Holocene Age Research Articles

Implications of (reworked) aeolian sediments and paleosols for Holocene environmental change in Western Mongolia

In the semi-arid to semi-humid regions of western Mongolia four different geomorphological aeolian and fluvial archives were investigated in order to gain environmental information of landscape evolution during the late glacial and the Holocene. These archives, which contain aeolian deposits, fluvial sediments, and paleosols, are situated upon glacial moraines, fluvial terraces, floodplains, or mountain slopes. While radiometric dating provides information about the age of the sediment and paleosols, grain size and element distribution provide information about the sediment source and soil development.Extensive aeolian sediment transport occurred from 17 to 10ka during the late glacial when climate was cold and dry. Since that period the developing steppe and alpine meadow vegetation served as a dust trap. During the warm and wet early to mid-Holocene sediment transport was reduced under a dense vegetation cover. All paleosols of the investigated archives show late Holocene ages which point to an environmental turning point around 3ka. Since then, the Neoglacial period started with cooler climate conditions and periglacial processes intensified again. Recognizable glacier advances occurred during the Little Ice Age several centuries ago. Since then, global climate change leads to warmer and more arid conditions. During the late Holocene, a new period of strong geomorphological activity started and huge quantities of aeolian, colluvial and fluvial sediment accumulated. These intensified soil relocation processes cannot be explained exclusively by climate change because there are no explicit indications found in the palynological and lacustrine records of Mongolia. This discrepancy suggests that the additional factor of human impact has to be considered, which amplified the climate signal on the landscape. Simultaneously, when the enhanced geomorphological processes occurred, the prehistoric people changed from hunting and gathering to livestock husbandry. A first extensive population growth of the Scythian nomadic tribes is documented for the beginning of the Bronze Age in Central Asia. This temporal concurrence supports the finding of a first extensive human impact on landscape development.

Of Meuse and Man: the geomorphogenetic and archaeological predictive maps of the Dutch Meuse valley

AbstractFor the first time, geomorphology and archaeology are combined for a 165 km long stretch of the Meuse river, resulting in a geomorphogenetic map (GKM) and a series of archaeological predictive maps (AVM). The maps cover the central part the Meuse valley, located in the province of Limburg between Mook in the north and Eijsden in the south. The area consists of fluvial and aeolian landforms of the Holocene Meuse floodplain and Younger Dryas aged terraces along it, spanning a period of approximately 15,000 years of landscape genesis and human habitation. The GKM more clearly discriminates between map units of Younger Dryas and early Holocene age than in previous mappings of the Meuse valley. The AVM series provide predictive information on the location of sites for four distinct consecutive archaeological periods and four main cultural themes. The maps contribute to a better understanding of landscape processes (fluvial and aeolian geomorphology and the impact of man on river behaviour), and the possibilities for human habitation and land use in prehistoric and historic times.

Relationship between geohydrology and Upper Pleistocene–Holocene evolution of the eastern region of the Province of Buenos Aires, Argentina

The Upper Pleistocene–Holocene geological evolution, which is characterized by its landscape-forming energy and is related to geological and geomorphological complexity, has an impact on the groundwater dynamics of coastal aquifers. The geological configuration of a sector of the east coast of the Province of Buenos Aires was analyzed, as well as its connection with the geological and geomorphological history of the region during the Late Pleistocene and Holocene, and its influence on the regional and local geohydrological behaviour. This analysis was based on the application of the concept of hydrofacies. Boreholes were drilled and sampled (with depths of up to 40 m), and vertical electrical sounding, electrical tomography and pumping tests were undertaken. The description of the cutting samples by means of a stereo microscope, the interpretation of satellite images, and the construction of lithological and hydrogeological profiles and flow charts were carried out in the laboratory, and then integrated in a GIS. The identification of the lithological units and their distribution in the area allowed the construction of an evolutionary geological model for the Late Pleistocene and Holocene. Three aquifer units can be recognized: one of Late Pleistocene age (hydrofacies E) and the other two of Holocene age (hydrofacies A and C); their hydraulic connection depends on the occurrence and thickness variation of the aquitard units (hydrofacies B and D). The approach adopted allows the examination of the possibilities for groundwater exploitation and constitutes an applied conceptual framework to be taken into consideration when developing conceptual and numerical models at the local and regional scales.

