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Bahia state is widely known for the presence of fossiliferous deposits of Late Pleistocene – early Holocene. Although most studies in the state have been carried out on cave environments, studies concerning natural tank deposits have been expanded in the last few years, particularly in other states of Northeast Brazil. Therefore, the present work aims to study two new natural tanks: “Lagoa das Abelhas” and “Lagoa do Rancho”, in Guanambi municipality, south-central Bahia, Brazil. The identified taxa include representatives of Xenarthra ( Eremotherium laurillardi , cf. Glossotherium sp., Pachyarmatherium brasiliense , Glyptodontinae, Propraopus sulcatus , Pampatherium humboldti , and Holmesina paulacoutoi ), Notoungulata (Toxodontidae), Proboscidea, Perissodactyla ( Tapirus terrestris and Equus ( Amerhippus ) neogaeus ), and Cetartiodactyla (Camelidae). The taphonomic analysis allowed the fossiliferous deposit from Lagoa das Abelhas to be classified as an ex situ assemblage, while the Lagoa do Rancho deposit was interpreted as a peripheral assemblage. Based on its paleofaunal composition, the landscape of the Guanambi region would have comprised open areas with pastures and patches with arboreal elements. The 14 C radiocarbon dating results point to ages of 22,230 ± 55 years for the Lagoa das Abelhas and 16,020 ± 40 years for the Lagoa do Rancho tanks, indicating that the Guanambi paleofauna lived during the Last Glacial Maximum, in a drier phase of the Late Pleistocene. [ABSTRACT FROM AUTHOR]

The recognition of past climatic fluctuations in sedimentary sequences in central Mexico is relevant for understanding the forcing mechanisms and responses of climatic system in the northern American tropic. Moreover, in this active volcanic setting the sedimentary record preserves the history of past volcanic activity. Climatic and environmental variability has been documented for the last tenths of thousands of years from the upper lacustrine sediments in Chalco basin. A series of cores drilled down to 122 m depth in this basin offer a long, continuous and high resolution record of past climatic changes of the last ca. 150 kyr in this region. Here we present the detailed lithostratigraphy and some physical properties (magnetic susceptibility and density) of the master sequence. Sedimentary components and their abundance were identified and quantified in smear slides and direct core observations. Age model is based on 13 14 C and one 230 Th/U dates. Based on their facies association seven lithostratigraphic units were defined, which reflect the main stages of lake Chalco evolution. These phases closely match the marine isotopic stages. The data reveal that at the end of MIS6 Chalco was a relatively deep and stratified freshwater lake. During MIS5 the depositional environment fluctuated between low lake stands to marshy and marginal playa settings with sporadic flooding events, and severe arid periods resulted in aerial exposure of lake sediments. Low lake stands persisted during MIS4 and MIS3, with minor fluctuations towards slightly deeper phases. The Last Glacial Maximum (LGM) and the deglacial period (21-13 kyr) are characterized by intense volcanism. The early and mid-Holocene high calcareous content and alkaline-subsaline lake suggest dry conditions. The fluctuations of lake levels inferred provide the basis for future paleoclimatic works. [ABSTRACT FROM AUTHOR]

Sediment cores and seismic reflection data acquired from the eastern basin of Lake Kivu, Rwanda reveal extensive limnologic variations due to changes in regional climate and basin structure. The eastern basin of the lake contains a sedimentary wedge which is > 1.5 km in thickness on its western side, and basal sediments are estimated to be at least 1.5 million years old. Sediments are likely to be thicker and older than this in the northern, Congolese basin of the lake. Above the ∼300 m iosbath only a thin layer of Holocene sediments are observed indication that this may have been the lake’s high stand prior to that time. There are at least three erosional unconformities interpreted as desiccation or near-desiccation events which are estimated to have occurred at ∼475 ka, ∼100 ka, and ∼20 ka; the two most recent of these low stages likely developed during the African Megadrought and Last Glacial Maximum (LGM) periods. Following the LGM, the water levels rose to form a ∼100 m deep lake with its surface ∼370 m below the current lake level. The lake remained near that level for several thousand years and during this time the Virunga Volcanic Province expanded. At ∼12.2 ka a change to wetter climate conditions rapidly filled the lake to spill out of the Bukavu Bay basin southward toward Lake Tanganyika. Tephra sampled from the cores show that there have been at least 24 large local volcanic events since the early Holocene lake transgression. [ABSTRACT FROM AUTHOR]

Oil–water two-phase flow is the main fluid form in petroleum industry. Since it is associated with safety operation and economic benefit, the flow velocity needs to be measured accurately. A method based on continuous-wave ultrasonic Doppler and drift-flux model is presented to estimate the overall superficial flow velocity of oil–water two-phase flow. A theoretical correlation combining velocity profile and drift-flux model was proposed to relate the measured velocity in the sensing volume of the ultrasonic Doppler sensor with the overall superficial velocity of two-phase flow. The measuring system consists of two piezoceramics ultrasonic transducers with a center frequency of 1 MHz and a PXI-based data acquisition system. Dynamic experiments involving five typical flow patterns were performed in a horizontal Plexiglas pipe with an inner diameter of 50 mm. The results show that the measuring system and the proposed method estimate the overall superficial flow velocity with an average error of 2.27%. [ABSTRACT FROM AUTHOR]

The evolution of precipitation is a key question concerning future climatic changes, especially in regions like the Mediterranean area which are currently prone to droughts. The influence of atmospheric circulation changes (in the mid-latitude westerlies or in the strength of the subtropical subsidence), along with changes in local mechanisms generating precipitation (such as convection) make it difficult to predict precipitation changes confidently over this area. Understanding its governing mechanisms is crucial. A possible approach is to test our understanding on different documented past climatic contexts. This paper focuses on the Last Glacial Maximum period (LGM) over the western Mediterranean region and puts in perspective the available information inferred from paleo-climatic records and the outputs of nine global climate models. We first review the available information on LGM precipitation in this region and find that the environmental conditions prevailing at this period range from humid to semi-arid, depending on the proxies. Model outputs from the PMIP3-CMIP5 database also yield a wide range of mean annual responses in this area, from wetter to drier conditions with respect to the pre-industrial period. This variety of responses allows to investigate the mechanisms governing LGM precipitation in the western Mediterranean area. Over the Iberian Peninsula and northern Morocco, most models simulate a larger amount of LGM precipitation in winter w.r.t. the pre-industrial period. This feature is mainly due to the large-scale effect of the southward shift of the North Atlantic jet stream, which is closely associated with the surface air temperature changes over the northwestern North Atlantic. In summer, precipitation changes mainly result from convection and are correlated to local surface air temperature anomalies, highlighting the key role of local processes. These contrasted changes in winter and summer, linked to different mechanisms, could explain the range of various signals derived from paleo-climatic archives, especially if the climatic indicators are sensitive to seasonal precipitation. [ABSTRACT FROM AUTHOR]

To better understand glacial history and process in New England (northeastern United States), a mountainous area overrun by the Laurentide Ice Sheet, we measured three cosmogenic nuclides in nine upland samples. The concentrations of 10Be and 26Al in some samples collected near the summits of Katahdin (Maine) and Mount Washington and Little Haystack Mountain (New Hampshire) are 2-10 times higher than expected for a single exposure period, considering field evidence indicating that continental ice-covered all New England peaks during the Last Glacial Maximum. In-situ 14C exposure ages from the summits are much younger, suggesting that high-elevation sampling sites were ice-covered before and during the Last Glacial Maximum. Field and isotopic data are consistent with New England summits being covered in part by cold-based continental ice that did not erode much rock. The contrast in erosion rates between stable summits and deeply eroded valleys likely contributes to the development and maintenance of northern Appalachian topography. [ABSTRACT FROM AUTHOR]

