Recent Record Research Articles

Late Holocene record of subantarctic glacier variability in Table Fjord, Cook Ice Cap, Kerguelen Islands

The subantarctic islands between 40 and 60°S are circum-polar landmasses influenced by the southern westerly wind (SWW) belt whose latitudinal shifts are driven by the Southern Annular Mode (SAM) over decadal timescales. In the Indian sector of the Southern Ocean, the Kerguelen Islands (49°S) form a volcanic archipelago that is home to the Cook Ice Cap (CIC). Atmospheric drying favored by a poleward migration of the SWW induced a dramatic shrinkage of the CIC over the past 50 years. Current knowledge of how this decline compares with the natural variability of the CIC is unclear and based exclusively on geomorphological records with limited temporal resolution. This paper introduces a 4 kyr marine record built from a transect of giant piston cores collected in Table Fjord, southwestern margin of the CIC. Interpretation of sedimentary and geochemical proxies is supported by statistical correlations with the CIC surface mass balance on the instrumental timescale, and by the age overlapping with dated landforms and deposits over the last two millennia. High-resolution geochronological data (137Cs and 210Pb inventories along with 63 AMS 14C dates) corrected from a local marine reservoir age allowed reconstructing glacier variability at a multidecadal resolution. The CIC was paced by periods of glacial advances at 3.4–2.8, 2.3–1.7, and 1.35–1.15 ka cal BP, followed by a two-stage ‘Little Ice Age’ maximum between 0.7 ka cal BP and the early 20th century. Comparison with paleoenvironmental records from the subantarctic fringe zone and the southern mid-latitudes suggests SWW-driven precipitation (wetter and windier conditions) were the main driver of centennial-scale glacier variability in the Kerguelen Islands, notably after 2.3 ka cal BP. The Kerguelen record thereby supports a zonally-synchronous, hemispheric-wide SWW pattern pacing Southern Ocean climatic variability in a SAM-like mode. The Little Ice Age maximum ice extent results from the coincidence of cold conditions caused by an equatorward shift of the Polar Front, an oceanic front bordering the Kerguelen archipelago resulting in lower sea surface temperatures, together with wetter conditions favored by strengthened SWW.

Post-glacial stratigraphy and late Holocene record of great Cascadia earthquakes in Ozette Lake, Washington, USA

Ozette Lake is an ~100-m-deep coastal lake located along the outer coast of the Olympic Peninsula (Washington, USA); it is situated above the locked portion of the northern Cascadia megathrust but also relatively isolated from active crustal faults and intraslab earthquakes. Here we present a suite of geophysical and geological evidence for earthquake-triggered mass transport deposits (MTDs) and related turbidite deposition in Ozette Lake since ca. 14 ka. Comprehensive high-resolution bathymetry data, seismic reflection profiles, and sediment cores are used to characterize the post-glacial stratigraphic framework and examine paleoseismic evidence in the lacustrine sediments. Stacked sequences of MTDs along the steep eastern flanks of the lake appear to grade basin-ward from thick, chaotic, blocky masses to thin, parallel-bedded turbidite beds. The discrete turbidite event layers are separated by fine-grained (silt and clay) lake sedimentation. The event layers are observed throughout the lake, but the physical characteristics of the deposits vary considerably depending on proximity to primary depocenters, steep slopes, and subaqueous deltas. A total of 30–34 event deposits are observed in the post-glacial record. Radiometric dating was used to reconstruct a detailed sedimentation history over the last ~5.5 k.y., develop an age model, and estimate the recurrence (365–405 yr) for the most recent 12 event layers. Based on sedimentological characteristics, temporal overlap with other regional paleoseismic chronologies, and recurrence estimates, at least 10 of the dated event layers appear to be sourced from slope failures triggered by intense shaking during megathrust ruptures; the recurrence interval for these 10 events is 440–560 yr. Thus, Ozette Lake contains one of the longest and most robust geological records of repeated shaking along the northern Cascadia subduction zone.

