Last Interglacial Research Articles

Stratigraphy and conditions of accumulation of the Younger Loesses (Vistulian) in the Holy Cross Mountains area, Poland

The paper presents results of studies focused on occurrence and correlation of four main horizons of Younger Loesses: Lowest Younger Loess (LMn – after Maruszczak, 2001), Lower Younger Loess (LMd), Middle Younger Loess (LMs), and Upper Younger Loess (LMg) recorded in five sections (Politów, Wąchock, Nietulisko Małe, Komorniki and Bodzechów) in the Holy Cross Mountains area. All analysed loesses were accumulated during the Vistulian Glaciation (Weichselian). The horizons were distinguished based on separating interstadial tundra soils, coupled with thermoluminescence dating, and correlated with marine oxygen-isotope stages MIS 5d−2. The Lowermost Younger Loess (LMn) covers the Nietulisko I soil complex (Jersak, 1973), developed on deposits of the Odranian Glaciation (MIS 6) and representing a forest soil of the Eemian Interglacial (MIS 5e) and the Brørup warming (MIS 5c). A thin horizon of the Oldest Younger Loess and a thin sandy horizon, both probably corresponding to the Herning cooling phase (MIS 5d) at the boundary with the Eemian Interglacial, were distinguished within this complex. Based on previously performed grain-size and heavy mineral analysis of the Upper Younger Loess (LMg) and a topographic position of the loesses in four loessy islands of diverse regional extent, accumulation of this loess in the Holy Cross Mountains area is found to have been stimulated by the western winds. The proposed model of loess accumulation takes into account the influence of the topography of the area and its geological structure.

Каменные индустрии раннего этапа среднего палеолита Юго-Восточного Дагестана

Приводятся результаты исследований среднепалеолитических комплексов памятников Дарвагчай-Залив-1 и Дарваг-чай-Залив-4, очень важных для понимания данного этапа палеолита Дагестана. В работе рассматривается палеоклиматическая обстановка в период накопления вскрытых отложений стоянок. Центральное место отведено описанию и анализу коллекций каменных артефактов. Отмечено, что археологические материалы залегали в слое палеопочвы, они претерпели минимальные пространственные перемещения в постседиментационный период. Каменный инвентарь представляет леваллуазскую технику расщепления. Орудийный набор типичен для среднего палеолита. С учетом наличия кострищ без следов конструкций и рассредоточенности археологического материала на обширной территории сделан вывод о многократном кратковременном посещении древним человеком стоянок. Время их существования на данной территории соответствует периодурисс-вюрмского (эемского, микулинского) межледниковья — 125-110 тыс. л.н. (MIS 5е). Большое внимание уделяется сопоставлению коллекций обсуждаемых объектов и близких по возрасту памятников Дагестана и Кавказа. На основе анализа всех имеющихся данных сделан вывод о том, что в настоящее время среди материалов среднепалеолитических памятников на Кавказе невозможно выявить прямые аналоги индустрий исследуемых стоянок. Вместе с тем археологические материалы стоянок Дарвагчай-Залив-1 и -4 соответствуют общему направлению развития палеолита Кавказа.

Geological evidences as a guide to OSL dating interpretation and northern occurrence of MIS 7e barrier at Southern Brazil

The chronology of Pleistocene strandplains remains a challenge to this day. The lack of reliable geochronology methods arises from the fact that ages from the Pleistocene sequences are beyond radiocarbon age limit method and, sometimes, near the saturation limits to luminescence dating on quartz, which may introduce uncertainties in the results. Also, choosing different curve fits for the dose-response curve leads to geological incoherent results. In this paper, we evaluated three approaches on curve fit equations (single saturating exponential (SSE), double saturating exponential (DSE) or the SSE + Linear (E + L). We also compared the three scenarios with geological evidences such as sedimentary structures, like plane-parallel lamination, and the presence Ophiomorpha nodosa ichnofossil at Paranaguá and Superagüi strandplains, Southern Brazil. Since geological evidences indicate deposition under wave-dominated shoreline, the comparison to Quaternary sealevel curves restricts the beach ridges deposition to high relative sealevel intervals. Our results show that, despite being mathematically consistent, DSE and E + L curve fits lead to geological inconsistent results. The luminescence results using SSE curve fit are geologically consistent and suggest the occurrence of MIS 7e barrier on Paranaguá and Superagüi strandplains, the farther north occurrence of the Barreira II (195–220 ky) correspondent to the Rio Grande do Sul strandplain. However, we stress out that luminescence dating results near the saturation limit must be interpreted with caution, and preferably supported by other evidences.