The Last Glacial Maximum (LGM) is widely used to refer to the episode when global ice volume last reached its maximum and associated sea levels were at their lowest. However, the boundaries of the interval are ill-defined and the term and acronym have no formal stratigraphical basis. This is despite a previous proposal to define it as a chronozone in the marine records on the basis of oxygen isotopes and sea levels, spanning the interval 23–19 or 24–18 ka and centred on 21 ka. In terrestrial records the LGM is poorly represented since many sequences show a diachronous response to global climate changes during the last glacial cycle. For example, glaciers and ice sheets reached their maximum extents at widely differing times in different places. In fact, most terrestrial records display spatial variation in response to global climate fluctuations, and changes recorded on land are often diachronous, asynchronous or both, leading to difficulties in global correlation. However, variations in the global hydrological system during glacial cycles are recorded by atmospheric dust flux and this provides a signal of terrestrial changes. Whilst regional dust accumulation is recorded in loess deposits, global dust flux is best recorded in high-resolution polar ice-core records, providing an opportunity to define the LGM on land and establish a clear stratigraphical basis for its definition. On this basis, one option is to define the global LGM as an event between the top (end) of Greenland Interstadial 3 and the base (onset) of Greenland Interstadial 2, spanning the interval 27.540–23.340 ka (Greenland Stadial 3). This corresponds closely to the peak dust concentration in both the Greenland and Antarctic ice cores and to records of the global sea-level minima. This suggests that this definition includes not just the coldest and driest part of the last glacial cycle but also the peak in global ice volume. The later part of the LGM event is marked by Heinrich Event 2, which reflects the onset of the collapse of the Laurentide at c. 24 ka, together with other ice sheets in the North Atlantic region. A longer and later span for the LGM may be desirable, although defining this in chronostratigraphical terms is problematic. Whichever formal definition is chosen, this requires the contribution of the wider Quaternary community. [ABSTRACT FROM AUTHOR]

Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C (10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong) and a series of ESR (electron spin resonance) ages at Linzhi town and previous data by other experts, paleolakes persisted for 691∼505 kaBP middle Pleistocene ice age, 75-40 kaBP the early stage of last glacier, 27-8 kaBP Last Glacier Maximum (LGM), existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale: the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn't erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn't form stable lake. [ABSTRACT FROM AUTHOR]

Abstract: Large areas of Montenegro were glaciated during the Pleistocene. This paper presents evidence from the massifs of central Montenegro, including Durmitor and Sinjajevina, Moračke Planine, Maganik, Prekornica and Vojnik. Glacial deposits have been subdivided on the basis of morphostratigraphy and soil weathering and 31 U-series ages from cemented tills provided a geochronological framework. The largest glaciation occurred before 350 ka when a series of conjoined ice caps over the massifs of central Montenegro covered a total area of nearly 1500 km2. These formed during MIS 12 and correspond with the largest Skamnellian Stage glaciations in Greece to the south. Later Middle Pleistocene glaciations occurred during the penultimate glacial cycle correlating with the Vlasian Stage in Greece (MIS 6) when ice caps covered an area of 720 km2 over central Montenegro. There is also geochronological evidence of glacial deposits dating from the interval between MIS 12 and MIS 6, before the interglacial complex of MIS 7. This glaciation appears to have been very similar in extent to that which occurred during MIS 6. The last glacial cycle in central Montenegro was characterised by valley and cirque glaciers covering a total area of 49 km2. It is very likely that glaciers have been present in the mountains of central Montenegro during every glacial cycle since a small glacier still survives today. The smaller glaciers of the last glacial cycle are likely to have been associated with summer temperatures that were warmer than those of earlier cold stages. The striking contrast in the extent and thickness of ice cover during the cold stages of the Pleistocene has an important bearing on the geomorphological and biological evolution of the Balkans. [Copyright &y& Elsevier]

Abstract: Sand intraclasts are common within the Bacton Green Till Member, a glacitectonic mélange subjected to polyphase deformation during the Middle Pleistocene in North Norfolk, UK. The intraclasts range from a few tens of centimetres to >10 m in length and have sharp contacts with the surrounding till. Sand within the intraclasts is unconsolidated and contains well-preserved primary stratification. The wrapping of glacitectonic foliation around the intraclasts and the development of folds relating to mechanical instabilities indicate that the intraclasts acted as competent masses within a more easily deformable fine-grained till that accommodated the majority of the strain. Sharp contacts and distinctive heavy-mineral assemblages indicate little intermixing between the sand and till. Five hypotheses about the entrainment and evolution of the intraclasts are tested against sedimentological, structural and mineralogical observations. The most reasonable hypothesis attributes the intraclasts to glacitectonic deformation of “warm” permafrost. Initial ice advance caused large-scale thrusting of proglacial permafrost that led to the stacking of pre-glacial and ice-marginal sediments that were subsequently deformed sub-marginally to generate the intraclasts. Preservation of primary stratification within the intraclasts is attributed to deformation at temperatures slightly below the pressure-melting point, when pore ice cemented the intraclasts as rigid bodies. At the same time deformation was concentrated into the surrounding finer-grained till because of its significant liquid water content and ductile rheology. It is concluded that the intraclasts provide a criterion to identify past glacier–permafrost interactions and a potential means of differentiating between subglacial deformation under unfrozen and partially-frozen conditions. [Copyright &y& Elsevier]

Abstract: The reinvigoration of overturning in the Southern Ocean is hypothesized to have returned CO2 from the deep ocean to the atmosphere at the end of the last ice age. Large peaks in opal accumulation have been put forward as evidence for an increase in wind driven upwelling between 10 and 15ka. Here, we use coupled nitrogen and silicon isotope records alongside opal accumulation rates to provide quasi-quantitative estimates of Southern Ocean nutrient supply, by upwelling, and nutrient utilization across this interval. Significant changes in the consumption of N and Si across the two opal accumulation peaks indicate major changes in both upwelling and nutrient demand. We find N and Si consumption to be relatively incomplete during peak opal accumulation at the onset of the deglaciation. This indicates that nutrient supply was significantly enhanced. The second deglacial peak in opal accumulation is associated with more complete Si consumption and variable N consumption. We suggest that this peak represents strong upwelling and more complete utilization of the available silicic acid pool. Differences between the Si and N responses during opal peaks may stem from decreasing iron availability across the glacial termination. The nutrient isotope evidence for excess nutrients during the deglaciation indicates that the high export productivity was insufficient to overcome the evasion of CO2 to the atmosphere as a result of physical circulation changes. Previous work has demonstrated that the reinvigoration of overturning circulation during the deglaciation causes a transient peak in nutrient supply to the low latitudes. This is supported by our data, which indicate that relatively high macronutrient concentrations were maintained in the Southern Ocean surface waters that are incorporated into mode waters despite high demand. [Copyright &y& Elsevier]

Abstract: The type section silts of the late Pleistocene Wilson Creek Formation at Mono Lake contain outsized clasts, dominantly well-rounded pebbles and cobbles of Sierran lithologies. Lithic grains >425μm show a similar pattern of variability as the >10mm clasts visible in the type section, with decreasing absolute abundance in southern and eastern outcrops. The largest concentrations of ice-rafted debris (IRD) occur at 67–57ka and 46–32ka, with strong millennial-scale variability, while little IRD is found during the last glacial maximum and deglaciation. Stratigraphic evidence for high lake level during high IRD intervals, and a lack of geomorphic evidence for coincidence of lake and glaciers, strongly suggests that rafting was by shore ice rather than icebergs. Correspondence of carbonate flux and IRD implies that both were mainly controlled by freshwater input, rather than disparate non-climatic controls. Conversely, the lack of IRD during the last glacial maximum and deglacial highstands may relate to secondary controls such as perennial ice cover or sediment supply. High IRD at Mono Lake corresponds to low glacial flour flux in Owens Lake, both correlative to high warm-season insolation. High-resolution, extra-basinal correlation of the millennial peaks awaits greatly improved age models for both records. [Copyright &y& Elsevier]