Holocene biogeography of the southwestern European white‐toothed shrew (Crocidura iculisma, Eulipotyphla) through its fossil record

Abstract Crocidura iculisma (=C. suaveolens) is a shrew (Soricidae, Eulipotyphla) showing a fragmented distribution limited to the Iberian Peninsula, southern and western France and northwestern Italy. Although it has been in the Iberian Peninsula since the Middle Pleistocene, its biogeographical history remains poorly known. Here, we provide new data on Crocidura iculisma from the Castillejo del Bonete site (southern Spain) dated as 3.8–3.6 cal kyr BP. At the same time, we analyse changes in its geographic distribution based on its palaeontological record. We have reviewed thoroughly the Holocene record of Crocidura iculisma in southwestern Europe, considering independently the three time intervals according to the stages defined for this geological time series (Greenlandian, Northgrippian and Meghalayan). Whenever found together in fossil sites, the relative abundance of the two sympatric shrews of the genus Crocidura (Crocidura russula and Crocidura iculisma) was analysed. The data obtained concerning past distribution range and relative abundance were compared with the current status of the species in Iberia to interpret changes through time. The distribution range of the southwestern European white‐toothed shrew in the Iberian Peninsula has notably reduced over time until today. The occurrence at Castillejo del Bonete and other palaeontological records located beyond its current distribution range show that it was distributed in several areas of the eastern part and southern interior of Iberia, at least until the second half of the Meghalayan. Relative abundance patterns observed in the fossil assemblages suggest that competitive exclusion by Crocidura russula and climatic changes played a crucial role in driving the extirpation of Crocidura iculisma from a substantial portion of the Iberian Peninsula.

Southward shift of the westerly jet intensified late Holocene dust storms on the Tibetan Plateau

The climate change on the Tibetan Plateau (TP) exhibits a north-south dipole trend during the Holocene. However, it is unclear whether regional differences exist in the variations and driving mechanisms of dust storm activities across the entire TP, and whether these mechanisms align with those found in monsoonal northern China. Here, we present a high-resolution Holocene record of dust storms from an undisturbed lake in the research gap area of the TP, and compile previously published records from other TP regions. Our findings indicate that the dust storm activity increased from the early Holocene to the late Holocene, peaking after 5 cal ka BP. Importantly, our comparison with other dust storm records reveals a unified intensification of dust storm activity across the entire TP during the late Holocene, a pattern distinctly different from the north-south dipole trend of precipitation variation. Moreover, this unified pattern of dust storm intensification across the TP cannot be explained by the decreasing intensity of the East Asian winter monsoon (EAWM) during the Holocene. The observations suggested a limited role for precipitation and EAWM in modulating TP dust storms on the millennial timescale during this period. By contrast, the increases in dust storms on the TP after 5 cal ka BP correlates well to the southward shift of the westerly jet driven by the North Atlantic Oscillation (NAO). As the NAO transitioned to a negative phase during the late Holocene, a meandering westerly jet shifted southward to the interior of the TP, intensifying wind intensity and leading to dust storm outbreaks.

Tropical forcing and ENSO dominate Holocene climates in South Africa's southern Cape

