MIS 5a Research Articles

Late quaternary sea level changes of Gabes coastal plain and shelf: Identification of the MIS 5c and MIS 5a onshore highstands, southern Mediterranean

The continental shelf of the Gulf of Gabes is outlined, during the MIS 5c and MIS 5a onshore highstands, by the genesis of forced regressive beach ridges situated respectively at –19 m b.s.l/100 ka and –8 m b.s.l/80 ka. This area, considered as a stable domain since at least the last 130 ka (Bouaziz et al. 2003), is a particular zone for the reconstruction of the late quaternary sea-level changes in the region. Shuttle Radar Topography Mission (SRTM) data and field observations are highlighted to deduce interaction between hydrodynamic factors and antecedent topography. Variations in geomorphology were attributed to geological inheritance. Petrography and sedimentary facies of the submerged coastal ridges reveal that the palaeocoastal morphology was more agitated than today and the fluvial discharges are consistent. Actual morphologic trend deduced from different environment coasts (sandy coasts, sea cliffs and tidal flat) is marked by accumulation of marine sands and progradation.

Paleoenvironments in the Fram Strait during Marine Isotope Stages 2–6 based on planktonic paleobiological and stable-isotope proxies and ice-rafted debris

Two sediment cores from the Knipovich Ridge in the Fram Strait have been studied to examine paleoceanographic and climatic changes in the Polar North Atlantic during the late Middle and Late Pleistocene. As inferred from the data on foraminifers, nannofossils, diatoms, IRD, oxygen isotope values, and AMS 14C ages, the recovered deposits span the interval of MIS 2–6. Several beds marked by a high productivity of microplankton and often by a great IRD content are recorded in MIS 2, MIS 5a, 5c, 5e, and MIS 6 suggesting a repeated occurrence of seasonally ice-free waters and strong meridional circulation in the eastern Fram Strait. The planktonic foraminifers Globigerinoides ruber, Globorotalia scitula, G. crassaformis, and pink-colored Globigerina rubescens, exotic for this latitude, were identified in three points of the section. A hiatus in one of the cores studied was revealed from comparison of IRD variations and the occurrence of Pullenia bulloides.

The glacial history of the southern Svartenhuk Halvø, West Greenland

This paper presents a new, detailed geomorphological and sedimentological appraisal of the southern Svartenhuk Halvo, a remote area of West Greenland that has only been subjected to limited geomorphological and sedimentological research. Despite this, it is of importance as several studies have suggested it remained an ice-free enclave during the Last Glacial Maximum. This previous work, based on biostratigraphic and chronological evidence, has provided evidence for the ‘Svartenhuk Marine Event’, a period of ice free conditions and marine deposition into a higher than present relative sea-level during the previous interglacial (MIS 5a–e). This has been correlated to other interglacial deposits in West Greenland. New geomorphological and sedimentological investigations from this study present compelling arguments for the glaciation of southern Svartenhuk Halvo by valley glaciers and mountain ice caps, questioning the status of this peninsula as an ice-free enclave. Ice directional indicators and clast lithological results suggest ice covering Svartenhuk Halvo was sourced from the higher altitude interior of the peninsula and expanded to the present coastline. In a number of valleys, sedimentological evidence points to at least two glacial advances with subglacial till production through the reworking of glaciomarine sediments, and ice contact and glacier-fed delta deposition during phases of ice retreat. The geomorphological and sedimentological context of the sediments (Gilbert type deltas), coupled with evidence for eskers and kettled/pitted delta surfaces, suggests these features formed under glacial and not interglacial conditions. This is supported by new radiocarbon dates which suggest outlet glacier advance and retreat across the area towards the end of MIS 3 and possibly into the Early Holocene. Svartenhuk Halvo was not overrun by the main Greenland Ice Sheet during the last glacial cycle, but the development of an independent ice cap and local outlet glaciers across this region may have been instrumental in determining the dynamic evolution of the Uummannaq ice stream onset zone during the last glacial cycle.