Gas Hydrate Dissociation During Sea‐Level Highstand Inferred From U/Th Dating of Seep Carbonate From the South China Sea

AbstractGas hydrates represent a huge reservoir of methane in marine sediments, prone to dissociation in response to environmental changes. There is consensus that past events of gas hydrate dissociation in the marine environment mainly occurred during periods of low sea level. Here, we report geochemical data for 2‐m‐thick layers of seep carbonate collected from a hydrate‐bearing drill core from ~800‐m water depth in the northern South China Sea. The aragonite‐rich carbonates reveal positive δ18O values, confirming a genetic link with gas hydrate dissociation. Uranium‐thorium dating of seep carbonates indicates that gas hydrates at the study site dissociated between 133,300 and 112,700 years BP, hence coinciding with the Last Interglacial (MIS 5e) sea‐level highstand. We put forward the concept that a climate‐driven increase in temperature was responsible for a period of pronounced gas hydrate dissociation.

Migration of Pleistocene shorelines across the Palaeo-Agulhas Plain: Evidence from dated sub-bottom profiles and archaeological shellfish assemblages

Intertidal zones on shorelines are geologically complex features of the coastal plain, shaped by heterogeneous substrate lithologies. Palaeocoastlines have been heavily modified by sea-level change, ocean currents, wind, waves and swell. Rocks and sediments along intertidal zones create rich habitats for biogenic forms including shellfish, which are highly sensitive to subtle variations in underlying lithology. Here, we assess Pleistocene shoreline migrations on the south coast of South Africa in relation to fluctuating sea-levels and changes in sediment supply. The study area extends from Still Bay to Mossel Bay, South Africa, with a particular focus on Pinnacle Point. Our goal is to better understand the changes to the intertidal zone along these palaeocoastlines and how this may have affected marine resources available to early humans. We interpret marine geological records at select time slices along sub-bottom profiled transects that run perpendicular to the coast. We describe the character of specific shorelines to establish expectations of coastline character which we then compare to archaeological records at Pinnacle Point. We base our interpretations on (1) significant events in Pleistocene glacio-eustatic and depositional records, such as widespread deposition of coastal sand dunes at ∼90, ∼74 and ∼50 ka [MIS 5e–MIS 4], and (2) empirical evidence from high-resolution records of shellfish assemblages at the archaeological sites of PP13B and PP5-6. We demonstrate a prevalence of dissipative beaches and mixed coasts on Pleistocene sea-level lowstands on the coast of the Palaeo-Agulhas Plain. This differs significantly from the modern coastline with its significance of rocky shorelines.

ESR and U-Th dating results for Last Interglacial coral reef terraces at the northern coast of Cuba

Fossil coral reef terraces at the northern coast of Cuba in the vicinity of the Bay of Matanzas are forming a prominent flight of terraces. These terraces were already studied by several investigators, but a chronological classification based on numerical dating is still missing. In this study we focus on the lowest unit, the Seboruco terrace, which is assumed to be of MIS 5e age. The morphology of the Seboruco terrace and associated sea-level markers (reef crests and notches) were mapped and their altitude was measured over the whole study area in the field and by using remote sensing. The fossil corals building up the terrace were surveyed in numerous natural outcrops. The species of the fossil coral reefs were determined and subdivided in different facies zones. Fossil corals were taken for numerical dating by Electron Spin Resonance (ESR) and Uranium-series (U-Th) to establish a chronology of the MIS 5e coral reef formation. Both dating techniques yielded age results in good agreement with each other and the stratigraphic context. Corresponding to the field evidence, the age data indicates one MIS 5e sea-level highstand around 126 ka. Some younger ESR ages may be explained by the recrystallization of aragonitic corals and/or by U leaching. At one locality east of Matanzas, the radiometric results for an underlying coral reef body suggest an MIS 7 age. The sea-level markers for the MIS 5e highstand range from 5.5 m a.s.l. (reef crest) to a maximum of 7 m (notches) west of the Bay of Matanzas resulting in relatively low uplift rates of 0.003 m/ka and 0.036 m/ka when applying early MIS 5e sea-level estimates from tectonically stable coasts in the Caribbean between +2.5 m and +6.6 m. Inside the Bay of Matanzas itself, the elevation of sea-level markers increases to more than 10 m a.s.l. indicating a stronger uplift rate of 0.027 m/ka to 0.060 m/ka here.