This paper explores the Holocene climatic dynamics of South Africa's southern Cape, a region that supports a large proportion of the Greater Cape Floristic Region and contains an array of important archaeological sites. While South African climates are generally characterised by marked rainfall seasonality, the southern Cape is currently situated at the interface between tropical and temperate climate systems, resulting in a largely aseasonal rainfall regime. This regime, however, is thought to have been particularly sensitive to past changes in late Quaternary boundary conditions, meaning that variability in either tropical or temperate systems could have significant environmental impacts. Evidence of past climate change, however, remains limited.We present a 9000-year record of hydroclimatic variability obtained from rock hyrax midden stable nitrogen records, from Papkuilsfontein, on the southern slope of the Anysberg Mountains. Resolved to an average 6-year resolution and spanning the period c. 9050 cal yr BP to 1990 CE, this is the highest resolution Holocene record from southern Africa and presents a unique opportunity for the detailed study of the primary drivers and spatial gradients of Holocene climate change in the southern Cape. The data indicate a long-term decrease in aridity across the Holocene and a pattern of variability that reveals remarkable similarities with records from the South African tropics and El Niño–Southern Oscillation proxies, highlighting the significance of tropical systems as drivers of Holocene climate change in the region. This substantially expands what has been previously considered to be the zone of tropical influence, extending from a coastal phenomenon associated with heat transport via the Agulhas Current to encompass much, if not all, of the Agulhas Plain south of the Cape Fold Mountains. These findings provide a valuable new climatic framework for contextualizing changes in ecological and archaeological records in the southern Cape, and contribute to a more comprehensive understanding of the spatio-temporal dynamics of climate systems in southern Africa.

Zonal control on Holocene precipitation in northwestern Madagascar based on a stalagmite from Anjohibe

The Malagasy Summer Monsoon is an important part of the larger Indian Ocean and tropical monsoon region. As the effects of global warming play out, changes to precipitation in Madagascar will have important ramifications for the Malagasy people. To help understand how precipitation responds to climate changes we present a long-term Holocene speleothem record from Anjohibe, part of the Andranoboka cave system in northwestern Madagascar. To date, it is the most complete Holocene record from this region and sheds light on the nature of millennial and centennial precipitation changes in this region. We find that over the Holocene, precipitation in northwestern Madagascar is actually in phase with the Northern Hemisphere Asian monsoon on multi-millennial scales, but that during some shorter centennial-scale events such as the 8.2 ka event, Anjohibe exhibits an antiphase precipitation signal to the Northern Hemisphere. The ultimate driver of precipitation changes across the Holocene does not appear to be the meridional migration of the monsoon. Instead, zonal sea surface temperature gradients in the Indian Ocean seem to play a primary role in precipitation changes in northwestern Madagascar.

A new extinct desert rodent from the Holocene of South America and its bearing on the diversity of Octodontidae (Hystricognathi)

Abstract A Late Holocene (ca. 3,100 to 380 BP) sample of the viscacha rat genus Octomys (Octodontidae) from the Vaquerías Gruta 1 site (VQ-G1) in western Argentina is reported. Phylogenetic and morphometric comparative analyses with living octodontids support that the VQ-G1 sample is related to the desert specialists Tympanoctomys and Octomys, and is sister to the only living species of the latter, O. mimax. The estimated morphological distance to O. mimax is greater than that between pairs of congeneric octodontid species, and even greater than that between some species belonging to different genera. This suggests that the sample represents a new species, whose young age prevents interpreting it as an anagenetic ancestor of O. mimax. If the new species is the result of cladogenesis, its absence in the current fauna represents actual extinction, which among caviomorphs is added to those of †Clyomys riograndensis, †Dicolpomys fossor, †Ctenomys viarapaensis, and †Galea tixiensis—also extinct in the Late Holocene. Thus, the VQ-G1 sample provides evidence of changes in diversity and distribution undergone by small mammals in southern South America during that time. The potential contribution of the Holocene record may be key to elucidate this issue from both an evolutionary and a conservation perspective. This requires a detailed systematic approach to determine whether the taxa under study are truly independent evolutionary units, as well as geographically broad sampling efforts to distinguish the changes affecting distribution from those producing irreversible changes in diversity.