Climatic implications of the Quaternary fluvial tufa record in the NE Iberian Peninsula over the last 500 ka

The drainage area of the Iberian Ranges (NE Spain) houses one of the most extensive Quaternary fluvial tufaceous records in Europe. In this study, tufa deposits in the Añamaza, Mesa, Piedra and Ebrón river valleys were mapped, stratigraphically described and chronologically referenced from U/Th disequilibrium series, amino acid racemization and radiocarbon methods. Tufa deposits accumulated in cascades, barrage-cascades and related damming areas developed in stepped fluvial systems. The maximum frequency of tufa deposition was identified at 120ka (Marine Oxygen Isotope Stage [MIS] 5e), 102ka (MIS 5c), 85ka (~MIS 5a) and 7ka (MIS 1), probably under warmer and wetter conditions than today. Additional phases of tufa deposition appear at ~353ka (~end of MIS 11), 258–180ka (MIS 7) and 171–154ka (MIS 6). Although most tufa deposition episodes are clearly correlated with interstadial periods, the occurrence of tufa deposits during the penultimate glaciation (MIS 6) is remarkable, indicating that the onset of this stage was climatically favourable in the Iberian Peninsula. Biostatic conditions and the dynamics of karstic systems regulating tufa deposition seem to be sensitive to the precipitation regime, controlled by shifts in the position of North Atlantic atmospheric belts, and summer insolation, regulated by orbital forcing.

The Middle Paleolithic occupations of Üçağızlı II Cave (Hatay, Turkey): Geoarcheological and archeological perspectives

The site of Üçağızlı II is located in a partially collapsed cave on the Mediterranean coast of the Hatay region, South Central Turkey. A small intact chamber (chamber D) preserves a sequence of Middle Paleolithic deposits nearly 2m thick. Test excavations at the site in 2005 and 2007 produced large assemblages of artifacts, vertebrate and shellfish remains. The entire sequence formed during the Upper Pleistocene, subsequent to MIS 5a. Faunal and lithic assemblages are comparatively homogeneous, consistent with the inference that the deposits formed under relatively constant environmental conditions. Micromorphological analyses reveal an abundance of combustion features and products, although the visibility of the features is locally compromised by local, small-scale bioturbation. There is evidence that the ways fires were created and maintained changed along with the intensity of occupation. Lithic assemblages most closely resemble other Middle Paleolithic assemblages from the northern Levant but there are inconsistencies with the accepted pattern of technological change over time in the Levantine Mousterian more broadly. Faunal and lithic evidence indicate that the intensity and duration of occupational events declined over time at Üçağızlı II. While there are many parallels in raw material economy with the early Upper Paleolithic of the nearby Üçağızlı I site, the Middle Paleolithic hominins may have used the coastal landscape in a different way from later Upper Paleolithic groups.

Increased aridity in southwestern Africa during the warmest periods of the last interglacial

Abstract. Terrestrial and marine climatic tracers from marine core MD96-2098 were used to reconstruct glacial–interglacial climate variability in southwestern Africa between 194 and 24 thousand years before present. The pollen record documented three pronounced expansions of Nama-karoo and fine-leaved savanna during the last interglacial (Marine Isotopic Stage 5 – MIS 5). These Nama-karoo and fine-leaved savanna expansions were linked to increased aridity during the three warmest substadials of MIS 5. Enhanced aridity potentially resulted from a combination of reduced Benguela Upwelling, expanded subtropical high-pressure cells, and reduced austral-summer precipitation due to a northward shift of the Intertropical Convergence Zone. Decreased austral-winter precipitation was likely linked to a southern displacement of the westerlies. In contrast, during glacial isotopic stages MIS 6, 4 and 3, fynbos expanded at the expense of Nama-karoo and fine-leaved savanna indicating a relative increase in precipitation probably concentrated during the austral winter months. Our record also suggested that warm–cold or cold–warm transitions between isotopic stages and substages were punctuated by short increases in humidity. Increased aridity during MIS 5e, 5c and 5a warm substages coincided with minima in both precessional index and global ice volume. On the other hand, austral-winter precipitation increases were associated with precession maxima at the time of well-developed Northern Hemisphere ice caps.

Fluctuations of Mediterranean Outflow Water circulation in the Gulf of Cadiz during MIS 5 to 7: Evidence from benthic foraminiferal assemblage and stable isotope records