Пам'ятки середнього палеоліту в околицях Маріямполя на Дністрі

Over many years of archaeological research a number of Middle Paleolithic sites have been discovered in the vicinity of Mariampil, including Bukivna IV, Bukivna V, Yezupil I, Kolodiiv, Mariampil I, Mariampil V and others. The site of Mariampil I was discovered in the 1920s by Yu. Polanski. Since then the site has not been researched, although it is quite promising from the point of view of the Middle and Upper Palaeolithic studies in the region. In 2014, the study of the site was renewed using a number of modern methods of natural sciences. The samples were taken from the section of the site. Samples were taken every 0.2 m from the loess horizons and every 0.1 m from the Horokhiv fossil pedocomplex for granulometric analysis, general chemical analyses (humus content, Fe2O3, CaCO3). A number of samples were also taken for absolute dating of the sediments (TL, OSL), palynological research, as well as from certain horizons of the Horokhiv fossil pedocomplex for micromorphological research and analysis of biomarkers. The history of research, the geological structure and the archaeological material of Mariampil I were highlighted in the article. The association of the oldest (fourth) cultural layer, which was found by Yu. Polanski and confirmed by our fieldwork in 2014–2015, with the eluvial horizon of Horokhiv fossil pedocomplex (MIS 5e) was determined. It was dated by the OSL method at 102+16 ka BP and it correlates well with the archaeological determination of the age of the artifacts. As a result of the research, a large amount of factual material was obtained concerning the structure of the Upper Pleistocene loess-soil sequence, whose thickness is over 17 m, which is abnormally high for the Halych-Dnister region. Information about two important stratified Middle Palaeolithic sites in Ivano-Frankivsk region is also given. This is a three-layer Palaeolithic site of Yezupil I of Tysmenytsia district and Mariampil V of Halych district, which by chronological position and cultural and technological tradition are analogues of Mariampil I. Numerous Middle Palaeolithic sites in the vicinity of Mariampil on the Dnister River indicate a quite powerful centre of the Neanderthal communities in this area. Key words: Mousterian, Micoquien, Upper Palaeolithic, loess-soil sequence, Halych-Dnister region.

Significant SST differences between peak MIS5 and MIS1 along the low-latitude western North Pacific margin

The peak period of marine isotope stage 5 (MIS5e) is the most recent warm period largely comparable to the present interglacial, marine isotope stage 1 (MIS1). The spatial variations in sea surface temperature (SST) between MIS5e and MIS1 can reveal the important differences in the effects of insolation and oceanographic conditions between the two warm periods, which in turns help refine global climate models. In order to quantify the differences, this study calculated the SST for the peak periods of MIS5e (c. 128-113 ka BP) and MIS1 (c. 8-3 ka BP) along the low-latitude western North Pacific margin (18 oN to 26 oN). Together with the previously published data from the South China Sea (9 oN to 19 oN), the results indicate a generally northwards decreasing trend in the two interglacial periods. This latitudinal SST trend in both peak MIS 1 and MIS 5e can be attributed to the strong influence of ocean currents in the studied region. Secondly, the average SST of peak MIS5e is 1.3 ± 0.2 °C higher than that of peak MIS1, suggesting a higher level of insolation during the previous interglacial. However, the above general pattern is complicated by the near-shore and offshore difference in the effects of winter monsoon on oceanic conditions around 20–22 oN. The coastal upwelling near 26 oN during peak MIS5e reduced the SST, whilst the SST was raised as the upwelling ceased during peak MIS1. Finally, the SSTs of the two warm periods are significantly higher than the present SST from 20 oN northwards, implying the influence of winter monsoon cold current in the Taiwan Strait.