New constraints on Arctic Ocean Mn stratigraphy from radiocarbon dating on planktonic foraminifera

Variations in the abundance of manganese (Mn) in Arctic Ocean sediments are used as a tool to identify glacial and interglacial periods. This study aims to provide new insight into the applicability of Mn as a stratigraphic tool in the topmost sediment and to investigate the occurrence of Mn peaks in sediments within the range of radiocarbon dating. In combination with variations in ice-rafted debris (IRD), radiocarbon dating is used to better constrain the stratigraphic occurrence of Mn peaks, and the synchroneity between multiple records, especially during the late glacial and the Holocene. We find that a hiatus spanning MIS 2 is widely observed in most of our cores, resulting in a merging of Mn peaks of Holocene age and the later part of MIS 3. The Holocene Mn peak is usually high amplitude but short, while the MIS 3 Mn peak has a lower amplitude and is protracted. Where preserved, MIS 2 sediments form a 2–3 cm thick layer characterized by a light color, low Mn content, sparse IRD and low foraminiferal abundance. IRD variations provide a powerful tool to identify the boundary of the Holocene and late MIS 3 in cores with a MIS 2 hiatus. Because the IRD content displays a general increment from the start of MIS 3, and both the Holocene and MIS 2 show small IRD variations, the end of MIS 3 can be pinpointed to the point of decrease in IRD. The hiatus of MIS 2 is widely observed in our cores, suggesting extensive persistent sea ice coverage during the peak of the last glacial cycle, with sharply reduced sedimentation throughout the Arctic Ocean. Identifying similar events during previous glacial periods may be an important step towards constructing longer and more accurate chronologies for Arctic Ocean sediments.

Palaeoenvironmental interpretations based on molluscs from mid-Holocene lacustrine limestones, Mato Grosso do Sul, Brazil

In central Brazil there are continental carbonate rocks in three different geological contexts – the Pleistocene wackestones in the Corumba city (Xaraies Formation), the mid-Holocene limestones lenses in the Pantanal Plain (Pantanal do Miranda) and old and modern tufas in the Serra da Bodoquena (Serra da Bodoquena Formation). We present here a systematic and taphonomic study of the molluscs found in the carbonate deposits in the Serra da Bodoquena and the limestones lenses of the Pantanal do Miranda, which provide information concerning the carbonate palaeoenvironments of these two distinct areas. Seven molluscan species were found: the gastropods Marisa sp., Pomacea canaliculata, an unidentified hydrobiid, Idiopyrgus sp., Biomphalaria sp. and Megalobulimus sp., and the bivalve Pisidium sp. The gastropods include species still living in the area today, which supports a Holocene age for the limestones, as indicated by published 14C dates. Overall, the data obtained from the Serra da Bodoquena carbonates suggest a freshwater environment with minimal current-wave action, in an area probably fed by springs, close to a terrestrial environment, in view of the assemblage composed of Pomacea canaliculata, the unidentified hydrobiid, Idiopyrgus sp., Biomphalaria sp. and Megalobulimus sp. The lacustrine palaeoenvironment in the Pantanal do Miranda area was different, as indicated by the presence of Marisa sp. and absence of shallow-water species such as Biomphalaria sp. The gastropods from Serra da Bodoquena and Pantanal do Miranda are predominantly aquatic and amphibious; they are probably younger than the terrestrial gastropods reported from fine-grained limestones in the Corumba area.