We studied variations in benthic foraminiferal assemblages and δ13C for the last 225kyr at IODP site U1387 which is currently bathed by upper core of the Mediterranean Outflow Water (MOW). The MOW paleocirculation and sea-floor environment (oxygen level, trophic condition, bottom current strength) have been inferred from faunal composition; species diversity, abundances of selected index species/groups, microhabitat preferences combined with δ13C record of the epifaunal Cibicidoides pachyderma. The faunal and isotope records indicate relatively better ventilation at sea-floor and low trophic condition during MIS 1, 5 and 7 possibly due to increased influence of upper MOW in the Gulf of Cadiz. Our multi-proxy record reflects significant and rapid changes during cold (stadial) and warm (interstadial) phases within the interglacials MIS 5 and 7 and at Termination II. The faunal and isotope records reveal strong MOW flow and better ventilated, oligotrophic bottom-water conditions during stadials MIS 5b, 5d, 7b and 7d. The study further demonstrates weakened MOW intensity associated with poor ventilation and increased trophic level at sea-floor during interstadials MIS 5a, 5e, 7a and 7c. MOW flow was relatively sluggish at Termination II, followed by its strengthening at the end of MIS 5e. The chronology of these events suggests that periods of weakened MOW correlate with sapropel layers of the Mediterranean Sea, implying strong coupling between glacial–interglacial climate and MOW circulation in the Gulf of Cadiz.

High-resolution OSL dating of a late Quaternary sequence from Xingkai Lake (NE Asia): Chronological challenge of the “MIS 3a Mega-paleolake” hypothesis in China

In this paper a combined OSL (49 samples) and 14C (14 samples) dating study was conducted on a sediment core from Xingkai Lake, NE Asia. A single-aliquot regenerative-dose protocol was used to determine the equivalent dose (De) of the extracted fine-grained (FG) quartz fraction; the suitability of the measurement procedure was confirmed by a set of luminescence tests (e.g., preheat plateau and dose recovery measurements). In addition, a post-IR infrared stimulated luminescence protocol at 290 °C (pIRIR290) was applied to the polymineral FG fraction of seven samples. Our results can be summarized as follows: (1) The uppermost sample was dated to ∼110 a, indicating that the OSL signal of FG quartz has been well bleached. This has been further confirmed by the consistency of OSL ages and pIRIR290 ages within <80 ka. The resulting OSL ages generally increased with depth, and the lowermost samples of core XK08 reached back to the last interglacial, although the pIRIR290 dating suggested that the quartz OSL ages likely begin to be underestimated beyond 80 ka; (2) The comparison of OSL and 14C ages suggested that the radiocarbon dating technique may significantly underestimate the age of sediments for samples older than 30 cal ka BP (corresponding to ∼25 14C ka BP), and thus it is necessary to pay attention when using such old 14C dates for paleoclimatic/archaeological interpretation; (3) This study challenges the radiocarbon-based chronology of the “MIS 3a Mega-paleolake” hypothesis, which had been reiterated for many years and extensively reported across northern and western China; and (4) The current high-resolution OSL dating record (one-age/5–10 cm) showed clear sedimentation rate changes down the core. The identified variations in the sedimentation processes at the orbital timescale may be related to regional/global climatic changes during the past 130 ka, and the high sedimentation rate during the last ∼0.4 ka has probably been caused by intensified human activities in the Xingkai Lake catchment.

Cosmogenic Be and OSL Dating of Marine Terraces Along the Central- East Coast of Korea: Spatio-Temporal Variations in Uplift Rates

We report the abandonment age of the Jeongdongjin (JDJ) coastal terrace that lies at 65 m a.s.l. The age of the JDJ terrace surface has yet to be equivocally constrained because of its antiquity (>MIS 5), challenging the application of conventional radiocarbon and optically stimulated luminescence (OSL) dating techniques. The reliability of applied indirect age constraints on the sediments by amino-acid racemization and tephra chronology is debated. We present the first application of cosmogenic surface exposure dating to constrain the age of the old terrace in Korea. We dated four samples from the paleo shore platform surface using cosmogenic 10 Be surface exposure dating techniques. The analyses yielded exposure ages ranging from 240 to 170 kyr and likely correspond to the penultimate interglacial period (MIS 7). Sandy beach sediments overlying marine terraces at nearby Anin (~23 m a.s.l.) and Ayajin (~17 m a.s.l.) were dated by OSL. OSL dating of terrace beach sand in two separate areas yielded ages between 129-117 and 70-66 kyr, interpreted MIS 5e and MIS 5a, respectively. Combining the exposure ages and the heights of terraces corrected for paleo sea level, we obtain uplift rates of 353 for JDJ, 159 for Anin, and 238 mm/kyr for Ayajin. The results indicate spatio-temporal variations in the rate of surface uplift along the east coast of Korea during the late Quaternary. Furthermore, the west and east coasts of central Korea experienced different uplift histories during the late Quaternary, possibly resulting from the effects of different tectonic regimes.