Makhnevskaya Ledyanaya Cave (Middle Urals, Russia): Biostratigraphical reconstruction

Pollen and fossil mammals of the terrigenous deposits in the Makhnevskaya Ledyanaya Cave (59°26′ N 57°41’ E), located in the northern part of the Middle Urals and on the border with the Northern Urals, were studied. The spore-and-pollen spectra are divided into four pollen zones. In all the spectra, pollen concentrations of tree species amount to 50–70%. The presence of pollen in thermophilic (Quercus robur-type, Tilia cordata-type, Ulmus sp., Carpinus betulus, Corylus avellana-type) and moderate boreal (Abies, Picea, Pinus, Betula, Alnus) species and a lack of any tundra flora elements indicate their interglacial nature. The following have been identified as small mammal fauna: 8 taxa of insectivorous mammals, 4 taxa of bats, 2 taxa of lagomorphs, 4 species of carnivores, 16 species of rodents, 1 species of odd-toed ungulates and 4 species of even-toed ungulates. The remains of cryoxerophilous (Dicrostonyx sp., Lasiopodomys gregalis) and steppe (Ochotona sp.) species are scarce in the studied fauna. Species typical of forests (genus Sorex, genus Craseomys, genus Myodes, Myopus schisticolor, Microtus agrestis) are dominant. Remains of Erinaceus sp., Talpa sp., Crocidura leucodon, Sciurus vulgaris, Hystrix brachyura, Dryomys nitedula, Apodemus flavicollis, Stephanorhinus kirchbergensis have been found. The morphology and dimensions of the teeth of Panthera spelaea fossilis, Hystrix brachyura, Dryomys nitedula, Arvicola amphibius, mice of genus Apodemus are described. The compositions of the palynocomplexes and mammal fauna as well as the SDQ values for m1 of Arvicola amphibius allow us to date the deposits from the Makhnevskaya Ledyanaya Cave to the Eemian interglacial period (MIS 5e).

Ocean-atmosphere interconnections from the last interglacial to the early glacial: An integration of marine and cave records in the Iberian region

This study explores the climatic variability in the Iberian Peninsula (IP) and its surrounding seas from 140 to 65 kyr BP. Marine sediment cores and cave speleothems are used to reconstruct changes in sea surface water conditions, deep sea current intensities and atmospheric moisture availability based on stable isotopes, trace elements, grain size and XRF-elemental analysis. Oxygen isotopes in both terrestrial and oceanic archives recorded a large-scale precessional climatic rhythm that suggests a common modulation. This signal is interpreted as changes of the isotopic composition in the rainwater source area that is later transmitted into the cave. In terms of millennial-scale variability, the records trace the sequence of events defined for the North Atlantic region. The marine records show an intense sea-surface freshening and cooling related to Heinrich Event 11. During the Last Interglacial (LIG), the sea surface temperature evolution was heterogeneous around the IP with gradients larger than those from today. The LIG ended earlier in the Cantabrian Sea than in the western Mediterranean Sea, which it was coincident with an accelerated aridification phase that marked the glacial inception in a Minorca speleothem at 116.5 kyr BP and preceding the GS25. This was the first of a series of stadials that punctuated the early glaciation and where the sea thermal gradient almost disappeared around the IP. These intense cooling during stadials led the development of drier but intense westerlies over southern European latitudes, reflected in a Pyrenees speleothem record, and favouring enhanced deep convection in the western Mediterranean Sea. In contrast to this stadial regional homogeneity among the studied records, the interstadials periods are distinguished by their rather heterogeneous patterns around the IP pointing to much complex ocean-atmosphere interconnections during warm intervals.

All is flux: the predictive power of fluctuating Quaternary mammalian faunal-climate scenarios.

