora. The Brandon Sands are overlain locally by the Brandon Upper Sands and Gravels which are correlated with the Ailstone Member of the Avon Valley Formation (stage 6). The younger Avon Valley Formation is known to extend back to at least stage 9 and therefore given that the Wolston Formation is younger than the Baginton Formation as indicated by a borehole nearby, it could represent any of the cold stages 10, 12 or 14. However, stage 12, the Anglian, remains the most likely attribution.

The palaeoecology and age of peat at Fliquet Bay, Jersey, Channel Islands

The compacted remains of a Carex swamp peat were sampled for pollen and coleoptera. Analyses of these revealed evidence of open habitat conditions and implies increasing cold and a withdrawal of the sea during the deposition of the peat. The age of the peat is uncertain but its relationship to nearby head, together with palaeoecological evidence for a deteriorating climate, suggest that it may have affinity with the early part of the Devensian glacial stage.