Climate and vegetation since the Last Interglacial (MIS 5e) in a putative glacial refugium, northern Idaho, USA

There are very few terrestrial sediment records from North America that contain a nearly continuous sequence spanning from the Last Interglacial period to the present. We present stratigraphic records of pollen and several other proxies from a Carex-dominated wetland, Star Meadows, located 140 km south of the maximum extent of the Cordilleran Ice Sheet and near the current southern extent of interior mesic forests in northern Idaho. Many species in this region are disjunct by 160 km of arid steppe and dry forest from their more extensive distribution along the Pacific Northwest coast and may have survived in an interior refugium. The chronology for the upper 251 cm was determined by six radiocarbon dates and one tephra deposit, and the age of the remainder of the core (251–809 cm) was estimated by correlation with SPECMAP δ18O. Fluctuating water levels were inferred from alternating peat, biogenic silica, and aquatic pollen types. During MIS 5e the region was warmer and drier than today and was dominated by Pinus (likely Pinus contorta) mixed conifer forest surrounding a Carex meadow. A cool-moist climate (MIS 5b–5d) soon developed, and the site was inundated with deep water. Pollen indicated wetland vegetation (Betula glandulosa, Typhaceae, and Salix) developed around a lake with a Pseudotsuga/Larix and Picea forest on the surrounding slopes. During MIS 5a, a warmer climate supported a Pseudotsuga/Larix, Abies, and Picea forest on the surrounding hillsides and a Carex-dominated environment within a dry meadow. From MIS 4 to MIS 3, a cool and wet Pinus and Picea forest predominated. Water levels rose, enabling Nuphar to persist within a perennial lake while a sedge fen established along the lake margin. As climate transitioned into MIS 2, a cooler and drier climate supported a Pinus and Picea subalpine parkland, though water levels remained high enough to support Nuphar. During the Last Glacial Maximum the sediment was mainly silt and clay with high Artemisia and very poor pollen preservation. Glaciers descended to 500 m elevation above Star Meadows in adjacent drainages suggesting a periglacial environment occurred at the site. Lake level decreased through the Pleistocene–Holocene transition (ca. 11.7 ka) and the site returned to a sedge peatland surrounded by an open Pinus forest. The most striking vegetation change occurred in the middle to late Holocene with the first occurrence and then later dominance of Cupressaceae pollen, most likely Thuja plicata, which is a dominant species in modern interior mesic forests. The late Holocene vegetation was uniquely mesic in the context of the last 120,000 years, casting doubt on this region serving as a glacial refugium.

Cova del Rinoceront (Castelldefels, Barcelona): a terrestrial record for the Last Interglacial period (MIS 5) in the Mediterranean coast of the Iberian Peninsula

The Cova del Rinoceront, a site in NE Iberia, contains a thick sedimentary fill preserving a faunal archive from the penultimate glacial and the the last interglacial periods. Layers I to III have been dated to between 74 and 147 ka, coinciding with MIS 5a to 5e, a period poorly represented in the Mediterranean terrestrial record. The results from Cova del Rinoceront are of broader interest for the reconstruction of ecological dynamics during warm stages and the understanding of the evolution and geographical variation of several taxa. The palaeoecological evidence suggests a landscape dominated by mixed wooded vegetation with mild climatic conditions, slightly more humid than today. Several vertebrate taxa, including Haploidoceros mediterraneus, Stephanorhinus hundsheimensis and Glis glis, are documented for the first time in the early Upper Pleistocene of Europe, showing that these species persisted across the region for longer than previously thought. In addition, the recovery of a small lithic assemblage indicates human presence in the surroundings of the site. The 11 m-thick stratigraphic section also provides an ideal setting in which to compare several geochronological methods. U–Th dating of the flowstones that cap the deposit, of speleothems formed along the cave walls, and of speleothems buried by the deposit at different elevations provides minimum and maximum ages of 74 and 175 ka, respectively, for the accumulation. The ages obtained by luminescence, electron spin resonance (ESR), amino acid racemisation (AAR), palaeomagnetism and U-series dating of bone are in good agreement with each other and are stratigraphically consistent. This well-dated faunal succession presents a unique opportunity to assess changes in the Pleistocene fauna of the Mediterranean coast over an interval of more than 100 ka.

