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We present new lithostratigraphic, pollen‐stratigraphic and tephrochronological data obtained from a sediment sequence in a small lake basin in Glen Builg, eastern Cairngorms, with mapping of the surrounding glacial geomorphological features. The collective evidence indicates that basin organic sediment accumulation started during the Windermere Interstadial at ~14.3 ka. The new results reaffirm the conclusions of Clapperton et al. (1975), that any occupation of the eastern Cairngorms by Loch Lomond ('Younger Dryas') Stadial glacier ice was spatially restricted. The record also suggests that harsh climatic conditions prevailed throughout the Windermere Interstadial, probably due to the relatively high altitude of the site (~460 m) and its proximity to major Cairngorm peaks. Our new, more comprehensive study provides a robust chronology, and reveals several palaeoenvironmental signals congruent with other recently reported Scottish Highlands records. Key similarities with regional records are: (i) a short climatic reversal corresponding to GI‐1d in the Greenland stratotype sequence; (ii) a two‐phased Loch Lomond Stadial, with a transition around the Vedde Ash, dating to ~12.1 ka; and (iii) a delayed response to Early Holocene climatic warming of ~250 years, before soils were sufficiently stabilised to permit shrub vegetation establishment. [ABSTRACT FROM AUTHOR]

Because global sea level during the last interglacial (LIG; 130–115 ka) was higher than today, the LIG is a useful approximate analogue for improving predictions of future sea-level rise. Here, we synthesize sea-level proxies for the LIG in the glaciated Northern Hemisphere for inclusion in the World Atlas of Last Interglacial Shorelines (WALIS) database. We describe 82 sites from Russia, northern Europe, Greenland and North America from a variety of settings, including boreholes, riverbank exposures and along coastal cliffs. Marine sediments at these sites were constrained to the LIG using a variety of radiometric methods (radiocarbon, uranium–thorium, potassium–argon), non-radiometric methods (amino acid dating, luminescence methods, electron spin resonance, tephrochronology) as well as various stratigraphic and palaeo-environmental approaches. In general, the sites reported in this paper do not offer constraint on the global LIG highstand, but rather evidence of glacial isostatic adjustment (GIA)-influenced sea-level positions following the Marine Isotope Stage 6 glaciation (MIS 6; 191–130 ka). Most of the proxies suggest that sea level was much higher during the LIG than at the present time. Moreover, many of the sites show evidence of regression due to sea-level fall (owing to glacial isostatic uplift), and some also show fluctuations that may reflect regrowth of continental ice or increased influence of the global sea-level signal. In addition to documenting LIG sea-level sites in a large swath of the Northern Hemisphere, this compilation is highly relevant for reconstructing the size of MIS 6 ice sheets through GIA modelling. The database is available at https://doi.org/10.5281/zenodo.5602212 (Dalton et al., 2021). [ABSTRACT FROM AUTHOR]

Volcanic ash (fine-grained tephra) within Greenland ice cores can complement the understanding of past volcanism and its environmental and societal impacts. The presence of ash in sparse concentrations in the ice raises questions about whether such material represents primary ashfall in Greenland or resuspended (remobilized) material from continental areas. In this article, we investigate this issue by examining tephra content in quasi-annual samples from two Greenland ice cores during a period of ca. 20 years and considering their relationships with sulphur and particulate data from the same cores. We focus on the interval 815–835 CE as it encompasses a phase (818–822 CE) of heightened volcanogenic sulphur previously ascribed to an eruption of Katla, Iceland. We find that tephra is a frequent but not continuous feature within the ice, unlike similarly sized particulate matter. A solitary ash shard whose major element geochemistry is consistent with Katla corroborates the attribution of the 822±1 CE sulphur peak to this source, clearly showing that a single shard can signify primary ashfall. Other tephras are present in similarly low abundances, but their geochemistries are less certainly attributable to specific sources. Although these tephra shards tend to coincide with elevated sulphur and fine (<10 μm) particulates, they are not associated with increased coarse (>10 μm) particle concentrations that might be expected if the shards had been transported by dust storms. We conclude that the sparse shards derive from primary ashfall, and we argue that low tephra concentrations should not be dismissed as insignificant [ABSTRACT FROM AUTHOR]