NZPSV11k.2023 and NZPSV1k.2023: Holocene palaeomagnetic secular variation master records for New Zealand

The southwest Pacific region represents a large area of the globe that is under-represented in palaeomagnetic secular variation databases. Reliable data from the region are however crucial in constructing reliable global models and master records that can be used for palaeomagnetic and archaeomagnetic dating. NZPSV11k.2023 and NZPSV1k.2023 are the result of many years of work during which the palaeomagnetic records and age control of several sequences of lacustrine sediments have been developed and refined, and during which volcanic and archaeomagnetic records have been collected. The New Zealand Holocene record presented here, NZPSV11k, combines continuous records of declination and inclination from multiple sediment cores from each of three lakes, each sequence being independently dated by radiocarbon estimates and/or tephrochronology. The relative palaeointensity record from one of the lakes has been calibrated and added. All records are referenced to 40°S, 175°E. The resulting record differs significantly from the predictions of global models that do not incorporate data from the region. NZPSV11k shows periods of regular, but aperiodic, moderate amplitude directional swings between 11,250 and 8000 BP and between 4000 BP and the present, but lower amplitude variations during the interim 4000 years. NZPSV1k is a separate, high-resolution, full-vector record covering the past millennium. It combines data from the New Zealand geomagnetic observatory, calculations from the gufm1 model, lake sediment data and palaeointensities from archaeological hāngī (Māori earth oven) stones.It is recommended that the three individual lake sediment records are incorporated separately in future global models of the geomagnetic field, while NZPSV11k and NZPSV1k will be valuable in dating Holocene and recent materials carrying a palaeomagnetic direction and/or intensity.

Characterizing Archaeological Rhyolites in the Nenana Valley, Interior Alaska

Portable X-ray fluorescence (pXRF) is a useful geochemical technique employed to explore toolstone procurement strategies in the lithic record, commonly utilized in sourcing obsidians. Non-obsidian volcanic toolstones (e.g., dacites, rhyolites, basalts, and andesites) are abundant in interior Alaskan assemblages yet understudied compared to obsidian. Geochemical analyses of these non-obsidian materials offer the potential to gain new insights into ancient toolstone provisioning behaviors. This paper presents a synthesis of geochemical (pXRF) analyses of rhyolite artifacts, systematic regional raw material surveys, and lithic technological analyses collected from nineteen late Pleistocene and Holocene assemblages from the Nenana valley, interior Alaska. Previous research studies on archaeological rhyolites from the region are replicated, new rhyolite artifact groups are identified, and one new rhyolite source is reported and described here. Ultimately, this paper contributes to a growing body of geochemical research seeking to provide a more nuanced look at the complex late Pleistocene and Holocene record of eastern Beringia.

Holocene relative sea-level changes on the southern east coast of the Yellow Sea

Projections indicate increasing coastal hazards in the Yellow Sea region owing to relative sea-level rise. Accordingly, regional studies of such change over the Holocene timescale could be helpful in mitigating these threats. Here, we describe the Holocene record of relative sea-level change in the Gochang-Yeonggwang area of South Korea. We compared this record with that of other sites around the coast of the Yellow Sea, including Bohai Bay (China), the Tando Estuary and Gunsan Bay (South Korea), and sites on the east coast of the South Sea and Toyo-oka Basin, Japan. The findings are based on a multi-proxy study, including lithostratigraphy combined with radiocarbon dating and analyses of grain size distribution, magnetic susceptibility, and geochemistry, which facilitated the generation of 89 paleo-sea-level points reconstructed from 28 borehole cores. The early Holocene transgression was found to start later at Gochang-Yeonggwang than at Gunsan Bay, although the distance between them is only 150 km. This result was inferred from substantial differences in sediment delivery owing to Holocene differences in river basin size, topography, and tectonic context. Before ∼7 ka, the slope and highstands from the predicted mean sea-level models at Bohai Bay, Tando Estuary, and Gochang-Yeonggwang were steeper and lower, respectively, from north to south in the Yellow Sea, approaching the slope of the glacio-eustatic sea-level curve. Therefore, the levering effect of transgression in the early Holocene decreased southward in the Yellow Sea. The slight fluctuation in mean sea-level points of the late Holocene resulted from the formation of storm deposit layers in the coastal area, erosion and redeposition in the channel, and geomorphic effects. A partial difference occurred between the relative sea levels at Gochang-Yeonggwang and Toyo-oka. Future relative sea-level research at the southernmost part of the east coast of the Yellow Sea would further improve understanding of the coastal evolution of the region.