A review of New Zealand palaeoclimate from the Last Interglacial to the global Last Glacial Maximum

Results from terrestrial and marine palaeoclimate proxies are integrated to reconstruct palaeoclimate variations in New Zealand from the Last Interglacial to the global Last Glacial Maximum (gLGM). By combining data from 21 speleothems we have constructed composite O–C stable isotope sequences from 0 to 88.5 ka BP and from 107.8 to 128.2 ka BP. The gaps in the sequence (a 19.3 ka break in coverage in MIS 5b/c and a 2.97 ka gap in MIS 5a) preclude the construct of a continuous record; so data were referenced to a common scale by normalising individual records (subtracting means and dividing by standard deviation). Overlapping records were then merged chronologically. These records were compared to integrated summer insolation for 45°S and to terrestrial and marine environmental proxies available for the New Zealand region.The MIS 5e thermal maximum in New Zealand was around 128–122 kiloyears BP (ka BP) and therefore similar in timing to the Last Interglacial in Australia, southern Europe and Greenland. Temperatures in parts of the North Island may have been 2°–3 °C warmer than present and the sea rose 3–6 m above modern level. In MIS 5d and 5b cool conditions with glacial advances occurred in the South Island, but from about 87 to 73 ka in MIS 5a warmth within 2 °C of present characterised most of the interstadial (locally termed the Otamangakau Interstadial).Conditions then cooled rapidly and culminated in a MIS 4 glacial advance that was the greatest of the New Zealand Last Glacial Cycle (nzLGM). The climate was cool to cold and while wet in westerly windward locations may have been dry in the east. Combined Australian and New Zealand evidence suggests glacial culmination around 67–62 ka. This regional LGM coincided with severe cooling in Europe.During MIS 3 conditions were very variable. The climate in eastern North Island (Hawke Bay and the Bay of Plenty) at the start of MIS 3 was similar to the Holocene, and the period 61–43 ka was relatively mild overall and is termed the Aurora Interstadial, although it contained a short interval of mountain glacier expansion around 49–47 ka. After 43 ka conditions cooled again with a glacial advance from 42 to 38 ka, before a return to milder but still cool conditions during the Moerangi Interstadial from 37 to 31 ka. After this conditions deteriorated at the lead in to the gLGM. The maximum glacial advance occurred in late MIS 3 between 31 and 29 ka. The glacial onset was abrupt with Te Anau Glacier in Fiordland, one of the largest in the Southern Alps, taking only about 2000 years to achieve its maximum gLGM depth, probably because conditions were wet as well as cold. But stable isotope data suggest that the climate then became drier, while remaining cold, and the glacier progressively ablated such that its surface had lowered 390 m by the start of MIS 2 and by >600 m by ca 18 ka.The gLGM maximum in New Zealand may have led the terrestrial (ice-sheet) LGM in the Northern Hemisphere by a few thousand years, possibly because alpine glaciers respond more rapidly to climate change than continental ice sheets. The culmination of the gLGM in NZ occurred in MIS 3 about 12 000 years before global ice volume reached its peak as determined by the marine stable isotope record (the marine gLGM). By the time global ice volume was at a maximum (19 ka) glaciers had almost disappeared from major Fiordland valleys in New Zealand. Whereas polar ice sheet records have revealed a “bi-polar see-saw”, this is not so evident in the mid-latitudes, because some temperate zone inter-hemispheric climate events coincide closely in time. Perhaps the see-saw effect diminishes with distance from the poles?

Quaternary climate change and Heinrich events in the southern Balkans: Lake Prespa diatom palaeolimnology from the last interglacial to present

Lake Prespa, in the Balkans, contains an important palaeo-archive in a key location for understanding Quaternary climate variability in the transition between Mediterranean and central European climate zones. Previous palaeoenvironmental research on sediment cores indicates that the lake is highly sensitive to climate change and that diatoms are likely to be strong palaeohydrological proxies. Here, we present new results from diatom analysis of a ca. 91 ka sequence, core Co1215, which spans the time from the end of the last interglacial to the present. Fluctuations in the diatom data were driven primarily by changes in lake level, as a function of shifts in moisture availability. Warmer interglacial (MIS 5, MIS 1) and interstadial (MIS 3) phases exhibit higher lake levels in spite of enhanced evaporative concentration, underlining the importance of changes in precipitation regimes over time. Low lake levels during glacial phases indicate extreme aridity, common to all Mediterranean lakes. Evidence for fluctuations in trophic status is linked, in part, to lake-level change, but also reflects nutrient enrichment from catchment processes. MIS 5a is characterized by the highest lake productivity in the sequence, but low lake levels, which are ascribed primarily to very low precipitation. On a suborbital timescale, the diatoms provide evidence for correlation to the millennial-scale variability recorded in the Greenland oxygen isotope records and clearly reflect the impact of the Heinrich H6, H5 and H3–1 ice-rafting events, suggesting the dominant influence of North Atlantic forcing in this region. Although the highest-amplitude shift in the diatom assemblages occurs during the time of H4 (40–38 ka), it may be superimposed upon the impact of the 39.28 cal ka BP Campanian Ignimbrite volcanic eruption. Diatoms from Lake Prespa core Co1215 display the first strong evidence for the impact of Italian volcanic activity on lacustrine biota in this region. Results emphasize the complexity of diatom response thresholds in different studies across the region. In the case of Lake Prespa, the results highlight the important role of precipitation for maintaining the hydrological balance of the lake, and indirectly, its biodiversity.