The long-term impact of Middle and Late Pleistocene glacial-interglacial change led to the major reorganization of mammalian faunal communities in northern Europe through species origination, extinction, evolutionary change and distributional shifts. A Bray-Curtis cluster analysis with single linkage to examine relative faunal similarity was performed on mammalian assemblages from five successively older interglacials (MIS 1, 5e, 7c-a, 9 and 11) in Britain, a region with an exceptionally well-resolved faunal record for this time period. The results indicate a degree of continuity in terms of common interglacial elements occurring across all periods but also reveal that the particular climatic and environmental parameters of each interglacial resulted in the generation of very different faunal assemblages, depending on the length, intensity and structure of the interglacial. Of particular note are the comparability of the mammalian assemblages from warm interglacials MIS 5e and 9, and the high species diversity seen in MIS 7c-a, linked to relatively cool temperate conditions and the spread of dry grasslands. Together, these results offer insight into the overall 'predictability' of Quaternary mammalian interglacial community composition and what might be expected in the natural evolution of a Holocene interglacial freed of anthropogenic interference. This article is part of a discussion meeting issue 'The past is a foreign country: how much can the fossil record actually inform conservation?'

Vegetation history and environment changes since MIS 5 recorded by pollen assemblages in sediments from the western Bohai Sea, Northern China

Due to the lack of well-constrained chronology, the history of climate and vegetation associated with sea level changes during the late Quaternary has been poorly understood in the Bohai sea area. In this study, the upper 56.0 m-long sediment of the TJC-1 core in the western Bohai Sea was investigated using pollen and spore analyses, together with OSL, AMS 14C dating, grain size, and foraminifera data. The chronologically well -constrained core records show that varying pollen and spore assemblages reflect changes in vegetation on the adjacent land, climate and sediment settings since MIS 5 stage. Arboreal pollen dominated by Pinus and Quercus generally prevailed during the warm periods (MIS 5a, 5c, 5e, MIS 3 and MIS 1), corresponding to the sea level highstands, while dominance of terrestrial herbs such as Artemisia and Chenopodiaceae indicate presence of grasslands during cold periods such as MIS 4, MIS 5b and 5d when sea level dropped significantly. During the stadial periods such as MIS 5b and MIS 5d, herbaceous assemblages predominated in relatively cold conditions, in response to fluvial and coastal high energy sedimentary environments. The dominance of herbs especially Chenopodiaceae in the early-middle of MIS 5 and early Holocene was probably associated with huge amounts of sandy sediments input from the Yellow River caused by strong rainfall. Furthermore, pollen concentration is closely related to sediment grain size, arboreal pollen and fern spores are especially deposited in the fine sediment while herbaceous pollen dominates in coarser sediment.

Multiproxy evidence of middle and Late Pleistocene environmental changes in the loess-paleosol sequence of Bůhzdař (Czech Republic)

Loess-paleosol sequences preserve information that can be used to reconstruct paleoenvironments. A dense network of reliably analyzed sequences from different geographic locations is crucial to address ecological and climatic trends, which occurred during the Pleistocene. This paper focuses on a loess-paleosol sequence in Bůhzdař, situated 9 km NW of Prague, Czech Republic. Geochemical approaches (total organic carbon, XRF elemental analyses, XRD mineralogy, 13C and 18O stable isotopes) are combined with grain-size distributions and optically stimulated luminescence (OSL) to assess the climatic conditions at the time of formation of the strata. The oldest loess at this location was formed circa 200 ka ago (MIS 7), making it the oldest loess in Central Bohemia for now. The Bůhzdař loess-paleosol sequence was highly affected by several erosion events, Eemian paleosols (MIS 5e) being completely missing. The partly relocated paleosols situated at the lower part of the Bůhzdař sequence represent a period of increased humidity during late MIS 7 and MIS 6. Despite the fact that the Bůhzdař profile is not particularly thick (5 m), significant changes in paleoclimate reconstructions have been detected.