Abstract: The Lavras do Sul Au–Cu mining district, southern Brazil, hosts an Ediacaran plutonic–volcanic association with hydrothermal alteration. This association is interpreted as a ca. 600–580Ma tilted porphyry–epithermal system, where the main ore occurs in phyllic and intermediate argillic halos around quartz veins. In this paper we used detailed field mapping, fluid inclusion microthermometry, oxygen and hydrogen isotope measurements of whole-rocks, feldspars, clay minerals and quartz from propylitic, phyllic and intermediate argillic alteration to reconstruct the hydrothermal fluid temperatures and compositions. The results showed that the deeper zones of the hydrothermal system were predominantly influenced by magmatic fluid and its shallower zones by meteoric water with very negative δ18O compositions. Our data support a model of mixing between magmatic-derived fluids with meteoric waters of glacial origin. Based on stable isotope data we propose indirect evidence of high latitude position for the study area during Brasiliano/Pan-African convergence of the Kalahari and Rio de La Plata cratons. [Copyright &y& Elsevier]

U-series age patterns obtained on reef framework-forming cold-water corals collected over a nearly 6000-km-long continental margin sector, extending from off Mauritania (17°N; northwest Africa) to the southwestern Barents Sea (70°N; northeastern Europe), reveal strong climate influences on the geographical distribution and sustained development of these ecosystems. Over the past three glacial-interglacial cycles, framework-forming cold-water corals (Lophelia pertusa and Madrepora oculata) seem to have predominantly populated reefs, canyons, and patches in the temperate East Atlantic and the Mediterranean Sea. Above 50°N corals colonize reefs in the northern East Atlantic primarily during warm climate periods with the biogeographic limit advancing from ~50°N to ~70°N. We propose that north-south oscillations of the biogeographic limit of reef developments are paced by ice ages and may occur synchronously with north-south displacement of cold nutrient-rich intermediate waters and surface productivity related to changes of the polar front. [ABSTRACT FROM AUTHOR]

Abstract: Late Glacial terrain in the Schwarzensteinkees, Hornkees and Waxeckkees forelands of the Zillertal Alps is dominated by sediments deposited by readvancing ice emplaced in the Little Ice Age, starting approximately 550±70cal 14C yr BP. Late Glacial ice scoured the massif with remnants of Late Glacial end moraines fronting LIA end moraines and buried paleosols underlying LIA end moraines providing scattered evidence of compositional change and weathering since the Later Dryas. The amount of recovered wood from LIA moraines indicates that the massif was forested for at least part of mid-Holocene times, most likely during the Atlantic Chronozone when, presumably, soil morphogenesis was accelerated. Details of till composition and weathering history provide a pedostratigraphic reconstruction which includes mid-LIA readvances between 400±70cal 14C yr BP and 350±70 cal14C yr BP. The heavily convoluted character of underlying early LIA or older tills suggests either pre-existing strongly active cryoturbation in a thin Entisol (Regosol) or active push moraine dynamics of advancing warm ice. SEM analysis documents differences in glacial dynamics that may be related to ice thickness, stick–slip motion or clastic load in the ice coupled with rate of movement. [Copyright &y& Elsevier]

Abstract: This study focuses on the exceptionally high occurrence of Orbulina suturalis and morphotypes very close to Praeorbulina in Late Glacial sediments from the Northern Arabian Sea. The genus Praeorbulina has been described by Blow (1956) as an ancestor of Orbulina universa. Our study is based on the analysis of three sediment cores retrieved in the Gulf of Oman (KS01, MD04-2849, and MD04-2861), covering the Late Pleistocene (last 30ka CAL-BP). Planktonic foraminiferal assemblages were investigated and revealed that this remarkable abundance of Orbulina suturalis, and numerous specimens morphologically close to Praeorbulina, occurs during a short time interval roughly representing the Last Glacial Maximum. One AMS 14C date was obtained on a monospecific sample of Praeorbulina-like specimens, giving an age of 19 CAL-ka BP, which confirms the Late Glacial age and unreworked character of this population. In this paper, we discuss the morphological similarities relating the observed Praeorbulina-like specimens to the genera Orbulina and Praeorbulina. We will also discuss the period of occurrence of these specimens and the potential environmental changes that may have caused their atypical morphology. [Copyright &y& Elsevier]

Abstract: Woolly mammoths were large, herbivorous, cold-adapted mammals of the Late Pleistocene. The diet and habitat requirements of the species set certain constraints on the palaeoenvironments it could occupy. The relationship between the mammoth’s shifting range and changing environments can be explored using independent data on ice sheet configuration, temperature, and vegetation, provided the locality and age of the fossil remains can be validated. Here we present a comprehensive record of occurrence of the woolly mammoth in the circum-Baltic region of northern Europe during the last glaciation, based on a compilation of radiocarbon-dated remains. The record shows that the mammoth was widespread in northern and north-eastern Europe during Marine Isotope Stage 3 (MIS 3), at 50,000–30,000 calibrated years ago (50–30ka). The presence of the species up to 65°N latitude supports the restriction of the Scandinavian Ice Sheet (SIS) during MIS 3. The widest distribution range round 30ka was followed by a decline that led to the disappearance of mammoths from the area during the maximum extent of the SIS, from 22 to 18ka. The woolly mammoth re-colonized the Baltic region and southern Scandinavia after the onset of the late-glacial deglaciation at 17ka. The late-glacial record suggests a markedly fluctuating population changing its range in tune with the rapid environmental changes. The last appearance of mammoth in our study region was in Estonia during the Younger Dryas (Greenland Stadial 1; GS1) at about 12ka. The two major periods of occurrence during MIS 3 and the late-glacial stadial suggest that mammoth had a wide tolerance of open to semi-open tundra and steppe-tundra habitats with intermediately cold climate, whereas the 22–18ka disappearance suggests a major southward and/or eastward retreat in response to extremely cold, glacial conditions near the SIS margin. The final regional extinction correlates with the re-forestation during the rapid warming at the Younger Dryas–Holocene boundary. [Copyright &y& Elsevier]

Abstract: Middle Pleistocene warm periods are particularly useful for comparison with our present warm period. One of them, Marine Isotope Stage (MIS) 11, has been considered a potential analogue for the Holocene, whereas older interglacials, e.g. MIS 13, are distinctly different. However, terrestrial Middle Pleistocene sites, other than the Holsteinian, and quantitative climate reconstructions for this period are very rare in Europe. A unique terrestrial site in North Central Europe is known from Bilshausen, Germany. The sediments are varved and indicate that this interglacial lasted ∼25,000 years, more than twice as long as the Holocene so far. The warm period probably correlates to MIS 11, or possibly to MIS 13. A new palynological investigation with large pollen counts is presented which forms the basis for quantitative temperature reconstructions based on the probabilistic indicator taxa approach (the so-called pdf-method). The range of tree species that formed the vegetation during the Bilshausen warm period is reminiscent of the Holocene, but the vegetational as well as the reconstructed climatic development shows distinct differences. No pronounced initial successional phase is recorded in the pollen stratigraphy from Bilshausen. In addition, a mesocratic or optimum phase of forest development as in the Holocene is unclear in the Bilshausen sequence. Reconstructed temperature values are several °C lower than Holocene temperatures for most of the Bilshausen interglacial. Only for several millennia in the late phase of the Bilshausen interglacial were July temperatures higher than the Holocene July temperatures. Seasonality was much stronger during the Bilshausen interglacial and the temperature trends differ between the two interglacials. Likely reasons for the pronounced differences are, on one hand, global temperature, insolation changes and atmospheric circulation. On the other hand, more regional factors such as the configuration of the North Sea basin may also be responsible for the colder winter temperatures and stronger seasonality during the Bilshausen interglacial compared to the Holocene. Reliable absolute dating of the Bilshausen interglacial is needed, which would allow a more detailed evaluation of the forcing factors that determined the climate during the Bilshausen interglacial. [Copyright &y& Elsevier]

More than a half of the northern Asian pool of human mitochondrial DNA (mtDNA) is fragmented into a number of subclades of haplogroups C and D, two of the most frequent haplogroups throughout northern, eastern, central Asia and America. While there has been considerable recent progress in studying mitochondrial variation in eastern Asia and America at the complete genome resolution, little comparable data is available for regions such as southern Siberia - the area where most of northern Asian haplogroups, including C and D, likely diversified. This gap in our knowledge causes a serious barrier for progress in understanding the demographic pre-history of northern Eurasia in general. Here we describe the phylogeography of haplogroups C and D in the populations of northern and eastern Asia. We have analyzed 770 samples from haplogroups C and D (174 and 596, respectively) at high resolution, including 182 novel complete mtDNA sequences representing haplogroups C and D (83 and 99, respectively). The present-day variation of haplogroups C and D suggests that these mtDNA clades expanded before the Last Glacial Maximum (LGM), with their oldest lineages being present in the eastern Asia. Unlike in eastern Asia, most of the northern Asian variants of haplogroups C and D began the expansion after the LGM, thus pointing to post-glacial re-colonization of northern Asia. Our results show that both haplogroups were involved in migrations, from eastern Asia and southern Siberia to eastern and northeastern Europe, likely during the middle Holocene. [ABSTRACT FROM AUTHOR]