Making archaeological sense of Kennewick Man

Four published inferences about Kennewick Man that can distort an understanding of Pacific Northwest prehistory fail a review of new and pre-existing evidence. These are: he was a seal hunter from the northern Northwest Coast; the spear in his pelvis represents a Western Stemmed Tradition type; he was buried in an extended position; and he is more closely related genetically to people of the northern Columbia Plateau than any other Native Americans. A review of damage to the skeleton and its position at discovery indicates semi-flexed burial with downstream orientation. The projectile point in his pelvis matches an Old Cordilleran Tradition type not known from the region where he was found. Stable C and N isotope comparisons to a faunal collection of comparable early Holocene age, and with a contemporary individual found near the Kennewick locality demonstrate that he had a normal diet for early Holocene interior Washington. The high δ15N that stimulated the seal-hunter idea might instead result from nutritionally inadequate subsistence practices. Claims of genetic relationships to a specific Native American tribe suffer from bias and the near absence of comparative data from the U.S. Kennewick Man died at a time of ethnic replacement in the Columbia Plateau and these findings support three possible solutions to his identity that might never be resolved.

Chapter 11 The Archipelago Group: current understanding

Abstract The geology and stratigraphy of the Archipelago Group are reviewed and new data presented to improve understanding. Major lithofacies are bioclastic limestones, bioturbated mottled marlstones, micritic limestones, trace fossil-bearing mudstones, quartzose sandstones and reworked volcanic material of Mio-Pliocene and Pleistocene age. The succession overlies the Pre-Neogene submarine fan turbidites and tectonic mélanges of ophiolite derivation and Mithakhari rocks, and is overlain by Quaternary deposits of late Pleistocene–Holocene age. The Neogene sequences were deposited in wave- and current-agitated shallow-marine intertidal and relatively deeper-water subtidal, nearshore and offshore shelfal environments. The existing stratigraphic framework is examined and suggestions made for improvement.

Shear wave velocity as function of cone penetration resistance and grain size for Holocene-age uncemented soils: a new perspective

For feasibility studies and preliminary design estimates, field measurements of shear wave velocity, V s, may not be economically adequate and empirical correlations between V s and more available penetration measurements such as cone penetration test, CPT, data turn out to be potentially valuable at least for initial evaluation of the small-strain stiffness of soils. These types of correlations between geophysical (Vs) and geotechnical (N-SPT, q c-CPT) measurements are also of utmost importance where a great precision in the calculation of the deposit response is required such as in liquefaction evaluation or earthquake ground response analyses. In this study, the stress-normalized shear wave velocity V s1 (in m/s) is defined as statistical functions of the normalized dimensionless resistance, Q tn-CPT, and the mean effective diameter, D 50 (in mm), using a data set of different uncemented soils of Holocene age accumulated at various sites in North America, Europe, and Asia. The V s1–Q tn data exhibit different trends with respect to grain sizes. For soils with mean grain size (D 50) < 0.2 mm, the V s1/Q tn 0.25 ratio undergoes a significant reduction with the increase in D 50 of the soil. This trend is completely reversed with further increase in D 50 (D 50 > 0.2 mm). These results corroborate earlier results that stressed the use of different CPT-based correlations with different soil types, and those emphasized the need to impose particle-size limits on the validity of the majority of available correlations.

Distinguishing Depositional Setting For Sandy Deposits In Coastal Landscapes Using Grain Shape

Abstract: Several methods exist that use sediment properties to characterize depositional setting and related mechanisms of transport, including analysis of grain-size distributions, sediment petrology, micromorphology, and grain structure. Techniques that rely on electron or optical microscopy produce results with varying degrees of success and applicability. Here, a new method is presented and used to differentiate between littoral and eolian sands that were extracted from recently formed landforms, as well as landforms that are from mid to late Holocene in age. The method utilizes a standard optical microscope with a mounted digital camera, paired with freely available software (ImageJ) to characterize grain shape parameters. The method was tested on nearly 6000 sand grains from samples with varied transport histories, and it was found that grain solidity was the most distinguishable characteristic between eolian and littoral samples, differentiating them 86% of the time for calibration samples. The method was used to correctly identify the mechanism of transport for 76% of the samples. Patterns in the results indicated that this method could be extended to link potential sediment sources to various depositional basins, and future work includes testing the method in areas with a different mineralogy and/or landscape history.