TAPHONOMIC INDICATORS OF DEAD OCEAN QUAHOG (ARCTICA ISLANDICA) SHELL AGE IN THE DEATH ASSEMBLAGE OF THE MID-ATLANTIC BIGHT CONTINENTAL SHELF

ABSTRACT Taphonomic indicators are often used to assess time-since-death of skeletal remains. These indicators frequently have limited accuracy, resulting in the reliance of other methodologies to age remains. Arctica islandica, commonly known as the ocean quahog, is a relatively widespread bivalve in the North Atlantic, with an extended lifespan that often exceeds two hundred years; hence, their shells are often studied to evaluate climate change over time. This report evaluates taphonomic age using 117 A. islandica shells collected from the Mid-Atlantic Bight offshore of the Delmarva Peninsula with radiocarbon dates extending from 60–4,400 cal years BP. These shells had varying degrees of taphonomic alteration produced by discoloration and degradation of periostracum. To determine if a relationship exists between taphonomic condition and time-since-death, radiocarbon ages were compared with the amount of remaining periostracum and type of discoloration. Old shells (individuals that died long ago) were discolored orange with no periostracum while younger shells (individuals that died more recently) had their original color, with some periostracum. Both the disappearance of periostracum and appearance of discoloration followed a logistic process, with 50% of shells devoid of periostracum and 50% discolored in about 1,000 years. The logistic form of long-term taphonomic processes degrading shell condition is first reported here, as are the longest time series for taphonomic processes in death assemblages within the Holocene record. This relationship can be utilized for triage when deciding what shells to age from time-averaged assemblages, permitting more efficient application of expensive methods of aging such as radiocarbon dating.

Middle to late Holocene lake level changes of Lake Sevan (Armenia) – Evidence from macro and micro plant remains of Tsovinar-1 peat section

In the Caucasus, peat deposits exposed near Lake Sevan (Armenia) provide a Middle to Late Holocene record of lake level fluctuations. The Tsovinar-1 section at the southern shore of Lake Sevan in the Armenian Highlands reveals a well-dated and divers pollen and carpo-flora covering a time span from 6000 BC to 900 AD. The abundances of pollen of forest taxa in relation to steppe vegetation indicate climatic changes through time. In parallel, the presence and number of fossils of aquatic and wetland plants, both in micro and macro floras, provide information about the presence of water and allows estimating changes of water depth. Characteristic taxa pointing to deeper water at Tsovinar-1 are Myriophyllum sp., Ceratophyllum demersum, and several species of Potamogeton. In shallow water, Persicaria amphibia,Sparganium sp., and Typha sp. dominate. In fluctuating water and wetlands those plants are replaced by Menyanthes trifoliata, Ceratophyllum submersum, Alisma sp., and others. High lake levels can be inferred at 6000−5000 BC, 1700−900 BC and 200−900 AD and are associated with humid climate and the development of forest vegetation. Low lake levels occurred at 4000−2600 BC and 600 BC−100 AD corresponding to epochs of decreased humidity and expanded steppe vegetation. Macro and micro remains of plants from the Tsovinar-1 site serve as reliable sources of information for determining environmental changes over time, which are in accordance with archaeological data from the region showing the effects of lake level changes on human activities․

Anthropogenic impact on erosion, pedogenesis and fluvial processes in the central European landscapes of the eastern Harz mountains forelands (Germany)