Abstract: The Mid-Brunhes Event (MBE) is a climatic transition occurring between MIS 13 and 11 that separates two climatic modes: (1) early Middle Pleistocene interglacials (780–450ka) that are characterised by only moderate warmth and (2) Middle and Late Pleistocene interglacials (occurring after 450ka) that are characterised by greater warmth consistent with, or warmer than, the Holocene. This event is observable within a variety of long climate records, such as SPECMAP and EPICA, but its effect on terrestrial systems is poorly understood. The impact of this event is examined in the British terrestrial sequence by comparing the occurrence of a range of thermophilous plant and animal species, and climate reconstructions derived from assemblages containing them, from interglacials of the early Middle Pleistocene with those from the late Middle and Late Pleistocene. This comparison reveals that interglacial climates during the early Middle Pleistocene in Britain were as warm as, and in some cases warmer than, those that occurred during the late Middle and Late Pleistocene. This interpretation is supported by sea surface temperature records in the North Atlantic, which show that temperatures during early Middle Pleistocene interglacials were at least as warm as those experienced during the Holocene. There is, therefore, no evidence in climate records of Britain and the North Atlantic for a Mid-Brunhes Event. This suggests that the MBE is not a global climatic transition but is restricted to specific regions, in particular the higher latitudes of the southern Hemisphere. Further work is needed to understand the regional variability and cause of the MBE. [ABSTRACT FROM AUTHOR]

Abstract: The Antarctic Polar Front is an important biogeochemical divider in the Southern Ocean. Laminated diatom mat deposits record episodes of massive flux of the diatom Thalassiothrix antarctica beneath the Antarctic Polar Front and provide a marker for tracking the migration of the Front through time. Ocean Drilling Program Sites 1091, 1093 and 1094 are the only deep piston cored record hitherto sampled from the sediments of the circumpolar biogenic opal belt. Mapping of diatom mat deposits between these sites indicates a glacial-interglacial front migration of up to 6 degrees of latitude in the early/mid Pleistocene. The mid-Pleistocene transition marks a stepwise minimum 7° northward migration of the locus of the Polar Front sustained for about 450 kyr until an abrupt southward return to a locus similar to its modern position and further south than any mid-Pleistocene locus. This interval from a “900 ka event” that saw major cooling of the oceans and a δ13C minimum through to the 424 ka Mid-Brunhes Event at Termination V is also seemingly characterised by 1) sustained decreased carbonate in the sub-tropical south Atlantic, 2) reduced strength of Antarctic deep meridional circulation, 3) lower interglacial temperatures and lower interglacial atmospheric CO2 levels (by some 30 per mil) than those of the last 400 kyr, evidencing less complete deglaciation. This evidence is consistent with a prolonged period lasting 450 kyr of only partial ventilation of the deep ocean during interglacials and suggests that the mechanisms highlighted by recent hypotheses linking mid-latitude atmospheric conditions to the extent of deep ocean ventilation and carbon sequestration over glacial-interglacial cycles are likely in operation during the longer time scale characteristic of the mid–Pleistocene transition. The cooling that initiated the “900 ka event” may have been driven by minima in insolation amplitude related to eccentricity modulation of precession that also affected low latitude climates as marked by threshold changes in the African monsoon system. The major thresholds in earth system behaviour through the mid–Pleistocene transition were likely governed by an interplay of the 100 kyr and 400 kyr eccentricity modulation of precession. [Copyright &y& Elsevier]

Abstract: Osmium isotope composition (187Os/188Os) and concentrations of Os, Ir and Pt are reported for an early Pleistocene section from the ODP Site 849 in the eastern equatorial Pacific. Using the data obtained in this study, the contributions from detrital and extraterrestrial particulate matter to Os concentration and 187Os/188Os of sediment are estimated. Our calculations show that detrital contributions to sedimentary Os are too small (<2%) to significantly shift measured bulk sediment 187Os/188Os away from seawater values. A moderate but significant negative correlation between 187Os/188Os and 3He/188Os indicate that the average particulate extraterrestrial Os flux to this site is 1.21±0.47pgcm−2 kyr−1, which constitutes ⩽3% of total Os burial flux. The estimates of detrital and extraterrestrial Os are used to calculate the seawater 187Os/188Os in the early Pleistocene. The most notable features of this early Pleistocene 187Os/188Os record are: (1) glacial–interglacial 187Os/188Os differences are insignificant within errors of estimates, (2) glacial 187Os/188Os values are higher compared to those reported for the late Pleistocene glacials. Comparison of 187Os/188Os values at Site 849 to the late Pleistocene records suggests that average seawater 187Os/188Os change has been modest (∼5%) since the early Pleistocene. Assuming that 187Os/188Os difference between the glacial periods of the late and the early Pleistocene results solely from temperature dependence of weathering rates, it has been calculated that average surface temperature during the late Pleistocene glacials was 0.8±0.2°C lower than glacials in the early Pleistocene. This inference is consistent with temperature estimates based on a recent study of pCO2 reconstruction in the Pleistocene. This observation based on limited studies of marine 187Os/188Os records seems to suggest that temperature played an important role in influencing chemical weathering during the Pleistocene glacials. However, more studies are needed to confirm if this temperature-weathering feedback was operational throughout the Pleistocene. A significant down core Ir–3He co-variation coupled with similar burial fluxes of Ir at Site 849 and at LL44 GPC-3 in the north Pacific point to the utility of Ir concentration as a point paleoflux tracer. However, a twofold difference in Ir burial fluxes between the eastern and the western equatorial Pacific suggests that calibration in space and time is required to use Ir concentration as a robust indicator of paleoflux through time. Significant co-variation of concentrations of Os and total alkenone during the glacials coupled with lighter δ13C of benthic foraminifera indicates that productivity and carbon burial played a dominant control on scavenging of Os at Site 849. In a broader context, this data set encourages future investigation of response of PGE behavior to paleoceanographic processes. [Copyright &y& Elsevier]

Abstract: The shallow-marine to coastal deposits of Alghero have been dated using the Optically Stimulated Luminescence (OSL) method, and studied to define the palaeoenvironmental evolution of coastal areas in northwest Sardinia. Dating, coupled with sedimentological and stratigraphical analyses, allowed the subdivision of the succession in four unconformity-bounded units (U2, U3a, U3b, U4). Unit U2 of penultimate glacial stage (MIS 6; ca. 150ka) is composed of dune deposits formed intermittently along rocky coastal areas under strong wind conditions. Subunit U3a is composed of cliff-bounded gravelly dominated pocket beach deposits, commonly highly fossiliferous, and is assigned to the interglacial MIS 5e (ca. 125ka). Subunit U3b is characterized by sandy beach to coastal systems of the isotopic sub-stage MIS 5c (ca. 100ka). The unconformity between U3b and U4 marks the initiation of last glacial regression (MIS 5a/4; ca. 77ka) during which shelf areas were exposed and small incised valleys developed. Along the valley flanks, colluvial or sheetflood sediments were deposited and, in the central part thick reddish paleosols formed. Valleys were eventually filled by thick aeolian dune deposits (MIS 4–3) indicating persistent inland sand transport. Around Alghero, coastal carbonate-rich dunes preferentially formed and migrated inland during lowstand and falling stages when the climate is relatively cold, vegetation is quite open, winds are fairly strong and sediment supply from exposed shelf areas is high. [Copyright &y& Elsevier]