It has long been assumed that the last glacier expansion in the Scottish Highlands, the Loch Lomond Readvance (LLR), resulted from a cold reversal that was broadly coeval with the 'Younger Dryas' episode. This view has recently been challenged, with the suggestion that glacier ice had disappeared from Rannoch Moor, one of the main ice accumulation centres in the SW Scottish Highlands, by as early as 12.5 ka, i.e. within the first half of the 'Younger Dryas'. Here we present new radiocarbon, tephrostratigraphical and pollen-stratigraphical evidence from one of the key sites on Rannoch Moor, the results of an experiment designed to test this hypothesis. Our results not only contradict that concept, but are fully compatible with other evidence from the SW Scottish Highlands that suggests that the LLR glaciers in this area continued to expand until towards the end of the 'Younger Dryas' period, and may have persisted in some places after the onset of the Holocene. We consider the possible reasons for this marked divergence in chronology, a matter that is crucial to resolve because the precise timing of the demise of the LLR glaciers has important palaeoclimatic and other implications. In the wider context, we also draw attention to problems with the general use of the term 'Younger Dryas' and why we regard the Greenland stratotype unit and term 'Greenland Stadial 1' (GS-1) a more secure stratigraphic comparator. • This paper is about one of the last major icefields to occupy the Scottish Highlands. • Our new data suggest this icefield was an extensive ice body until ∼11,500 years ago. • These results run counter to recent publications advocating much earlier ice decay. • The results have important palaeoclimatic and age-calibration implications. • This study also exemplifies problems with the general use of the term 'Younger Dryas'. [ABSTRACT FROM AUTHOR]

The establishment of a tephra framework for the Greenland ice-cores spanning the last glacial period, particularly between 25 and 45 ka b2k, provides strong potential for precisely correlating other palaeoclimatic records to these key archives. Tephra-based synchronisation allows the relative timing of past climatic changes recorded within different depositional environments and potential causal mechanisms to be assessed. Recent studies of North Atlantic marine records have demonstrated the potential of tracing cryptotephra horizons in these sequences and the development of protocols now allows a careful assessment of the isochronous nature of such horizons. Here we report on tephrochronological investigations of a marine sequence retrieved from the Goban Spur, Eastern North Atlantic, covering ∼25–60 ka b2k. Density and magnetic separation techniques and an assessment of potential transport and depositional mechanisms have identified three previously unknown isochronous tephra horizons along with deposits of the widespread North Atlantic Ash Zone II and Faroe Marine Ash Zone III. Correlations between the new horizons and the Greenland ice-core tephra framework are explored and despite no tie-lines being identified the key roles that high-resolution climatostratigraphy and shard-specific trace element analysis can play within the assessment of correlations is demonstrated. The previously unknown horizons are new additions to the overall North Atlantic tephra framework for the last glacial period and could be key horizons for future correlations. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, increased awareness of the considerable potential offered by tephrochronology in palaeoclimatic studies has fuelled a renewed interest in the tephra record preserved within the Greenland ice-cores. This renewal has occurred in tandem with the development of continuous flow analysis techniques, which provide high-resolution volcanic aerosol records. These chemical records are of considerable value for identifying tephra horizons composed of glass shards and also provide the basis for a new high-precision ice-core timescale, thus allowing ages to be assigned to volcanic events. Tephra horizons of glass shards in the ice-cores play a critical role for (1) testing and building chronological frameworks for the ice-cores and other sequences, (2) synchronising disparate palaeoclimatic sequences and testing phase relationships, (3) atmospheric pathway reconstruction, and (4) verifying the source of volcanic aerosol peaks. Here we review the results of over 25years of research into tephra horizons in the GRIP, GISP2 and NGRIP cores. We provide high-precision ages for horizons based on recently developed timescales and draw together geochemical characterisations of the products of 45 volcanic events deposited on the Greenland ice sheet and identified in the cores. There is a clear disparity between the number of volcanic aerosol peaks and the number of tephra horizons of glass shards identified thus far. However, this synthesis highlights the critical role of the Greenland ice-cores, firstly in the reconstruction of the history of Icelandic volcanic eruptions, and secondly the considerable value of some tephra horizons in facilitating the correlation of these key climatic archives to North Atlantic marine sequences. Other noteworthy issues include the potential of these cores to preserve tephra horizons from more distal volcanic sources such as North America, to resolve the debate surrounding the Thera eruption, and the observation that some tephra horizons are preserved within the ice without coeval volcanic aerosol signals. [Copyright &y& Elsevier]