CALDERA KSUDACH (KAMCHATKA): MODERN PROCESSES OF RELIEF FORMING AND MAIN FEATURES OF THE VALLEY NETWORK STRUCTURE

Ksudach volcano (Kamchatka) consists of 5 completely or partially nested calderas Late Pleistocene (calderas I and II) and Holocene (III–V) age. Analysis of the processes of relief forming and structure of intracaldera river valleys leads to the conclusion that, despite the high Holocene volcanic activity of Ksudach (volcano-tectonic collapse, significant amounts of ejected pyroclastic material) the upper reaches of many of modern valleys were formed on the slopes of calderas I and II. And nowadays they are still function as the upper parts of the younger Holocene valleys of calderas IV and V. These fragments of upper parts of the Late Pleistocene river network surviving after Holocene caldera forming explosions continued to concentrate runoff and as a result the lower parts of the river network, destroyed during eruptions, begun to restore, but depending on the newly formed volcanic relief. The growth of the Shtyubel cone within the caldera V also had a significant influence on the orientation and morphology of adjacent valleys: in particular, it has led to Lagernyi creek alteration, which made a turn for 120° during the Late Holocene. The fragment of its ancient valley preserved in the form of a flat-bottomed saddle on the WSW of the vlc. Shtyubel and now it’s gradually degraded by erosion. Explosive activity of Ksudach vlc. (including Shtyubel cone) had great influence on the intracaldera river systems: powerful pyroclastic flows repeatedly filled up their valleys and came down along the river Teplaya. Subsequent incision of valleys led to the formation in them of erosion terraces composed by pyroclastic deposits.

Late Pleistocene to Holocene evolution of the Emba Delta, Kazakhstan, and coastline of the north-eastern Caspian Sea: Sediment, ostracods, pollen and dinoflagellate cyst records

Six cores, each approximately 10m long, of late Pleistocene to Holocene age were studied from the Emba Delta region in the north-eastern Caspian Sea. Radiocarbon dates provide ages within the range of 47,820 to 12,020calBP for the middle sections, and for post-1950 close to surface. The ages fall within Marine Isotope Stage (MIS) 3, MIS 2 and MIS 1 (with MIS 4 also inferred). Four lithological units are present, each separated by an erosional contact. Unit 4 is equated with MIS 4 and consists of over-consolidated, east-west trending aeolian sands deposited during the late Pleistocene Atelian lowstand. Unit 3 is equated with MIS 3 and is a low-energy, shallow open water or lagoonal deposit based on ostracod faunas. Pollen from mesophilic trees is common, confirming warm climatic conditions. Floristic elements such as Engelhardia and Carya were shared with East Asia. Frequent Taxodiaceae pollen occurs, derived from Glyptostrobus pensilis, a seasonal freshwater swamp tree, now found naturally only in isolated relict stands in East Asia. This suggests that the north-eastern Caspian region was a ‘refugium’ supporting Glyptostrobus swamp vegetation during MIS 3. There is no evidence to indicate that these are reworked occurrences. Unit 2 consists of early Khvalynian transgressive barrier sands and Unit 1 of shoreface sands and muds of Holocene age. The late Khvalynian highstand and the Last Glacial Maximum (LGM) record are eroded by the Mangyshlak unconformity after ca. 12,500calBP. The Holocene interval contains frequent foraminifera and dinoflagellate cysts (dinocysts) of restricted ‘marine’ affinity (e.g. Lingulodinium machaerophorum). The dinocysts Pterocysta cruciformis and Impagidinium inaequalis are found commonly in the Caspian Sea for the first time. Results are compared with palynological and ostracod assemblages in surface samples from the eastern Caspian Sea coastal region.