Abstract: Chloride and δ 18O compositions of interstitial water extracted from a long sediment core retrieved from the NW coast of the Black Sea allowed us to constrain the main hydrologic changes of the Back Sea during the Late Pleistocene and Holocene. Prior to its reconnection with the Mediterranean Sea (through the Marmara Sea) at approximately 9000 calendar yr before present (9kacalBP), the Black Sea has evolved as a fresh to brackish water lake. At the time of reconnection, hydrologic changes were drastic. Bottom water salinities changed from a few psu (practical salinity unit) to ∼22psu. Since solutes in the interstitial water column within sediments are advected and diffused the measured concentrations do not reflect those of past bottom waters. In order to reconstruct these former concentrations, we used an advection/diffusion model. Different scenarios of bottom water chloride and δ 18O variations were accounted for in this model in order to simulate “present day” vertical profiles for concentrations of interstitial water in order to compare them to measured ones. The comparison suggests that the glacial Black Sea was a homogeneous freshwater lake (with a δ 18O of ∼−10‰ and a salinity of ∼1psu). Modern hydrologic conditions would only have been reached at ∼2kacalBP, concomitant with the onset of coccolith-rich thin layers that characterize modern basin sediments. Such delayed salinization (over ∼7000yr) in the basin may have been due to higher precipitation during the early Holocene. We also simulated the impact of a catastrophic reconnection and a smoother reconnection. Both salinity scenarios lead to undistinguishable modelled “present day” profiles, indicating that the precise impact of the last reconnection was lost due to the advection/diffusion processes. [Copyright &y& Elsevier]

Communities have been shaped in numerous ways by past climatic change; this process continues today. At the end of the Pleistocene epoch about 11,700 years ago, North American communities were substantially altered by the interplay of two events. The climate shifted from the cold, arid Last Glacial Maximum to the warm, mesic Holocene interglacial, causing many mammal species to shift their geographic distributions substantially. Populations were further stressed as humans arrived on the continent. The resulting megafaunal extinction event, in which 70 of the roughly 220 largest mammals in North America (32%) became extinct, has received much attention. However, responses of small mammals to events at the end of the Pleistocene have been much less studied, despite the sensitivity of these animals to current and future environmental change. Here we examine community changes in small mammals in northern California during the last ‘natural’ global warming event at the Pleistocene–Holocene transition and show that even though no small mammals in the local community became extinct, species losses and gains, combined with changes in abundance, caused declines in both the evenness and richness of communities. Modern mammalian communities are thus depauperate not only as a result of megafaunal extinctions at the end of the Pleistocene but also because of diversity loss among small mammals. Our results suggest that across future landscapes there will be some unanticipated effects of global change on diversity: restructuring of small mammal communities, significant loss of richness, and perhaps the rising dominance of native ‘weedy’ species. [ABSTRACT FROM AUTHOR]

The first comparative and systematic climate model study of the sensitivity of the climate response under Last Glacial Maximum (LGM) conditions to freshwater perturbations at various locations that are known to have received significant amounts of freshwater during the LGM (21 kyr BP) climate conditions is presented. A series of ten regions representative of those receiving most of the meltwater from decaying ice-sheets during the deglaciation is defined, comprising the border of LGM ice-sheets, outlets of rivers draining part of the melting ice-sheets and iceberg melt zones. The effect of several given freshwater fluxes applied separately in each of these regions on regional and global climate is subsequently tested. The climate response is then analysed both for the atmosphere and oceans. Amongst the regions defined, it is found that the area close by and dynamically upstream to the main deep water formation zone in the North Atlantic are most sensitive to freshwater pulses, as is expected. However, some important differences between Arctic freshwater forcing and Nordic Seas forcing are found, the former having a longer term response linked to sea-ice formation and advection whereas the latter exhibits more direct influence of direct freshening of the deep water formation sites. Combining the common surface temperature response for each respective zone, we fingerprint the particular surface temperature response obtained by adding freshwater in a particular location. This is done to examine if a surface climate response can be used to determine the origin of a meltwater flux, which is relevant for the interpretation of proxy data. We show that it is indeed possible to generally classify the fingerprints by their origin in terms of sea-ice modification and modification of deep-water formation. Whilst the latter is not an unambiguous characterization of each zone, it nonetheless provides important clues on the physical mechanisms at work. In particular, it is shown that in order to obtain a consistent see-saw temperature pattern, addition of freshwater in the Northern Hemisphere at sites dynamically close to the deep water formation zones is needed. Finally a preliminary data—model comparison for the time of the Heinrich event 1 suggests that those sites are indeed the most favourable to explain the pattern of climate variability recorded in proxy data for this period. More importantly, this model—data comparison enables us to clearly reject a substantial fraction of the zones tested as potential source for large freshwater entering the ocean at that time. [ABSTRACT FROM AUTHOR]

Stanford, S. D. 2009: Onshore record of Hudson River drainage to the continental shelf from the late Miocene through the late Wisconsinan deglaciation, USA: synthesis and revision. Boreas, 10.1111/j.1502-3885.2009.00106.x. ISSN 0300-9483. Fluvial and glacial deposits in New Jersey, Long Island, and the Hudson valley provide a record of Hudson River drainage since the late Miocene. Late Miocene fluvial deposits record southerly flow across the emerged inner New Jersey shelf. In the late Miocene–early Pliocene this drainage incised, shifted southwesterly, and discharged to the shelf south of New Jersey. During late Pliocene or Early Pleistocene glaciation, discharge to the shelf in the New York City area was established. This drainage incised and stabilized in the Early and Middle Pleistocene and remained open during pre-Wisconsinan (Oxygen Isotope Stage 6? (OIS-6?)) and late Wisconsinan (OIS-2) glacial advances. During late Wisconsinan retreat, moraine deposits dammed the valley at the Narrows to form Lake Albany. From 19 to 15.5 kyr BP (all dates in 14C yr), Hudson drainage was directed eastward into the Long Island Sound lowland. Drainage of Lake Wallkill into Lake Albany at 15.5 kyr BP breached the Narrows dam and initiated the unstable phase of Lake Albany, which was controlled by eroding spillways, first on the moraine dam, then on emerged lake-bottom in the mid-Hudson valley. Marine incursion between 12 and 11 kyr BP limited fluvial incision of the lake bottom, stabilizing the Quaker Springs, Coveville, and upper Fort Ann spillways. Lowering sea level between 11 and 10 kyr BP allowed incision from the upper to lower Fort Ann threshold. Sediment eroded by lake outflows between 15 and 10.5 kyr BP was trapped in the glacially deepened lower valley. Little inland sediment reached the shelf after 20 kyr BP. [ABSTRACT FROM AUTHOR]

The article offers information on the landscape evolution in the Southern Kurile Islands, Russia during the transition from Pleistocene Epoch to Holocene period. According to the authors, the southern Kurile Islands is a portion of the former land bridge that connected the Lesser Kurile, Kunashir Island and Hokkaido islands in Japan. The later part of Pleistocene was characterized by short periods of climate fluctuations such as warming and cooling episodes that resulted to transformation of landscapes. The authors noted that the early middle Holocene's warm climate conditions have yielded dark coniferous forests up to the late Middle Holocene. However, in the late Holocene, there was a rapid landscape reorganization.