The Holocene development of soils and sediments at three sites in the eastern Harz foreland was investigated using field and laboratory methods and integrated into the regional Holocene record of this central European landscape.Apart from early Holocene processes, the history of mid-to late Holocene slope erosion was found to be closely linked to the local land-use history. By c. 1000 BP, soil erosion is a process that is detectable throughout the study area.The studied Chernozemic soils that now cover large areas of the studied landscape are of varying Holocene age. Linear radiocarbon age-depth relations of soil organic matter and indicative changes in soil mineral composition suggest that the Chernozem was formed by long-lasting anecic earthworm cast accumulation at the soil surface. Persistent periods of landscape openness maintained by local preindustrial agriculture explain the promotion of anecic earthworms in naturally forested landscapes of central Europe and act as temporally transgressive drivers of landscape change.An early to mid-Holocene phase of reduced fluvial activity was followed by the onset of Holocene flooding, which correlates with the onset of mining in the Harz Mountains around ca. 3000 BP (e.g. Helme). The onset of flooding of the small streams Zapfenbach and Liethe coincided with the documented medieval and modern mining phases in the eastern Harz. At all sites, present-day flooding frequencies are higher than during the early to mid-Holocene. Shifts in river system behaviour attributable to anthropogenic activities in the Harz Mountains are therefore considered another Anthropocene marker.Based on our observations, we propose that land-use-induced alteration of central European low Mountain rivers and the formation of Holocene Chernozems in subhumid central Europe, in addition to anthropogenic-induced Holocene soil erosion, are included in the cadastre of early Anthropocene processes. These processes have left distinct traces in the continental geologic record. Thus, they would support arguments for long-term time transgressive anthropogenic transformation of Earth surface systems. However, the tipping points for these processes are dated differently (soil erosion - ca. 1000 BP, river activity - ca. 3000 BP, Chernozem formation - diachronous since the Neolithic) and are closely linked to local and regional land use history. Thus, our results are another example that the definition of “golden spikes” remains a critical undertaking, especially for the beginning of the Anthropocene.

Reconstruction of Dead Sea lake level and mass balance back to 237 ka BP using halite fluid inclusions

The lake level of the Dead Sea, Southern Levant, has fluctuated with an amplitude of ∼250 m in response to the last glacial-interglacial cycle. This exceptional sensitivity to climate change, and the availability of long sedimentary archives, make the Dead Sea a benchmark for long quantitative paleohydrological reconstructions. However, discontinuities and chronological uncertainties in the marginal sedimentary record have hampered the reconstruction of Dead Sea lake levels beyond the Last Glacial (70–14 ka before present, BP). Here, we apply a two-pronged methodology. First, we measure the lake water density along ICDP deep core 5017-1-A using a new method, Brillouin spectroscopy on two-phase halite fluid inclusions; we combine it with the composition of pore water and the thickness of halite layers in the core to reconstruct lake level, volume, mass balance and subsidence rate. Second, we tune the chronology of lake levels from outcrops by matching it to the chronology of the deep core. The resulting lake level reconstruction, spanning 237–70 ka BP, is validated by the excellent agreement between outcrop- and mass balance-based methodologies. It shows a long-term recession of the lake, its level decreasing from one interglacial to the other, down to a Holocene record low. There are two reasons for this lake level fall. First, with an average rate of 2.65 ± 0.15 m/ka, subsidence has outpaced sedimentation at least over the last ∼130 ka. Second, by reducing the solute inventory of the lake, massive halite precipitation events such as that of 131–116 ka BP have durably increased surface water activity and evaporation, and thus lowered the lake level, up to today. Conversely, our analysis suggests that, during 191–11 ka BP, the dissolution of Mount Sedom salt diapir and freshwater inflows provided to the lake about three times the mass of solute NaCl contained in the modern Dead Sea (in 1985). This massive solute influx, occurring mainly during glacial highstands, strongly contributed to lowering surface water activity and evaporation and, therefore, to increasing the lake volume. Our results suggest that Dead Sea lake levels are more accurately interpreted in terms of climatic change if surface water activity is taken into account.