Overlapping paleoichnology, paleoecology and taphonomy: Analysis of tooth traces in a Late Pleistocene-early Holocene megafaunal assemblage of Brazil and description of a new ichnotaxon in hard substrate

Tooth traces are key evidence in vertebrate taphonomy, paleoecology and paleoichnology. They are product of feeding behavior of vertebrates and can also be evaluated in biostratinomic perspective. Regarding the Quaternary fossil record of vertebrates in Brazil, the taphonomic-paleoecological information of tooth traces has been underexplored. Recently, features of this sort were identified in Quaternary mammals fossils recovered from Lajedo da Escada caves, state of Rio Grande do Norte, northeastern Brazil, consisting in an opportunity to unveil taphonomic, paleoichnological and paleoecological aspects of the Quaternary megafauna. The ichnospecies Machichnus bohemicus and M. fatimae are recorded in the Late Pleistocene-early Holocene age. The latter is a new ichnospecies of Machichnus described herein. The traces M. fatimae and M. bohemicus observed in Glyptotherium sp. were generated outside the cave by an adult individual of the large-sized canid Protocyon troglodytes during event of predation. Nonetheless, M. bohemicus recognized in Eremotherium laurillardi and Smilodon populator was generated by either a juvenile individual of P. troglodytes or an adult of the small-sized canid Cerdocyon thous, in a scavenging context, outside the cave. Probably, other tooth traces previously reported to the Quaternary of Brazil (in the states of Ceará and Minas Gerais) can be assigned to Machichnus.

Isotope composition of a lithalsa in the Sentsa River valley (East Sayan Mountains)

The ice-rich core formation within the core of the lithalsa in the Sentsa River valley (West Buryatia) was studied. The concentrations of stable oxygen and hydrogen isotopes in the ice were determined, the plant residues in the enclosing deposits were aged. It was found that the lacustrine loams enclosing the ice body were accumulated about 4700–7000 years ago. The ice core of the lithalsa was characterized by δD values from 141.9 to–159.8‰, δ18O from–19.52 to–21‰, and dexc within 4.1–17.29‰. Small variations in the isotope composition of the ice–soil material within the lithalsa core point to its formation in an open system with water inflow from outside. The values of δ18O and δD were much closer to those for recent middle-winter and late-autumn atmospheric precipitation, as well as for riverine water, which pointed to a Holocene age of the ice.

The impact of solar radiation and solar activity on climate variability after the end of the last glaciation

This paper analyzes climate changes since the end of the last glaciations 19–20 thousand years ago, including the modern warm interglacial Holocene age, which started about 11.5 thousand years ago. The connection between the impact of the orbital effect and solar activity on the Earth’s climate is studied. This is important for estimation of the duration of the modern interglacial period. It is shown that there is significant inconsistency between temperature variations in Holocene, which is deduced from the large amount of recently obtained indirect data and the temperatures reproduced in the climate models. The trends of climate cooling in the Holocene on the whole and during the last 2000 years are investigated.