Abstract: The Ecemiş River developed during the Pleistocene and Holocene in the Ecemiş basin. The basin developed because of tectonic movement on the Ecemiş Fault, which is west of the Aladağ Mountains. In the Pleistocene, glacial–interglacial climate changes directly affected the regimes and discharges of rivers, causing changes in river levels along the Ecemiş channel. Fluvial formations became extremely complicated when active tectonic movements accompanied the changes resulting from the climatic conditions. The rivers embedded in their beds according to new local base levels in interglacials. Terraces formed due to interruptions in the cycle of morphological development along the Ecemiş River. From the morphologic structure of these terraces and their positions in the Ecemiş Valley two groups and five levels of terraces were defined. In the Ecemiş Valley, modern terraces (1–5m) formed in the Holocene, while low terrace systems (5–10m and 15–20m) and high terrace systems (30–40 and 70–80m) formed in the Pleistocene. [Copyright &y& Elsevier]

Abstract: The Piànico-Sèllere is a lacustrine succession from northern Italy that records a sequence of climatic transitions across two Pleistocene glacial stages. The intervening interglacial stage is represented by well-preserved varves with calcitic (summer) and clastic (winter) laminae. There is a tight coupling between climate-driven lithologic changes and magnetic susceptibility variations, and stable paleomagnetic components were retrieved from all investigated lithologies including the largely diamagnetic calcite varves. These components were used to delineate a sequence of magnetic polarity reversals that was interpreted as a record of excursions of the Earth''s magnetic field. Comparison of the magnetostratigraphic results with previously published data allows discussion of two possible models which have generated controversy regarding the age of the Piànico Formation. The data indicates that the Piànico Formation magnetostratigraphy correlates to geomagnetic field excursions across the Brunhes/Matuyama transition, and consequently the Piànico interglacial correlates to marine isotope stage 19. This correlation option is substantially consistent with K–Ar radiometric age estimates recently obtained from a tephra layer interbedded in the Piànico Formation. The alternative option, considering the Piànico interglacial correlative to marine isotope stage 11 within the Brunhes Chron as supported by tephrochronological dating reported in the literature, is not supported by the magnetostratigraphic results. [Copyright &y& Elsevier]

Abstract: The chronostratigraphic position of the Piànico carbonate sequence, Oroebic Alps, Italy remains controversial, notwithstanding that it is one of the best-preserved records of an alpine interglacial. Two distal tephra were discovered in the sequence. The lowermost (t21d) is a rhyolitic tephra dated by K–Ar at 779±13ka, different from the uppermost phonolitic tephra (t32) with an assigned age of 393±12ka. The volcanic source of t32 was recently interpreted as being the Brown Leucitic Tuff of the Roccamonfina volcano, southern Italy. New trace element and Nd and Sr isotopic composition of t32 and of 420–200ka volcanic products of the Roccamonfina clearly indicate that this volcano is not the source of t32, but that it likely originated from the northern Roman Magmatic Province. The products of the initial explosive activity of Sabatini Mts., dated ca. 780–800ka, isotopically match t32 and are proposed as its source. This indicates that the previously inferred age of ∼400ka for t32 is erroneous. New isotopic and geochemical data of t21d confirm it as being associated with the first pyroclastic eruptions (790–710ka) of the Puy de Sancy volcano, French Massif Central. The Early-Middle Pleistocene K–Ar ages obtained previously for t21d, together with the isotopic attribution of volcanic sources to both tephra layers presented here, confirm Piànico as one of the best interglacial sequences of Cromerian age in the Western Alps. [Copyright &y& Elsevier]

During the Pleistocene, climatic fluctuations due to glacial and interglacial periods greatly modified the distribution of boreal organisms. One direct effect of these distribution shifts is that, along the southern edge of the range of some boreal species, populations persist only in isolated patches of suitable habitats, surrounded by less suitable areas. Isolated populations in marginal habitat are vulnerable to several threats, including climate change, anthropogenic threats, and stochastic events. We developed habitat-suitability models using Ecological Niche Factor Analysis for populations of the smooth snake, Coronella austriaca, at the southernmost limit of the species range. These models were based on historical and current records of occurrence, coupled with remote sensing data including elevation, slope, and climatic variables. Our results indicated that C. austriaca in the Iberian Peninsula occurred in areas associated with high slope and precipitation, low temperatures, and low variation in seasonal temperature and precipitation compared to areas of non-occurrence. At a broad scale, the areas classified as highly suitable for the species in the southern Iberian Peninsula were small and fragmented. At a local scale, extensive field work demonstrated that C. austriaca occurs in low densities in these areas. In addition, we detected several human-induced threats like habitat loss, favoured by temperature increase and rainfall reduction. Several life-history traits, such as dietary specialization and low frequency reproduction, also may contribute to the vulnerability of these populations to local extinctions. Although the most suitable southernmost areas are included in protected reserves, specific guidelines for management are needed to assess conservation needs. [Copyright &y& Elsevier]

Abstract: In the Alps, interglacial and interstadial deposits are rarely preserved due to the intense erosive effect of glaciers in the valleys. Fortunately, some outcrops and cored sequences located in the field area ranging from Lyon to Evian provided sedimentary profiles datable by palynostratigraphy in a highly documented geomorphological context. An overview of several palynological sequences studied in this large area is proposed, and their position in a general chronostratigraphical pattern is discussed. Particular attention is paid to palynostratigraphical evidence whose relevance is tested with systematic comparisons with long reference European pollen sequences spanning several glacial cycles. Minimum ages are suggested for non-glacial episodes corresponding to the deposits studied. [Copyright &y& Elsevier]

Abstract: Vegetation feedback at the Last Glacial Maximum (LGM, about 21,000 calendar years ago) remains an unresolved question. A global atmospheric general circulation model (AGCM) is asynchronously coupled with an equilibrium terrestrial biosphere model in the present study. The coupled model is then used to investigate the influences of vegetation and soil feedbacks on the LGM climate. It is found that the simulated geographical distribution of vegetation at the LGM differs from the present pattern dramatically, and glacial vegetation cover tends to be reduced on average. Vegetation feedback alone leads to an annual surface temperature decrease of 0.31 °C over the LGM ice-free continental areas. Additional soil feedback reinforced vegetation-induced cooling over high latitude Eurasia and from the eastern Middle East eastward to the Indian Peninsula significantly. In the tropics, a terrestrial annual surface cooling of 0.45 °C is produced by vegetation and soil feedbacks. It is shown that vegetation and soil feedbacks partly reduce data-model discrepancy as produced by the AGCM alone in some regions such as Central Africa, the Indian Peninsula, South China, and North Australia. [Copyright &y& Elsevier]

Abstract: The southeast sector of the Greenland Ice Sheet is currently experiencing rapid changes in mass balance and ice sheet dynamics at low elevations. However, to what extent these changes are typical of the behaviour of this sector of the ice sheet is uncertain, as our understanding of the longer-term controls on ice sheet dynamics in this region is limited. Two models exist for Last Glacial Maximum (LGM) ice sheet configuration in east Greenland. The first “minimum” model envisages a restricted ice sheet, with exposed nunataks in coastal areas and limited ice extent onto the continental shelf fed by ice flowing through bedrock troughs. A second, “maximum” model entails a thicker ice sheet with limited coastal nunataks, and ice filling the coastal valleys and extending across the entire continental shelf. Radiocarbon dates on foraminifera collected from seabed cores on the southeast Greenland continental shelf suggest that the ice sheet reached a maximum extent at ca 22kcal.yr, before retreating, perhaps as early as ca 17kcal.yrBP, and reaching the present coast at ca 10kcal.yrBP. This paper presents the results of a study designed to test these different ice sheet models based on geomorphological mapping and cosmogenic isotope analyses in the Torqulertivit Imiat valley, an area to the east of the coastal town of Ammassalik. 26Al and 10Be measurements on abraded bedrock surfaces in terrain above local trimlines yield surface exposure ages of ca 11.8–9.9ka. This demonstrates warm-based glacial erosion of high level surfaces (ca 740m asl), followed by trimline formation during deglaciation and intense postglacial weathering. Our work constrains minimum ice thickness during the LGM to at least 740m and supports a “maximum” ice sheet model in this sector of the GIS. Ice sheet retreat from the continental shelf to the southern edge of Sermilik Fjord is dated to ca 11.1–9.7ka and helps to constrain the timing of the early Holocene retreat of the Helheim Glacier ice stream. Within the Torqulertivit Imiat valley, age determinations from glacially abraded terrain above the local marine limit on the coast (11.1–9.7ka) and those from 10km up-valley (12.8–9.9ka), suggest rapid surface ablation during these intervals, coincident with rapid atmospheric warming observed in the Greenland ice core records. [Copyright &y& Elsevier]