Abstract: Sulphate records from Greenland ice-cores indicate that Marine Isotope Stages 4 and 5 were characterised by a higher incidence of large volcanic eruptions than other periods during the last glacial period, however, few investigations have focused on tephra deposits associated with these volcanic eruptions and the nature and origin of the events. Here we present a detailed tephrochronological framework of the products of 15 volcanic events spanning this interval; the majority of which have been preserved as cryptotephra horizons within the Greenland records. The major element compositions of individual glass shards within these horizons indicate that 13 of the eruptions originated from Iceland and 6 of these events can be correlated to the specific volcanic systems of Katla, Grímsvötn, Grímsvötn-Kverkfjöll and either Reykjanes or Veidivötn-Bárdarbunga. For the remaining Icelandic horizons a source from either the rift zone or a flank zone can be suggested based on rock suite affinities. Two horizons have been correlated to a source from the Jan Mayen volcanic system which represents the first discovery of material from this system within any Greenland ice-cores. The robust geochemical characterisations, independent ages for these horizons (derived from the GICC05 ice-core chronology) and stratigraphic positions relative to the Dansgaard-Oeschger climate events recorded in the Greenland ice-cores represent a critical framework that provides new information on the frequency and nature of volcanic events occurring in the North Atlantic region during MIS 4 and 5. This framework can now be utilised in the assessment of the differential timing and rate of response to the millennial-scale climatic events that characterised this period, through the use of the tephra horizons as time-synchronous tie-lines to other palaeoclimatic sequences. [Copyright &y& Elsevier]

Abstract: Well-resolved event-based stratigraphies in marine sediments spanning a significant portion of the last glacial period (60–8 kyr) provide a unique opportunity for time–stratigraphic correlation in the North Atlantic region. Here, we review the current methods available to chronologically constrain these event-based stratigraphies, highlighting, in particular, the value of tephrochronology as an independent tool to validate correlations between records. While the INTIMATE protocols (; Blockley et al., 2011) are equally applicable to marine and terrestrial records, spatially and temporally variable marine radiocarbon reservoir age effects (MREs) provide a challenge to using marine radiocarbon in the former as an independent chronostratigraphic tool. Despite the inherent uncertainties associated with ‘tuning’, we conclude that the mid-points of the common abrupt warming transitions associated with the well-defined, millennial-scale climate oscillations (the Dansgaard–Oeschger (D/O) cycles) observed in the oxygen isotopes of the Greenland ice cores and North Atlantic sea surface temperature (SST) records currently provide the most robust correlation tie-points from which to derive age control. In this invited INTIMATE special issue article we propose a new protocol for establishing marine event-based chronostratigraphies in the North Atlantic region and focus on areas of chronological potential in palaeoceanographic research. [Copyright &y& Elsevier]

Abstract: The Vedde Ash is the most important volcanic event marker layer for the correlation of Late Quaternary palaeoenvironmental archives in Europe and the North Atlantic. First defined from its type site localities near Ålesund, Western Norway, the Vedde Ash has now been traced across much of northern and central Europe, into northwest Russia, within North Atlantic marine sediments and into the Greenland ice cores. The Vedde Ash is thought to derive from an eruption of the Katla volcano in Iceland that occurred midway through the Younger Dryas/Greenland Stadial 1 (GS-1), ∼12.1ka BP. Visible and cryptotephra deposits of the Vedde Ash have been found in numerous stratified sites with robust chronologies, which allow its age to be constrained and its dispersal to be mapped. The eruption must have been highly explosive, however few proximal outcrops have been confirmed and this crucial ash layer remains almost exclusively distally-described and characterised using major element glass compositions. The widespread distribution, stratigraphic associations and consistent major element glass chemistry have led the Quaternary tephrochronological community to see the Vedde Ash as a robust and unique chronological marker layer for the Last Glacial to Interglacial Transition (∼10–18ka BP). Here we present new glass analyses of the Vedde Ash from multiple sites around the dispersal area, using a full suite of compositional analysis, including for the first time, single-grain trace element data. These data demonstrate the strong compositional coherence of Vedde Ash deposits. However, comparison with major, minor, and trace element compositional data from several other distally-described Icelandic tephras reveals that both before and after the Younger Dryas chronozone, there were eruptions that generated widespread tephra layers that have comparable glass shard compositions to the Vedde Ash. This implies that these numerous events not only hail from the same volcanic system, but that the melts share similar crystallisation trends and mixing patterns prior to eruption. It seems therefore that composition alone is insufficient for the correlation of some widespread tephra layers: good stratigraphic information and/or robust dating control are also essential. [Copyright &y& Elsevier]