Soil genesis and mineralogy across a volcanic lithosequence

Lithology is a principle state factor of soil formation, interacting with climate, organisms, topography and time to define pedogenesis. A lithosequence of extrusive igneous lithologies (rhyolite obsidian, dacite, andesite and basalt) was identified in the Clear Lake Volcanic Field in the Coast Range of northern California to determine the effects of lithology on pedogenesis, clay mineralogy and soil physiochemical properties. Based on regional landscape erosion rates (0.2–0.5mmyr−1), the soil residence times for the investigated pedons (~150cm deep) were of the order of 3000 to 7500years indicating that the soils developed under the relatively stable Holocene mesic/xeric climate regime. Soils from all lithologies developed to a similar Xeralf taxonomy with remarkably consistent physiochemical properties. Although total (Fet) and dithionite-citrate extractable (Fed) iron concentrations diverged across lithologies, the degree of weathering as assessed by the Fed/Fet ratio was similar across the lithosequence. In spite of large differences in silica content of the parent materials, the clay mineralogical assemblage of all lithologies was dominated by kaolin minerals (kaolinite and/or halloysite). All pedons displayed an increase in halloysite and the degree of halloysite hydration with increasing depth, except the basalt pedon, which was dominated by kaolinite with only trace halloysite. We attribute this lack of halloysite in the basalt pedon to the lower silica activities associated with this silica-poor lithology. There was a lack of nanocrystalline minerals across all lithologies as inferred from selective dissolution. The dominance of crystalline materials is a function of the xeric soil moisture regime whereby summer soil profile desiccation promotes dehydration and crystallization of metastable nanocrystalline precursors. Further, the pronounced summer dry period results in dehydration of halloysite (1.0nm) to halloysite (0.7nm; also referred to as meta halloysite in some literature), together with transformation to kaolinite, in the upper soil profile. In spite of the relatively young soil residence times of these soils (Holocene age), the effects of lithology persisted only in differences in Fe oxide concentrations (Fed), as well as a lack of significant halloysite in basalt pedons. The overwhelming effect of climate in these highly weatherable parent materials narrowed the trajectory of pedogenesis, resulting in soils from contrasting lithologies converging on kaolin mineralogy, a lack of nanocrystalline constituents, and similar soil physiochemical properties.

Microbial lipid signatures and substrate potential of organic matter in permafrost deposits: Implications for future greenhouse gas production

AbstractA terrestrial permafrost core from Buor Khaya in northern Siberia comprising deposits of Late Pleistocene to Early Holocene age has been investigated to characterize living and past microbial communities with respect to modern and paleoclimate environmental conditions and to evaluate the potential of the organic matter (OM) for greenhouse gas generation. Microbial life markers—intact phospholipids and phospholipid fatty acids—are found throughout the entire core and indicate the presence of living microorganisms also in older permafrost deposits. Biomarkers for past microbial communities (branched and isoprenoid glycerol dialkyl glycerol tetraether as well as archaeol) reveal links between increased past microbial activity and intervals of high OM accumulation accompanied by increased OM quality presumably caused by local periods of moister and warmer environmental conditions. Concentrations of acetate as an excellent substrate for methanogenesis are used to assess the OM quality with respect to microbial degradability for greenhouse gas production. For this purpose two acetate pools are determined: the pore water acetate and OM bound acetate. Both depth profiles reveal similarities to the OM content and quality indicating a link between the amount of the stored OM and the potential to provide substrates for microbial greenhouse gas production. The data suggest that OM stored in the permafrost deposits is not much different in terms of OM quality than the fresh surface organic material. Considering the expected increase of permafrost thaw due to climate warming, this implies a potentially strong impact on greenhouse gas generation from permafrost areas in future with positive feedback on climate variation.

Holocene multistage massive ice, Sabettayakha river mouth, Yamal Peninsula, northwest Siberia

Massive ground ice of Holocene age occurs in multiple boreholes near the Sabettayakha River mouth, on the coast of the Gulf of Ob (Ob Bay), Yamal Peninsula, northwest Siberia. The multistage massive-ice bodies are up to 5.7m thick and occur in Holocene sediments of modern floodplain and the first terrace of the coastal lagoon. Massive-ice bodies and cryopegs occur at three to four depths. According to stable isotope analyses, the multistage massive ice bodies formed syngenetically during the freezing of water-saturated sediment, under intensive cryogenic fractionation. Very negative values of δ2H (up to –199.7 ‰) and δ18O (up to –26.48 ‰) for the massive ice are unique not only for Holocene ground ice of Yamal Peninsula, but also for Late Pleistocene ice of northwest Siberia. The ratio of the chloride and sulfate anions, pollen spectra and presence of algae in three different types of massive ice near the Sabettayakha River mouth suggest that (1) vertically layered brown ice formed during freezing of water-saturated sands of the Ob Gulf; (2) brown non-laminated ice formed as a result of freezing of sublake talik water; and (3) white ultra-fresh ice also formed from lake and river water.