A look into the past, present and future potential distributions of Talinopsis frutescens, a North American endemic lineage closely related to Cactaceae

Talinopsis frutescens (Anacampserotaceae, a family that is close related to Cactaceae) is a succulent species endemic to North America. The aim of this study was to explore, using Ecological Niche Modeling (ENM), changes in potential distribution ranges considering different climate scenarios: past conditions during the Last Inter Glacial (LIG) and the Last Glacial Maximum (LGM), the present and projections for 2070 (RCP 2.6 to 8.5). A pattern of contraction is observed during the LIG, which agrees with other studies focused in species from arid environments. This pattern was followed by a migration towards the south during the LGM and a possible recent expansion to the north as is observed in the present scenario. All future projections show the same contraction and fragmentation patterns, resulting in three discontinuous areas: the northern part of the Chihuahuan Desert, the southern-central part of the Mexican Plateau, and the smallest one in the Tehuacan-Cuicatlan Valley. Our projections for future scenarios agree with other studies and support that global climate change tends to alter the current distribution of arid environment species.

An ecological barrier between the Himalayas and the Hengduan Mountains maintains the disjunct distribution of Roscoea

AbstractAimRegional disjunction in mountainous regions is ubiquitous and is closely associated with the evolution of mountain biodiversity. However, the mechanisms of maintaining regional disjunction are often ignored, especially regarding the role of ecological barriers. The aim of this study is to test whether an ecological barrier maintains the regional disjunction of Roscoea between the Himalayas (HIM) and the Hengduan Mountains/Yun‐Gui Plateau (HMY).LocationThe Himalayas and the Hengduan Mountains/Yun‐Gui Plateau, Asia.TaxonMonocot:Zingiberales:Zingiberaceae:Roscoea.MethodsOccurrence data from Roscoea were collected from public databases and field investigations. Environmental niche modelling (ENM) was used to predict the potential distribution of Roscoea during the Last Interglacial (LIG), the Last Glacial Maximum (LGM), the present and the future. An environmental variable difference test, principal component analysis (PCA), discriminant function analysis (DFA) and niche identity test were employed to qualify and quantify the contributions of environmental factors to ecological divergence based on 7 and 26 environmental variables.ResultsEnvironmental niche modelling predicted an ecological gap of Roscoea between the HIM and the HMY from the LIG into the future, excluding the LGM. Statistically significant differences were detected in eight unique environmental variables across the Gap, which was mostly related to low temperatures and high moisture levels. The PCA, DFA and niche identity test suggested larger ecological separations among the Gap, the HIM and the HMY based on 26 environmental variables than based on seven variables.Main conclusionsAll clues point to an ecological barrier that has been maintaining the regional disjunction of Roscoea. This ecological barrier is predicted to be stable under future climate change and may reflect long‐term ecological divergence shaped by the adaptation of Roscoea to divergent habitats. Our study highlights that the effects of specific environmental variables, with possible interactions among multiple ecological factors, being closely related to the ecological barrier.

A strong east–west Mediterranean divergence supports a new phylogeographic history of the carob tree (Ceratonia siliqua, Leguminosae) and multiple domestications from native populations

AbstractAimPhylogeography of fruit trees is challenging due to recurrent exchanges between domesticated and wild populations. Here we tested the eastern refugium hypothesis (ERH) for the carob tree, Ceratonia siliqua, which supports its natural and domestication origins in the eastern Mediterranean and a feral origin in the west.LocationMediterranean basin.TaxonCeratonia siliqua L., Leguminosae.MethodsA phylogenetic reconstruction based on two nuclear and one plastid sequences was performed to estimate the divergence time between the carob tree and its sister species, Ceratonia oreothauma. Variation from four plastid regions and 17 nuclear microsatellite loci were used to decipher genetic structure in the carob tree and to test coalescent‐based models by an Approximate Bayesian computation (ABC) approach. We assessed our hypotheses by examining palaeobotanical records and hindcasting the past distribution of the carob tree at Mid‐Holocene, Last Glacial Maximum (LGM) and Last Interglacial (LIG) using species distribution modelling.ResultsThe split between C. oreothauma and C. siliqua was estimated at 6.4 Ma, and a first divergence within C. siliqua at 1.3 Ma. After a continuous presence since the Oligocene, Ceratonia was rarely found in the fossil record during the Pleistocene but present in the western and the eastern Mediterranean. Plastid and nuclear markers, characterized by low allelic richness, revealed a strong west‐east genetic structuring. ABC analyses rejected the ERH.Main conclusionsOur study supports a severe population decline during LIG. The strong west–east divergence and the occurrence of four lineages within C. siliqua provided support for a new hypothesis of multiple domestications of the carob tree from native populations throughout the Mediterranean basin.