Abstract: Five basaltic tephra horizons have been identified in the NGRIP ice-core during the last glacial period. Geochemical analyses indicate that these tephras are of Icelandic origin with one horizon identified as the Faroe Marine Ash Zone III (FMAZ III) — an important marker horizon in several marine records within the Faroe Islands margin. The FMAZ III is a few millimetres thick and is constrained to 38,122±723yr b2k (before year AD 2000) according to the Greenland Ice Core Chronology (GICC05). This event falls directly at the thermal peak of Greenland Interstadial 8 (GI-8) and a marine-ice correlation, based on the position of this tephra, suggests a close coupling of the marine and atmospheric systems at this time. The remaining tephras originate from the Eastern Volcanic Zone with the Katla volcanic system pinpointed as the dominant source. These are thought to represent previously unknown volcanic events which add considerably to our knowledge of Icelandic volcanism during this period. Independent ages are assigned to these events and together with major element characterisation, form the backbone of the tephrochronology framework presented here. Despite the identification of these tephras, this study also demonstrates that the sulphate record may not always act as a suitable proxy for the identification of tephra horizons in ice-core records. [Copyright &y& Elsevier]

The rhyolitic Upper Nisyros Pumice (UNP) from the Kos-Yali-Nisyros volcanic system has been detected as a cryptotephra layer in lacustrine sediments from the Sea of Marmara (SoM). A new independent age of the UNP eruption at 57.1 ± 1.5 cal ka BP has been interpolated using a combination of radiocarbon dating, tephrochronology and wiggle-matching of the SoM proxy record (Ca-curves) with Greenland oxygen isotope data, therewith confirming recently published radioisotopic dates of UNP land deposits. The UNP tephra in the SoM was identified by comparisons of the SoM tephra glass chemical dataset with published data of other marine tephra records from the Aegean Sea and the Megali Limni lacustrine sediment sequence (Lesvos Island). The stratigraphic position of the UNP tephra in these records verified its deposition in the SoM at the onset of MIS-3 and specifically at the termination of Greenland Interstadial GI-16. The new findings define the UNP tephra as a valuable time marker for the synchronisation of palaeoenvironmental data for this time period and help spurring the establishment of a robust tephrostratigraphical framework for the last ∼70 kyr in the Aegean-Black Sea region. • Upper Nisyros Pumices (UNP) detected as cryptotephra layer in Sea of Marmara sediments. • Sediment chronologies provide a revised age of the UNP eruption at 57.1 ± 1.5 ka BP. • UNP represent a valuable isochrone in Aegean-Black Sea region at the onset of MIS-3 and the termination of GI-16. [ABSTRACT FROM AUTHOR]

Estimating the environmental and societal impact of recent volcanic eruptions is a task aided by direct measurements and historical sources. Beyond the reach of first-hand accounts, our understanding of pre-historic volcanism is often hindered by dating uncertainties inherent to geological archives. Here, we minimize dating errors by analyzing the annually laminated sequences of two Central European lakes, Poggensee and Woseriner See. We focus on environmental transformations that occurred in the decades preceding and following the deposition of the Icelandic Saksunarvatn tephra, dated between ca. 10,300 and 10,200 cal. BP. As a first result, we provide two new independent age determinations for the ash layer detected in both sequences. Our estimates (10,264 ± 24 cal. BP at Poggensee and 10,282 ± 45 cal. BP at Woseriner See) place the age of this tephra deposit closer to Greenland estimates than to continental ones, possibly reducing the chronological gap between the multiple fallout events that characterize the Saksunarvatn Ash. A high resolution palaeoenvironmental characterization was carried out via pollen, thin sections and geochemical analysis. Both sequences show traces of a contemporaneous disturbance event dated to ca. 18 years before tephra deposition. In addition, environmental impact compatible with a cooling event is discernible for ca. 15 years following tephra deposition. While independent climate mechanisms can be responsible for the observed trends, we explicitly focus on exploring volcanic eruptions as a possible leading driver. A consistent agreement across all proxies is lacking in the pre-tephra record, yet sulfur enrichment and acidification processes allow us to suggest volcanism as a plausible trigger. Combined with the post-tephra cooling, the two sedimentary records depict a possible scenario of multi-decadal, continuous volcanic impact. • A single Saksunarvatn Ash layer was detected in two varved lake cores from N-Germany. • The ash layers in the two cores are dated to 10,282 ± 45 and 10,264 ± 24 cal. BP. • Palynological and geochemical analysis were conducted in proximity of the ash layers. • Environmental disturbance, possibly linked to volcanism, predates the ash fallout. • Evidence for a ca. 15-year-long cooling is recognizable after tephra deposition. [ABSTRACT FROM AUTHOR]