Early Holocene age and provenance of a mid-shelf delta lobe south of the Strait of Bosphorus, Turkey, and its link to vigorous Black Sea outflow

The chronology of an abandoned Holocene delta lobe (present water depth ~40–70m) on the northeastern shelf of the Marmara Sea south of the Strait of Bosphorus was revised from the early Holocene (~11.0–9.7calka) to the middle Holocene (6.65–3.75calka) by Eriş et al. (Eriş, K.K., Ryan, W.B.F., Çağatay, M.N., Sancar, Ü., Lericolais, G., Ménot, G., Bard, E., 2007. The timing and evolution of the post-glacial transgression across the Sea of Marmara shelf south of İstanbul. Marine Geology, 243, 57–76). Three independent seismic and multibeam surveys and replotting of navigational fixes for the 1992/1993-vintage survey lines which Eriş et al. correlated to their MD04-2750 giant piston core confirm that they misplotted the location of the MD04-2750 core site on seismic profiles by a minimum of ~200m. Because of rapid convergence of seismic reflections in this critical area, the assessment of the age of the Holocene delta proposed by Eriş et al. is incorrect. Instead, existing and new data allow the age of this delta lobe to be refined to ~11.1–10.2calka (±~200–300years each) using several dated cores and the MD04-2750 chronology itself. A dense grid of previously unpublished seismic data shows that the lobe emanates from the Strait of Bosphorus and not from any of the local small streams. Mineralogy of the very fine sand fraction of the delta excludes the Kurbağalıdere stream as a source of the detritus, as does the composition of detrital hornblendes. It is concluded that the early Holocene delta lobe indeed records a period of strong Black Sea outflow, as advocated by co-authors RNH and AEA in 2002. Re-examination of multibeam imagery from the strait itself provides support for strong southward flow that potentially coincided with accumulation of the delta lobe at the southern exit of the strait.

Latest Pleistocene and Holocene glacial events in the Colonia valley, Northern Patagonia Icefield, southern Chile

ABSTRACTThe Northern Patagonia Icefield (NPI) is the primary glaciated terrain worldwide at its latitude (46.5–47.5°S), and constraining its glacial history provides unique information for reconstructing Southern Hemisphere paleoclimate. The Colonia Glacier is the largest outlet glacier draining the eastern NPI. Ages were determined using dendrochronology, lichenometry, radiocarbon, cosmogenic 10Be and optically stimulated luminescence. Dated moraines in the Colonia valley defined advances at 13.2 ± 0.95, 11.0 ± 0.47 and 4.96 ± 0.21 ka, with the last being the first constraint on the onset of Neoglaciation for the eastern NPI from a directly dated landform. Dating in the tributary Cachet valley, which contains an ice‐dammed lake during periods of Colonia Glacier expansion, defined an advance at ca. 2.95 ± 0.21 ka, periods of advancement at 810 ± 49 cal a BP and 245 ± 13 cal a BP, and retreat during the intervening periods. Recent Colonia Glacier thinning, which began in the late 1800s, opened a lower‐elevation outlet channel for Lago Cachet Dos in ca. 1960. Our data provide the most comprehensive set of Latest Pleistocene and Holocene ages for a single NPI outlet glacier and expand previously developed NPI glacial chronologies.

An early Holocene age for the Vatn landslide (Skagafjörður, central northern Iceland): Insights into the role of postglacial landsliding on slope development

Recent research in northern Iceland has highlighted a significant period of rock slope instability during the early Holocene due to the combined effects of postglacial rebound, relative sea-level fall, and glacially oversteepened mountain slopes. Using the Vatn landslide (Skagafjörður, central northern Iceland) as an example, this paper focuses on this period and describes the sequence of events that led to landsliding. Geomorphic mapping, stratigraphical evidence, and both radiocarbon and tephra dating were applied. Collectively, the data acquired indicate that the landslide occurred between 11,400 and 10,790 cal. yr BP. However, while rock slope failure represents a significant disintegration of mountain slopes, this study suggests that large postglacial landslides might also play a role in arresting sediment transport from other hillslope processes rather than contributing large volumes of sediment.