Morphology of fore-reef slopes and terraces, Takapoto Atoll (Tuamotu Archipelago, French Polynesia, central Pacific): The tectonic, sea-level and coral-growth control

A dataset of 41 bathymetric profiles detected by satelline imagery and echo-sounding to a maximum depth of 38 m along the fore-reef slopes of Takapoto Atoll (Tuamotu Plateau, French Polynesia, central Pacific) were qualitatively and quantitatively analyzed in order to identify the main geomorphological features. In addition, scuba-diving investigations from a selected site resulted in defining coral composition and cover rate. Six distinct fore-reef sectors were morphologically differentiated on the basis of seaward extension and slope gradient. Only the north end, and a restricted area of the mid-south-east side extend seawards over an average distance of 150 m, with a relatively low gradient (23°–38°). Most of the outer-slope areas are narrow (<100 m on average) and steep (average slope equals to 45° to up to 70°). Geomorphic features include spur-and-groove systems, sub-horizontal to gently dipping terraces (23–45 m wide) ending seawards in vertical steps (<10 m high) and drop-offs (>10 m high), outer-reef crest-like reliefs (0.5 m–1.5 m high), pinnacles (2 m–17 m high), coral heads (<2 m high), trenchs and concave scars. The recognized seven terrace levels occur at the respective depths of about −5 m, −10 m, −15 m, −20 m, −24 m, −30.5 m and −38 m. Based on comparison with subsurface chronostratigraphy of drilled reef sequences from some other Pacific atolls, the terraces are interpreted as remnants of reef tracts formed during Pleistocene interglacial, high sea-stands, respectively during MIS substage 5e (about −125 ka), MIS substages 7a (about −195 ka), 7c (about −210 ka), 7e (about −240 ka) and 9e (−330 ka). After depth correction of ground lowering during periods of emergence and subsidence effects, terrace elevations were expected to indicate eustatic sea-level positions at each identified high sea-stand, at approximately 7 m (MIS 5e) and 2.2 m (MIS 7a) above present sea level and 9.5 m (MIS 7c), 11 m (MIS 7e) and 8.6 m (MIS 9e) below present sea level. During the post-glacial sea-level rise, from about 9.5 ky, the studied portions of fore-reef slopes were re-flooded. It was assumed that coralgal deposits in the form of thin veneers, coral heads, outer-reef crest-like reliefs and pinnacles have simply overlapped pre-existing structures. Locally, the fore-reef zones are carved by trenchs, i.e. incipient detachment faults, and scars, i.e. imprints of former landslides. Similarly, some drop-offs may be regarded as fault walls. The prevailing direction of faulting–collapsing surfaces is consistent with the SW–NE orientation of the main axis of the atoll and submarine ridges rising up from the north-western floor of the Tuamotu Plateau. Analysis of the composition and distribution of coral communities to −30 m depth revealed high, downslope-increasing coral coverage (24% to 67% on average) and the sharp replacement of robust-encrusting Pocillopora by sub-massive to plate-like Porites from depths greater than −10 m. Significant inter-regional differences were detected with atolls in west Pacific, probably due to local ecological constraints.

Last Interglacial Climate in Northern Sweden—Insights from a Speleothem Record

Continental records with absolute dates of the timing and progression of climatic conditions during the Last Interglacial (LIG) from northern Europe are rare. Speleothems from northern Europe have a large potential as archives for LIG environmental conditions since they were formed in sheltered environments and may be preserved beneath ice sheets. Here, we present δ13C and δ18O values from speleothem Kf-21, from Korallgrottan in Jämtland (northwest Sweden). Kf-21 is dated with five MC-ICPMS U-Th dates with errors smaller than ~1 ka. Kf-21 started forming at ~130.2 ka and the main growth phase with relatively constant growth rates lasted from 127.3 ka to 124.4 ka, after which calcite formation ceased. Both δ13C and δ18O show rapid shifts but also trends, with a range of values within their Holocene counterparts from Korallgrottan. Our results indicate an early onset of the LIG in northern Europe with ice-free conditions at ~130 ka. Higher growth rates combined with more negative δ18O values between ~127.3 and 126.8 ka, interpreted here as warmer and more humid conditions, as well as indications of a millennial-scale cold spell centered at 126.2 ka, resemble findings from speleothem records from other parts of Europe, highlighting that these were regional scale climatic patterns.