The timing, duration and evolution of sea level during the Marine Isotope Stage 5e (MIS 5e) highstand is a subject of intense debate. A major problem in resolving this debate is the difficulty of chronologically constraining the sea level fall that followed the peak of the highstand. This was mainly controlled by ice-sheet dynamics, the understanding of which is relevant for assessing future sea-level behavior due to global warming. Here we use stratigraphical and geochoronological (U/Th dating and tephra fingerprinting) evidence from the Infreschi archaeological cave (Marina di Camerota, Southern Italy) to constrain relative sea level (RSL) evolution during the MIS 5e highstand and younger stages. Uranium-thorium dating of speleothem deposition phases places the maximum highstand RSL at 8.90 ± 0.6 m a.s.l., as indicated by the near-horizontal upper limit of Lithophaga boreholes measured for along a ∼3.5 km coastal cliff section. Geochronological data show that RSL fell more than 6 m before ∼120 ka, suggesting a duration of the Last Interglacial highstand significantly shorter than proposed in some previous studies. Modelling shows that the RSL trend predicted by the ICE-5G and ICE-6G ice-sheet simulations is consistent with our data, but requires an additional significant reduction of both Greenland and Antarctic ice sheets to match the height of the local maximum highstand if no correction for tectonics is applied. Reconciling field data and models requires an earlier and likely shorter duration of the MIS 5e highstand. This suggests that our new data can constrain global ice-volume variations during the penultimate deglaciation, as well as glacial inception at the end of the Last Interglacial. According to our chronology, there is no local evidence of higher-than-present-day sea levels after 120 ka. • Infreschi cave data indicate that maximum highstand during MIS5e was ca. 8 m asl. • Infreschi cave data indicate RSL dropped of more than 6 m before 120 ka. • Infreschi cave data indicate that there is no evidence of RSL higher than present after 120 ka. [ABSTRACT FROM AUTHOR]

The Saksunarvatn Ash, first found in the Faroe Islands, is a tephra produced by the Grímsvötn volcanic system in Iceland. Since its discovery in the Faroe Islands, dark tephra with a similar stratigraphic position has been described at numerous locations around the North-Atlantic region; including 46 sites in Iceland (soil and lake sediments), 37 marine sediment cores from the North-Atlantic, 23 terrestrial locations in northern Europe (Faroe Islands, Scotland, Orkney, Shetland, Norway and Germany), and 4 sites from the Greenland Ice Sheet. The chemical composition of the tephra found around the North-Atlantic is, in most cases, within the published chemical range of the Saksunarvatn Ash originally found in the Faroe Islands, i.e. tholeiitic basalt with MgO and K 2 O wt% that places it in the more evolved part of the Grímsvötn chemical field. Published ages of the inferred Saksunarvatn Ash range significantly, dating from 10,625 ± 53 to 9586 ± 315 cal yr BP, although the widespread usage of the ice-core age of ~10,300 yr BP has given the tephra high chronological importance. Based on the reported sites, the tephra covers an area of about 2 million km2. However, in the last decade new studies have shown that the Grímsvötn volcanic system produced several widely distributed tephra layers of very similar chemical composition in the time period from 10,400–9900 yr BP. Hence, the Saksunarvatn Ash appears to be one of multiple early Holocene Grímsvötn tephra layers distributed around the North-Atlantic area. Where such tephras are identified, they therefore reflect a time interval rather than a precise marker as previously anticipated. Although still chemically indistinguishable, these Grímsvötn tephra layers represent a marker horizon around the North-Atlantic region spanning approximately 500 years, and are referred to as the G10ka series tephra. The exact number of eruptions that form the tephra marker horizon remains unknown, but up to seven have been proposed. • A basaltic tephra, the Saksunarvatn Ash, was described in the Faroe Islands in 1986 CE • The tephra was dated and became a widely-used marker layer in the North-Atlantic. • Recent findings show that the tephra reflects more than one eruption from Grímsvötn. • The new marker horizon is named the G10ka series tephra, including the Saksunarvatn Ash. • The age of the G10ka series tephra is 10.4 to 9.9 ka. [ABSTRACT FROM AUTHOR]