Contemporary evolution of Pacific salmon ( Oncorhynchus spp.) is best viewed in the context of the evolutionary history of the species and the dynamic ecosystems they inhabit. Speciation was complete by the late Miocene, leaving c. six million years for intraspecific diversification. Following the most recent glacial maximum, large areas became available for recolonization. Current intraspecific diversity is thus the product of recent evolution overlaid onto divergent historical lineages forged during recurrent episodes of Pleistocene glaciation. In northwestern North America, dominant habitat features have been relatively stable for the past 5000 years, but salmon ecosystems remain dynamic because of disturbance regimes (volcanic eruptions, landslides, wildfires, floods, variations in marine and freshwater productivity) that occur on a variety of temporal and spatial scales. These disturbances both create selective pressures for adaptive responses by salmon and inhibit long-term divergence by periodically extirpating local populations and creating episodic dispersal events that erode emerging differences. Recent anthropogenic changes are replicated pervasively across the landscape and interrupt processes that allow natural habitat recovery. If anthropogenic changes can be shaped to produce disturbance regimes that more closely mimic (in both space and time) those under which the species evolved, Pacific salmon should be well-equipped to deal with future challenges, just as they have throughout their evolutionary history. [ABSTRACT FROM AUTHOR]

We examine the evolutionary history and speculate about the evolutionary future of three basic life history ecotypes that contribute to the biocomplexity of sockeye salmon ( Oncorhynchus nerka). The ‘recurrent evolution’ (RE) hypothesis claims that the sea/river ecotype is ancestral, a ‘straying’ form with poorly differentiated (meta)population structure, and that highly structured populations of lake-type sockeye and kokanee have evolved repeatedly in parallel adaptive radiations between recurrent glaciations of the Pleistocene Epoch. Basic premises of this hypothesis are consistent with new, independent evidence from recent surveys of genetic variation in mitochondrial and microsatellite DNA: (1) sockeye salmon are most closely related to pink ( O. gorbuscha) and chum ( O. keta) salmon with sea-type life histories; (2) the sockeye life history ecotypes exist as polyphyletic lineages within large drainages and geographic regions; (3) the sea/river ecotype exhibits less genetic differentiation among populations than the lake or kokanee ecotypes both within and among drainages; and (4) genetic diversity is typically higher in the sea/river ecotype than in the lake and kokanee ecotypes. Anthropogenic modification of estuarine habitat and intensive coastal fisheries have likely reduced and fragmented historic metapopulations of the sea/river ecotype, particularly in southern areas. In contrast, the kokanee ecotype appears to be favoured by marine fisheries and predicted changes in climate. [ABSTRACT FROM AUTHOR]

Ice scouring of lake and sea-floor substrates by the keels of drifting ice masses is a common geological process in modern northern lakes and continental shelves, and was widespread during the Pleistocene. Nonetheless, the importance of scouring as a geological process is not yet matched by many sedimentological studies of scour structures exposed in outcrop. This article presents an integrated study combining outcrop sedimentology and subsurface ground-penetrating radar (GPR) data from a relict late Pleistocene ice-scoured glacial lake floor now preserved below beach sediments in Ontario, Canada. Scours occur along a regressive sequence boundary where deep-water muddy facies are abruptly overlain by shallow-water sands resulting from an abrupt drop in water levels. This has allowed the keels of drifting ice masses to scour into muds. Three-dimensional data gained from the GPR survey show that scours are as much as 2.5 m deep and 7 m wide; they have berms of displaced sediment and are oriented parallel to the former shoreline. Scoured shoreface sediments that fill scours show abundant liquefaction structures, indicating substrate dewatering during repeated scouring events similar to that recently reported in the modern Beaufort Sea in Canada's far north. Marked changes in water depths are typical of glacially influenced lakes and seas, creating opportunities for drifting ice to scour into offshore muddy cohesive facies and be preserved. The data presented here may aid identification in ancient successions elsewhere. [ABSTRACT FROM AUTHOR]

Abstract: Ocean variability at decadal time-scales remains poorly described partly because of the scarcity of high temporal resolution marine records. Here, we present a reconstruction of Sea Surface Temperatures (SSTs) over the past two millennia at unprecedented temporal resolution (2 to 5 years), from a marine core located off North Iceland. Alkenone paleothermometry was used to infer SST variability, and tephrochronology to build the age model. Spectral analyses of the SST signal indicate intermittent 20–25 year oscillations, with periods of strong and weak power, that are likely reflecting the ocean response to wind forcing, presumably the North Atlantic Oscillation (NAO). Warmer SSTs and paleo-magnetic proxy data, between 1000 and 1350 year A.D., overlapping the Medieval Warm Period (MWP), suggest enhanced heat transport across the Denmark Strait by the North Icelandic Irminger Current (NIIC). This is in contrast with the subsequent period, which includes the Little Ice Age (LIA), showing continuous cooling towards the 20th century. Reduced NIIC flow through the Denmark Strait likely resulting from higher freshwater and sea ice export from the Arctic would account for the observed colder conditions. [Copyright &y& Elsevier]

The present distribution of freshwater fish in the Alpine region has been strongly affected by colonization events occurring after the last glacial maximum (LGM), some 20 000 years ago. We use here a spatially explicit simulation framework to model and better understand their colonization dynamics in the Swiss Rhine basin. This approach is applied to the European bullhead ( Cottus gobio), which is an ideal model organism to study fish past demographic processes since it has not been managed by humans. The molecular diversity of eight sampled populations is simulated and compared to observed data at six microsatellite loci under an approximate Bayesian computation framework to estimate the parameters of the colonization process. Our demographic estimates fit well with current knowledge about the biology of this species, but they suggest that the Swiss Rhine basin was colonized very recently, after the Younger Dryas some 6600 years ago. We discuss the implication of this result, as well as the strengths and limits of the spatially explicit approach coupled to the approximate Bayesian computation framework. [ABSTRACT FROM AUTHOR]

The article discusses the deep-water corals of the Red Sea. The Red Sea is capable of accommodating benthic ecosystem with its 2000 kilometers marginal basin that is elongated and semi-enclosed. However, the author mentions that the Red Sea has a poor known deep-water coral fauna from the Indian Ocean. It offers a background history of the deep-water corals in the Red Sea, and is accompanied with a chart that suggests the locations and depths of stations of the coral fauna. The author states that the high-salinity phase brought by the Last Glacial epoch was lethal to the stenoecious ecosystem in the Red Sea.

In conjunction with detailed geological mapping around the Aim and Straneggtal, in Upper Austria, the landslide deposits have been restudied. Along the southern flank of Meisenberg, coarse angular debris with boulders up to ca. 5m3 size occur. These are composed only of bright Dachsteinkalk sitting as erratic material on the dark-grey limestone of the Gutenstein Formation. The coarse grain size and its distribution only above the trim line of the Last Glacial Maximum (LGM) indicates that this material was deposited in a large-scale rock avalanche. This was derived from the northern rim of the Totes Gebirge and travelled north, spreading out over the glacier and finally reaching the flank of the Meisenberg, some 6km away. Similar deposits at Jh. Miraberg are also remnants of this debris blanket, deposited when the glacier finally malted away. The Hintere Hetzau cirque and the Staneggtal show a conspicuously hummocky topography, covered with huge blocks of Dachsteinkalk. The hummocks consist of densely packed matrix-supported angular debris of Dachsteinkalk and Hauptdolomit, deposited by a huge landslide (ca. 450 million ms. This was derived from the Büchsenkar and formed a sturzstrom filling the whole Straneggtal. The conspicuous ridges north and south of Drackhütte are surge ridges (Fleckberg) and wave-like ridges created by the dynamics of the sturzstrom. On reaching the Almtal, the sturtzstrom probably entered a shallow lake and was transformed into a suspension that was pushed forward by subsequent incoming material. This suspension flow created a terrace body as far north as the Grünau basin. Sedimentary structures indicate that this occurred in a single short event. Lumps of still dry and densely packed landslide material floated in and above the suspension, forming small hills on the surface of the terrace. Larger lumps of still stratified sandy-gravelly river sediments indicate transport in a frozen state indicating wintertime or early spring conditions. 36Cl surface exposure dating indicates that the avalanches occurred at the end of the LGM, probably shortly before the glaciers started their final melting. The boulders at Meisenberg were deposited around 19,000 years ago. The younger main event, at Straneggtal, took place at the end of the Oldest Dryas, after melting of the Gschnitz stadial glaciers; the most representative age of boulder deposition is 15,600 ± 1100 years. [ABSTRACT FROM AUTHOR]