Early human impact on lake cyanobacteria revealed by a Holocene record of sedimentary ancient DNA

Sedimentary DNA-based studies revealed the effects of human activity on lake cyanobacteria communities over the last centuries, yet we continue to lack information over longer timescales. Here, we apply high-resolution molecular analyses on sedimentary ancient DNA to reconstruct the history of cyanobacteria throughout the Holocene in a lake in north-eastern Germany. We find a substantial increase in cyanobacteria abundance coinciding with deforestation during the early Bronze Age around 4000 years ago, suggesting increased nutrient supply to the lake by local communities settling on the lakeshore. The next substantial human-driven increase in cyanobacteria abundance occurred only about a century ago due to intensified agricultural fertilisation which caused the dominance of potentially toxic taxa (e.g., Aphanizomenon). Our study provides evidence that humans began to locally impact lake ecology much earlier than previously assumed. Consequently, managing aquatic systems today requires awareness of the legacy of human influence dating back potentially several millennia.

Coastal switching of dominant depositional processes driven by decreasing rates of Holocene sea-level rise along the macrotidal coast of Gochang, SW Korea

ABSTRACTDecreasing rates of eustatic sea-level rise during the Holocene accompanied the deposition of transgressive coastal deposits worldwide. However, unraveling how transgressive deposition varies in response to different rates of relative sea-level (RSL) rise is limited by the scarcity of long (10+ m) well-dated cores spanning the entire middle to late Holocene record along macrotidal coasts. To investigate the sedimentary response of this macrotidal coast to decreasing rates of RSL rise, we acquired four cores up to 32 m in length and Chirp seismic profiles along the west coast of Korea. Core sediments were analyzed in terms of sedimentary texture, structure, and facies. Nineteen optically stimulated luminescence (OSL) and fourteen 14C accelerated mass spectrometry (AMS) ages constrain the timing of deposition of the sandy sediments. This relatively dense distribution of ages is used to determine how deposition rates changed through time. We also use a compilation of previously published RSL indices for the southwestern Korean coast in order to better constrain RSL changes through time. Results show that the evolution of the Gochang coastline switched from a tide-dominated environment to a wave-dominated environment during the latter stage of transgression as the rate of the sea-level rise decreased. Rugged antecedent topography likely led to the development of tidal currents and the formation of a tide-dominated tidal flat during rapid RSL rise from 10 to 6 ka. As the tidal channels filled with fine-grained sediments from 6 to 1 ka, tidal amplification likely waned leading to a greater role of wave energy in shaping the formation of the sandy open-coast tidal flat. Since 1 ka, wave-dominated environments formed sand-rich tidal beaches and flats. Decreasing changes in rates of the RSL rise resulted in changes in depositional environments from a tide-dominated intertidal flat to an open-coast tidal flat and finally a wave-dominated tidal beach. This study highlights the important role that rates of RSL rise play on not only sedimentation rates in a shelf setting but also playing a role in the switch from a tide-dominated to a wave-dominated setting.

Hunter-gatherers in labyrinth karst: An Early Holocene record from Gunung Sewu, Java

Gua Mandung is an inland prehistoric site in Gunung Sewu karst area of central Java, Indonesia. This area is rich in valleys and corridors which make up Gunung Sewu's distinct labyrinth-like landscape. For Java, Gunung Sewu is known to have a relatively harsh environment with limited access to permanent water sources and a short wet season. However, here we report evidence of occupation at the site of Gua Mandung since at least 11,073 cal BP. An abundance of terrestrial fauna remains alongside numerous bone tools with differing functionalities suggests that these early cave dwellers applied well-developed subsistence strategies to maximise the available resources. Gua Mandung records continuous exploitation of small to large terrestrial fauna including monkeys, porcupine, deer, pig, cattle, rat, snake, and monitor lizard. The site's proximity to nearby lakes and a ∼ 5 km walk to the coast also provided Gua Mandung's early inhabitants with secondary aquatic resources such as fish, freshwater shells, marine shells, barnacles, crab, and sea urchin. Based on our findings from the Gua Mandung excavation, and in comparison with surrounding archaeological sites, coastal resource exploitation appears to have been a common, albeit more minor, subsistence strategy employed by the early inland communities of the Gunung Sewu karst area.