The foraging potential of the Holocene Cape south coast of South Africa without the Palaeo-Agulhas Plain

The Palaeo-Agulhas Plain formed an important habitat exploited by Pleistocene hunter-gatherer populations during periods of lower sea level. This productive, grassy habitat would have supported numerous large-bodied ungulates accessible to a population of skilled hunters with the right hunting technology. It also provided a potentially rich location for plant food collection, and along its shores a coastline that moved with the rise and fall of sea levels. The rich archaeological and paleontological records of Pleistocene sites along the modern Cape south coast of South Africa, which would have overlooked the Palaeo-Agulhas Plain during Pleistocene times of lower sea level, provides a paleoarchive of this extinct ecosystem. In this paper, we present a first order illustration of the “palaeoscape modeling” approach advocated by Marean et al. (2015). We use a resourcescape model created from modern studies of habitat productivity without the Palaeo-Agulhas Plain. This is equivalent to predominant Holocene conditions before recent landscape modifications for farming. We then run an agent-based model of the human foraging system to investigate several research questions. Our agent-based approach uses the theoretical framework of optimal foraging theory to model human foraging decisions designed to optimize the net caloric gains within a complex landscape of spatially and temporally variable resources. We find that during the high sea-levels of MIS 5e (+5–6 m asl) and the Holocene, the absence of the Plain left a relatively poor food base supporting a much smaller population relying heavily on edible plant resources from the current Cape flora. Despite high species diversity of plants with edible storage organs, and marine invertebrates, encounter rates with highly profitable resources were low. We demonstrate that without the Palaeo-Agulhas Plain, human populations must have been small and low-density, and exploited plant, mammal, and marine resources with relatively low caloric returns. The exposure and contraction of the Palaeo-Agulhas Plain was likely the single biggest driver of behavioural change during periods of climate change through the Pleistocene and into the transition to the Holocene.

Cryptic phylogeographic history sheds light on the generation of species diversity in sky‐island mountains

AbstractAimThe aim of this study was to conduct comprehensive phylogeographic and demographic analyses to examine the degree to which topographic and climatic conditions have affected the patterns of diversification and migration in a strictly montane inhabitant, the montane long‐tailed mole (Scaptonyx fusicaudus).LocationThe mountains of south‐western China and adjacent mountains including Mts. Bashan, Dalou and Qinling also known as the sky islands in south‐western China.TaxonThe long‐tailed mole (S. fusicaudus), a semi‐fossorial mammal distributed in the sky islands of south‐western China, is a relict species and the sole representative of the tribe Scaptonychini.MethodsWe sequenced one mitochondrial and six nuclear genes from 113 samples across the species’ range. We estimated phylogenetic relationships and divergence times, conducted genetic structuring and species delimitation using multiple approaches and used Approximate Bayesian Computation to test potential gene flow. We conducted ecological niche modelling to predict the species’ potential distribution in the present, the last glacial maximum and the last interglacial (LIG).ResultsThe species comprises a minimum of 17 operational taxonomic units which are isolated in different mountain ranges. The lowlands and large rivers act as barriers to dispersal, and have isolated evolutionary lineages for up to 11 million years. Long‐distance dispersal is evident among a few discrete montane archipelagos. Suitable climatic conditions during the LIG are limited to only a few sites, thus geographically restricting climatic stable areas across geological periods (from the LIG to the present).Main conclusionsFor low‐vagility species, the complex topography of the sky islands has promoted exceptional diversification through a combination of eco‐environmental stability as well as geographic fragmentation. The mountains have acted as a buffer against climate change, and have provided continuously suitable habitats for S. fusicaudus since the early Late Miocene, supporting the hypothesis that the sky islands constitute “museums” of ancient lineages. Lowlands and river valleys have acted as barriers preventing gene flow, while the montane archipelagos could have provided stepping stones to facilitate dispersal.