In Taiwan, efficient climate-driven strong erosion processes are the leading cause for low preservation of geomorphic landforms. Despite the absence of present-day glaciers, glacial relicts have been reported in high altitude areas. These scarce landforms provide opportunities for reconstructing the timing of the last deglaciation in a region where glacial history is poorly documented. We have collected boulders and striated bedrocks in the Nanhutashan area and calculated surface exposure ages based on in-situ produced 10Be concentrations. The oldest glacial remains, dated at 11.1 ± 3.3 ka, correspond to the last glacial advance. The Holocene is characterized by a continuous retreat of the ice-cap until at least 7.2 ± 1.0 ka. Our results are in agreement with a scenario where changes of monsoon regimes lead to a strong reduction of the winter monsoon during the early Holocene, causing a decrease of snow supply and disequilibrium of the hydrological budget. [ABSTRACT FROM AUTHOR]

During the Last Glacial Maximum (LGM), a 5000 km2 ice cap covered the San Juan Mountains of southwest Colorado. The largest valley glacier draining this ice cap occupied the Animas Valley and fl owed 91 km to the south. To characterize the post-LGM demise of the Animas Valley glacier, we employ cosmogenic 10Be to date the LGM terrace outside the terminal moraines and a suite of seven glacially polished bedrock samples. The 10Be depth profile within the terrace sediments suggests abandonment at 19.4 ± 1.5 ka. As deglaciation began, the ponding of Glacial Lake Durango behind the terminal moraines shut off fluvial sediment supply and caused terrace abandonment. The age of the terrace therefore records the initiation of LGM retreat. Negligible 10Be inheritance in the terrace profile suggests that glacial erosion of the bedrock valley floor from which sediments were derived erased all cosmogenic inventory. Glacial polish exposure ages monotonically decrease up-valley from 17.1 to 12.3 ka, with the single exception of a sample collected from a quartzite rib, yielding an average retreat rate of 15.4 m/yr. This trend and the lack of inherited cosmogenic nuclides in the terrace sediments imply that polish ages accurately record the glacial retreat history. Retreat of the Animas lobe began at a time of regional drying recorded in sediments and shoreline elevations of large lakes. Deglaciation lasted for ∼7.2 k.y., and was complete by 12.3 ± 1.0 ka. The retreat history followed the pattern of increasing insolation and was perhaps fastest during a time of regional drying. [ABSTRACT FROM AUTHOR]

Theories that propose feedbacks among climate, tectonics, and surface processes commonly assume that erosion is enhanced by glacial activity. Indeed, studies have shown that glaciers appear to limit the elevation of mountain ranges; however, comparisons between rates of glacial and nonglacial erosion are difficult to make. Ideally, such comparisons must hold precipitation and lithology constant, while only varying the erosional regime. Located in a climatic transition zone during the Pleistocene, the east-west-trending valleys of the Bitterroot Range present an opportunity for a quantitative analysis of glacial and nonglacial erosion because the north-facing sides of the valleys were glaciated, whereas the south-facing slopes were not. The different erosional regimes operating on either side of the valleys created strongly asymmetric ridges. Ridgelines separating the east-west-trending valleys have been pushed southward by glacial headwall retreat such that ridge-to-valley distances are ∼50% greater on the north-facing slopes than on the south-facing slopes. In addition, mean hillslope angles are 6° lower on the glaciated slopes than on the unglaciated slopes, and calculations of geophysical relief suggest that, on average, glaciers have removed nearly twice as much rock as nonglacial processes. Finally, we conclude that, although rates of vertical incision by glacial processes in the Bitterroot Range were more rapid than nonglacial processes, the dominant geomorphological impact of glaciers was lateral erosion by headwall retreat. [ABSTRACT FROM AUTHOR]

Accelerator mass spectrometer 14C dating of in situ monospecific marine microfaunas and reworked shells records high relative sea level on the western coast of Ireland between ca. 40 and 19 cal (calibrated) ka, requiring substantial isostatic loading by the Irish ice sheet (IIS) during that interval. Glacial and marine deposits also record a rapid fluctuation of the HS margin onto the continental shelf ca. 28 cal ka. Evidence that the coast was not subsequently overridden by the IIS indicates that, at least for this sector of the ice sheet, the ice margin during the Last Glacial Maximum (LGM) was less extensive than the 28 cal ka event. Our data from western Ireland support 14C and 36Cl chronologies from the Irish Sea Basin in identifying an US that was as extensive and thick as the LGM IIS for much of the 20 k.y. interval prior to the LGM. [ABSTRACT FROM AUTHOR]

Subaerial exposure beside the Wandandian Creek channel during the last glacial maximum led to the development of red and orange mottling and, in some areas, produced a palaeosol over the Pleistocene land surface. Incision of the palaeo-Wandandian Creek, during the Late Pleistocene, formed a relatively deep steep-sided channel partially infilled with medium-grained fluvial sand. This palaeovalley became drowned as the post-glacial marine transgression impounded the western portion of St Georges Basin and the basal prodelta/lagoonal mud facies was deposited from ca 7 ka. The Wandandian Creek delta prograded down the palaeovalley and reached the study area &nvsim;3500 – 4000 years ago with the deposition of delta-front sandy silt and the overlying prograded sand facies. The subaerial portion of the delta is characterised by well-developed floodplains, levees, mouth bars and backswamps. Dredging in Wandandian Creek and land clearing for rural and urban development have had little long-term effect on the growth and morphology of Wandandian Creek delta. [ABSTRACT FROM AUTHOR]

This paper presents the first detailed study of a large assemblage of late Pleistocene artefacts from the central desert. Analysis of the lithics shows show that Puritjarra rock shelter was used more intensively over time, with significant shifts in the character of occupation at 18,000, 7,500 and 800 B.P., reflecting significant re-organization of activities across the landscape. The same generalized flake and core technology appears to have been used for over 30 millennia with only limited change in artefact typology over this period. [ABSTRACT FROM AUTHOR]

New Re-Os dates obtained from black shales overlying the Sturtian and Areyonga glacial deposits in southern and central Australia, respectively, challenge the prevailing consensus of three Neoproterozoic glaciations. The end of Sturtian glaciation in the Adelaide Rift Complex is constrained by a Re-Os date of 643.0 ± 2.4 Ma from the overlying Tindelpina Shale Member (basal Tapley Hill Formation). A Re-Os date of 657.2 ± 5.4 Ma for the basal Aralka Formation constrains the age of the underlying Areyonga glacial deposits in the Amadeus Basin. The Re-Os ages show that the Sturtian and Areyonga glacial deposits are younger than other radiometrically dated (ca. 685-750 Ma) Neoproterozoic glacial intervals previously regarded as possible correlatives. Thus, the "Sturtian" ice age was markedly diachronous, and/or there was more than one "Sturtian"-type glaciation. Some Neoproterozoic glacial deposits may represent the products of regional and diachronous glaciation associated with protracted breakup of the supercontinent Rodinia rather than "snowball" or "slushball" Earth ice ages. [ABSTRACT FROM AUTHOR]

Abstract: Exposures of Pliocene and Pleistocene deposits in the Ileret region include all eight members of the Koobi Fora Formation and represent at least 533m of section from the base of the Lonyumun Member to the top of the Chari Mb. This thickness is more than twice that reported by earlier workers (∼260m) and compares well with the composite section of the Koobi Fora Formation (525m). Thus the Ileret region provides a very complete and representative outcrop of the Koobi Fora Formation. As Koobi Fora Formation member boundaries are placed at the base of specified tuffs, not all member boundaries can be recognized in the Ileret region. For this reason, the stratigraphy is described in terms of the following members (thicknesses in parentheses): Lonyumun (110m), undifferentiated Moiti and Lokochot (104m), Tulu Bor (54m), Burgi (55m), KBS (74m), Okote (45m), and Chari (93m). Moreover, the boundary between the Okote Member and the KBS Member in the Ileret region is placed at a prominent caliche which must closely approximate the age of the Okote Tuff in its type section. [Copyright &y& Elsevier]