Middle Pleistocene stratigraphy of the deposits in Za Hájovnou Cave (Javoříčko Karst, northern Moravia, Czech Republic)

Middle Pleistocene stratigraphy of the deposits in Za Hájovnou Cave (Javoříčko Karst, northern Moravia, Czech Republic)

수렴단층노두 해안단구 퇴적층의 OSL 연대에 대한 재고찰: 단일입자 OSL 연대측정 연구

이 논문에서는 경주시 양남면에 분포하는 해발고도 약 45 m의 수렴단층 노두 해안단구 퇴적층의 형성시기를 추정하기 위하여, 퇴적층을 구성하고 있는 석영에 대한 단일입자 OSL(Single Grain Optically Stimulated Luminescence) 연대측정을 실시하였다. 실험에 사용된 총 1200개의 석영입자 중, 93개의 입자가 연대측정에 적합한 OSL 신호특성을 보였으며, 이들의 등가선량은 50-610 Gy까지 넓은 분포를 보인다. 이 자료를 중심연대모델(Central Age Model)과 최소연대모델(Minimum Age Model)을 이용하여 분석하면, 각각 <TEX>$83{\pm}4ka$</TEX>와 <TEX>$60^{+3}{_{-7}}ka$</TEX>의 연대가 도출되지만, 이들 연대는 MIS 5a시기로 보고된 기존의 제2해안단구의 OSL 연대와 층서적으로 불일치한다. 단일입자 OSL 분석결과들을 혼합연대모델(Finite Mixture Model)에 적용하면, 분석된 입자들 중 <TEX>$6{\pm}4%$</TEX>의 석영입자가 MIS 7의 퇴적시기 <TEX>$194{\pm}24ka$</TEX>)를 지시함을 알 수 있다. 결론적으로, 수렴단층 노두 해안단구 퇴적층이 MIS 7 시기에 형성되었을 가능성을 배제할 수 없으며, 이 퇴적층은 일반적으로 적용되는 다입자 OSL(multiple grain OSL) 연대측정법을 적용하기에 적합하지 않은 시료로 판단된다. In this paper, we report new OSL ages of the marine terrace sediments at Suryum fault site, using single grains of quartz, and briefly discuss their chronological implications on the timing of terrace formation along the southeastern coast of Korea. Of 1200 grains measured, 93 quartz grains were found to have OSL properties suitable for dating, the equivalent dose (<TEX>$D_e$</TEX>) values of which varied significantly, ranging from 50 Gy to 610 Gy with the overdispersion of <TEX>$30{\pm}4%$</TEX>. Applied to the Central Age Model (CAM) and Minimum Age Model (MAM), these quartz grains showed the OSL ages of <TEX>$83{\pm}4ka$</TEX> and <TEX>$60^{+3}{_{-7}}ka$</TEX>, respectively, both of which are stratigraphically inconsistent with the previously reported OSL ages of lower <TEX>$2^{nd}$</TEX> terrace (MIS 5a; ~80 ka). However, Finite Mixture Model (FMM) revealed that a small fraction of the measured quartz grains (<TEX>$6{\pm}4%$</TEX>) were of the ages (<TEX>$194{\pm}24ka$</TEX>) corresponding to MIS 7. Conclusively, based on single grain OSL ages, it would be prudent not to exclude the possibility that the marine terrace sediments at Suryum fault site have formed during MIS 7. Further, our single grain OSL ages imply that multiple grain(single aliquot) OSL dating methods are not applicable to the marine sediments at Suryum fault site.