Assigning causality to events in the Holocene record of coral reefs

Abstract The uncemented reef-frameworks of Pacific Panamá, which have been dominated throughout the Holocene by branching corals of the genus Pocillopora , experienced a hiatus in vertical accretion lasting c. 2300 years, beginning c. 4100 years ago. The hiatus has been attributed to an increase in variability of the El Niño–Southern Oscillation (ENSO). We tested the alternative hypothesis that the hiatus was solely the result of bioerosion, assuming an acute disturbance halted coral growth 1800 years ago (the time at which reef accretion resumed after the hiatus) and that the entire framework remained in the taphonomically active zone at that time. We calculate that it would have taken 167–511 years for bioerosion to fully remove 2300 years-worth of framework growth under those circumstances. In fact, most of the reef-framework in Panamá is stabilized in sediment that prevents the activity of bioeroders; only the upper c. 1 m of open framework – several decades-worth of growth at most – would have been vulnerable to erosion, greatly increasing the time required to bioerode 2300 years of accumulation. We conclude that the hiatus was not solely an artefact of bioerosion; rather, a long-term increase in ENSO variability suppressed coral growth and vertical reef accretion.

A Holocene Record of Vegetation Change and Mountain Pine Beetle Outbreaks at Lake of the Woods, Montana, USA

Los recientes brotes de escarabajos del pino de montaña (Dendroctonus ponderosae) se han caracterizado por no tener precedentes, en gran medida por la ausencia de información sobre su aparición antes de la documentación histórica. La capacidad de reconstruir brotes previos a los asentamientos, a partir de núcleos de sedimentos requiere la identificación y validación de indicadores apropiados. En este trabajo, proporcionamos un registro del cambio de la vegetación durante el Holoceno que indica posibles brotes del escarabajo del pino de montaña en un bosque de pino lodgepole (Pinus contorta) y de coníferas mixtas en Lake of the Woods, Montana. Utilizando un índice de diferencia de polen normalizado, identificamos positivamente brotes de escarabajos del pino de montaña posteriores al asentamiento, que sirvieron como puntos de calibración para identificar otros brotes a lo largo del Holoceno. El registro obtenido de Lake of the Woods indica que el cambio de la vegetación fue promovido principalmente por las precipitaciones y que los múltiples brotes de escarabajos del pino de montaña reconstruidos, contemporáneos y anteriores al asentamiento, se produjeron durante períodos en los que la composición del bosque estaba dominada principalmente por Pinus spp. La aparición de uno de estos brotes en ∼8200 cal yr BP es consistente con otros dos registros en las Rocosas del Norte, lo que sugiere un gran brote regional durante esta época.

Taphonomy of two Holocene penguin taphocoenoses in Potter Peninsula, South Shetland Islands, Antarctica

ABSTRACT Abandoned rookeries belonging to any of the Pygoscelis species are very particular taphocoenosis, usually preserved due to the accumulations of bones, pebbles, and guano year after year in the same nesting area, that condense together with other biogenic material and form ornithogenic sediments. The results of the excavation, sieved and analyses of sediment and materials found in two rookeries formed during the last 8000 years, named Pingfo I and Pingfo II and found in the 25 de Mayo/King George Island (South Shetland Islands, West Antarctica) are presented here. The analyses of the bones and eggshells, taxonomic and ontogenetic composition, elements representation, transport degree, predation, and scavenging marks, together with the micropalaeontological content provided informative tools for the reconstruction of the nesting areas, suggesting that bones were transported and accumulated in Pingfo I that would represent high energy beach, whereas a breeding colony was settled in Pingfo II. The preservation of hexactinellid spicules and several arthropod remains are particularly informative for the levels at Pingfo I. The preservation of a Culicidae (Diptera) wing could be the first middle Holocene record of the group in Antarctica, the only continent without extant mosquitoes.