Biogeography of Pleistocene conifer species from the Ziegler Reservoir fossil site, Snowmass Village, Colorado

Pleistocene biogeography of conifer species is poorly known in much of western North America. We conducted morphological studies on 201 conifer cones and cone fragments recovered from Pleistocene sediments at the Ziegler Reservoir fossil site (2705m) near Snowmass Village, Colorado. The basin, formed ~155–130ka, contains fossil-bearing lacustrine, palustrine, and colluvial sediments spanning approximately 85ka. Using a suite of morphological characters, particularly cone-scale bracts, we differentiated species of Abies, Picea, and Pseudotsuga. All fossil Abies specimens were assignable based on bract morphology to Abies concolor, which is currently absent from central Colorado (nearest populations are 160km southwest of the site). A. concolor occurs only in sediments of MIS 5d and 5c. Pseudotsuga menziesii and Picea engelmannii cones occurred in sediments corresponding to MIS 5e, 5d, 5c, and 5a. A fourth conifer species, occurring in sediments of MIS 5e, 5d, 5c, and 5a, is difficult to assign to any extant species. Bract morphology is similar to Picea pungens, which grows near the site today, but scale morphology is unlike P. pungens. These fossils may represent ancestral P. pungens, an extinct variant, or an extinct sister species.

Last interglacial plant macrofossils and climates from Ziegler Reservoir, Snowmass Village, Colorado, USA

Ninety plant macrofossil taxa from the Ziegler Reservoir fossil site near Snowmass Village, Colorado, record environmental changes at high elevation (2705masl) in the Rocky Mountains during the Last Interglacial Period. Present-day vegetation is aspen forest (Populus tremuloides) intermixed with species of higher (Picea, Abies) and lower (Artemisia, Quercus) elevations. Stratigraphic units 4–13 contain montane forest taxa found near the site today and several species that today generally live at lower elevations within (Abies concolor, Lycopus americanus) and outside Colorado (Najas flexilis). These data suggest near-modern climatic conditions, with slightly warmer summer and winter temperatures. This montane forest period was succeeded by a shorter treeless interval (Unit 14) representing colder and/or drier conditions. In units 15–16, conifer trees reoccur but deciduous and herb taxa are lacking, suggesting a return to warmer conditions, although cooler than during the earlier forest period. Comparison of these inferred paleoclimatic changes with the site's geochronologic framework indicates that the lower interval of sustained warmth correlates with late MIS 6–early 5b (~138–94ka), the cold interval with MIS 5b (~94–87ka), and the uppermost cool assemblages with MIS 5a (~87–77ka).

Palynological record of tropical rain forest vegetation and sea level fluctuations since 140 ka from sediment core, south-eastern Arabian Sea

Palyno-chronological study of a 552cm deep sediment core from the south-eastern Arabian Sea covers a time span of ~140ka. The age estimate is based on oxygen isotopic data of planktic foraminifera. Six zones were identified on the basis of palynology covering partially MIS-6 and MIS-5 to MIS-1 (Marine Isotopic Stages). The interglacial period (MIS-5) shows high rate of sedimentation corresponding to high percentage of terrestrial rain forest pollen. The palynological study reveals highstand and intense rain forest vegetation during MIS 5a which corresponds to the similar earlier records of estuarine ecosystem on land in Kerala. The relative sea level rise and fall since ~140ka have been inferred through quantitative estimate of marine versus terrestrial palynomorphs. The terrigenous non-pollen forms comprised abundant Neogene extinct nanoplanktons (Discoaster spp.) until MIS-3 which was transported from the Varkala Formation (highlands of the Kerala coast). The pollen assemblage is comparable to the present day flora in Kerala except Ongokea gore which is now present in South Africa and therefore, the provenance of pollen recorded in the studied core is Western Ghats of India. High percentage of planktic foraminifera and dinoflagellate cysts throughout the core indicates high productivity that suggests upwelling induced by seasonal reversals in the monsoon winds even during the glacial periods. Botryococcus remains and poaceous leaf cuticles dominated by the Pooideae group in the marine realm also point towards active winter monsoon. Considerable fragmentation of rain forest took place post 74ka and during the LGM as the sea retreated to its maximum which resulted into the vast exposure of land favoring the expanse of grassland with pockets of rain forest “plant refugia” on land. Neogene rain forest flora recorded earlier from the Varkala Formation and the present record of its existence since MIS-6 in the region provide an understanding that the monsoon circulation over southern India was similar since the Middle Miocene Climate Optimum and the flora in the South-Western Ghats is a fossil ecosystem and a relic of the Tertiary period.

An investigation of palaeodietary variability in European Pleistocene canids

Temporal and interspecific dietary variability were investigated in three canid taxa, Canis lupus, Canis mosbachensis and Canis etruscus, across a range of British and mainland European wolf assemblages from the Early Pleistocene to Recent periods. Using established cranio-dental indicators to reveal dietary specialisations towards bone eating, flesh slicing, and non-flesh food crushing, inferences were made concerning the proportions of flesh to non-flesh foods in the diet, and hence the level of carnivory adopted by each taxon. Significant temporal differences were found in the diet and frequency of tooth wear of C. lupus from MIS 3, 5a and 7 in Britain. Relative body size comparisons based on lower carnassial length also revealed variation in body size for the Pleistocene age groups, correlating with differences in diet. Stepwise Discriminant Function Analyses revealed large-bodied MIS 5a C. lupus to be hypercarnivorous and specialised in fast flesh slicing and to some extent bone consumption, whereas relatively smaller-bodied MIS 3 and 7 C. lupus were both less carnivorous and more specialised in crushing non-meat foods. Modern wolves from central Sweden are smaller than those of MIS 5a and hypercarnivorous, although with greater specialisation towards crushing of non-meat foods. Temporal variations in diet were related to changes in prey diversity, competition from other carnivores, openness of the environment, and ultimately climate, and reflect the cranio-dental plasticity of C. lupus. In contrast, no temporal differences in diet were found in age groups of C. mosbachensis and C. etruscus, which may relate to more stable overall conditions in comparison to the later Pleistocene. The cranio-dental characteristics of the smaller-bodied mesocarnivore C. etruscus indicate adaptations to non-meat food crushing, whereas in the similarly small C. mosbachensis, enhanced flesh slicing capabilities and reduced crushing abilities indicate that it was more carnivorous than C. etruscus. C. etruscus and C. mosbachensis were both more specialised than C. lupus.

Chronology of Quaternary coastal aeolianite deposition and the drowned shorelines of southwestern Western Australia – a reappraisal

Aeolianite successions of low-gradient continental margins commonly show complex records of coastal dune deposition linked to a wide range of sea-level positions and climatic periods of the middle and late Pleistocene, recording both regional and broader-scale drivers of sediment production, coastal dune development and landform preservation. To better characterise the general pattern of sedimentation that occurs over Quaternary glacial–interglacial cycles on low-gradient, temperate carbonate continental shelves we examine the morphology, stratigraphy and age of aeolianite deposits in the Perth region, Western Australia. This includes an analysis of well-defined drowned coastal landforms preserved on the adjacent shelf. New and previously published optical ages provide a preliminary timeframe for the deposition of aeolianite in the Perth region and on Rottnest Island, 17 km offshore. An extensive aeolianite ridge near Perth, representing a former barrier, has Optically Stimulated Luminesence (OSL) ages that range from 120 ± 12 to 103 ± 10 ka (MIS 5e–5a in the context of associated age uncertainties). OSL ages for an exposure in the same ridge 2.5 km inland, record the onlap of much older aeolianite, OSL age 415 ± 70 ka, by shell-rich estuarine beds, OSL age 290 ± 30 ka. A further 5.5 km inland from the coast, two thick aeolianite units, separated by a well-developed palaeosol, have stratigraphically consistent OSL ages of 310 ± 30 and 155 ± 20 ka. In contrast, aeolianite units that form the northern coast of Rottnest Island have OSL ages of 77 ± 12 ka and 27 ± 5 ka. The new OSL ages and previously reported TL and U/Th ages indicate that the bulk of the island comprises dunes deposited around the end of the Last Interglacial sensu lato (MIS 5a–4) and during the Last Glacial (MIS 4–2), accumulating over a Last Interglacial coral reef and basal calcarenite. Drowned barrier and dune landforms preserved on the adjacent continental shelf reveal that barriers were formed during periods of intermediate sea level (e.g. MIS 3) and significant dune mobility occurred when the shelf was subaerially exposed. The pattern of shelf sedimentation discernible in the Perth region – large-scale coastal carbonate dune deposition during periods of high and intermediate sea level and reactivation during glacial lowstands – is largely consistent with published stratigraphic and age data for large-scale aeolianite deposits on other low-gradient carbonate shelves. Based on these data, a general model is proposed for the cycle of Quaternary sedimentation and landform evolution that occurs on these shelves, which are dynamic sedimentary environments with coastal landforms and sedimentary successions that are very sensitive to erosion and sediment reworking.