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While glacial remnants in the form of viscous flow features in the mid-latitudes of Mars are considered to be cold-based in the present-day, an increasing amount of geomorphic evidence suggests that at least some flow features were previously wet-based or had a mixed thermal state (polythermal) at during their evolution. Many of the viscous flow features known as glacier-like forms have been observed to emerge from alcoves that appear similar to cirques on Earth. Terrestrial cirques are typically characterized by a concave basin connected to a steep backwall. Cirques are expected to form from depressions in mountainsides that fill with snow/ice and over time support active glaciers that deepen the depressions by wet-based glacial erosion. To assess which alcoves on Mars are most "cirque-like", we mapped a population of ~2000 alcoves in Deuteronilus Mensae, a region in the mid-latitudes of Mars characterized by mesas encompassed by glacial remnants. Based on visual characteristics and morphometrics, we refined our dataset to 386 "cirque-like alcoves", which is five times the amount of glacier-like forms in the region, and used this to assess the past extent and style of glaciation on Mars. Using high resolution imagery, we find geomorphic evidence for glacial occupation associated with the cirque-like alcoves, including crevasse-like features, surface lineations, polygonal terrain, and moraine-like ridges. We propose that the cirque-like alcoves with icy remnants similar to rock glaciers on Earth represent a late stage of glacier-like form evolution. We also outline stages of cirque-like alcove evolution, linking a potential early stage of cirque-like alcoves to gully activity. On a population-wide scale, the cirque-like alcoves have a south to southeastward aspect bias, which may indicate a requirement for increased insolation for melting to occur and a connection to gullies on Mars. While the alcoves also have similarities to other features such as landslide scarps and amphitheater-headed valleys, the cirque-like alcoves have unique morphologies and morphometrics that differentiate their origin. Assuming warm-based erosion rates, the cirque-like alcoves have timescales consistent with both glacier-like forms and other viscous flow features like lobate debris aprons, whereas cold-based erosion rates would only allow the older timescales of lobate debris aprons. We propose that based on the geomorphic features and southward aspect, cirque-like alcove formation is more consistent with warm-based glaciation. [ABSTRACT FROM AUTHOR]

Alpine glaciers in the western United States are often associated with late-Holocene Little Ice Age (LIA) advances. Yet, recent studies have shown many of these glacial landforms are remnants of latest-Pleistocene retreat with only the most cirque-proximal moraines preserving LIA activity. Additionally, the timing and magnitude of glacial advances during the Neoglacial-LIA interval remains uncertain with presumed maximum extents occurring during the LIA driven by lower Northern Hemisphere insolation levels. Here we present Be surface exposure ages from a glacial valley in the Beartooth Mountains of Montana and Wyoming, United States. These new data constrain the presence of the glacier within 2-3 km of the cirque headwalls by the end of the Pleistocene with implications for large-scale retreat after the Last Glacial Maximum. Cirque moraines from two glaciers within the valley preserve a late-Holocene readvance with one reaching its maximum prior to 2.1 ± 0.2 ka and the other 0.2 ± 0.1 ka. Age variability among the moraines demonstrates that not all glaciers were largest during the LIA and presents the possibility of regional climate dynamics controlling glacial mass balance. [ABSTRACT FROM AUTHOR]

Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding the relationships between global climate and sea-level change and to testing numerical ice sheet models. In this study, we integrate recently acquired high-resolution 2D seismic reflection and borehole datasets from two wind-farm sites offshore of the Netherlands to investigate the sedimentary, geomorphological, and glaciotectonic records left by the Saalian Drenthe substage glaciation, when Scandinavian land ice reached its southernmost extent in the southern North Sea (ca. 160 ka, Marine Isotope Stage 6). A complex assemblage of glaciogenic sediments and glaciotectonic structures is buried in the shallow subsurface. The northern wind-farm site revealed a set of NE–SW-oriented subglacial meltwater channels filled with till and glaciofluvial sediments and an E–W-trending composite ridge with local evidence of intense glaciotectonic deformation that denotes the maximum limit reached by the ice. Based on the identified glacial geomorphology, we refine the mapping of the maximum ice sheet extent offshore, revealing that the ice margin morphology is more complex than previously envisaged and displaying a lobate shape. Ice retreat left an unusual paraglacial landscape characterised by the progressive infilling of topographic depressions carved by ice-driven erosion and a diffuse drainage network of outwash channels. The net direction of outwash was to the west and southwest into a nearby glacial basin. We demonstrate the utility of offshore wind-farm data as records of process–form relationships preserved in buried landscapes, which can be utilised in refining palaeo-ice sheet margins and informing longer-term drivers of change in low-relief settings. [ABSTRACT FROM AUTHOR]

The southern Black Forest was temporarily covered by a ∼1000 km 2 large ice cap during the Late Pleistocene. However, during the last glaciation maximum in the Alps the atmospheric circulation over Europe was presumably characterised by the advection of humid air masses from the Mediterranean Sea. As a consequence, the ice cap of the Black Forest was likely in a leeward position due to its location north of the Alps. This raises the question of whether it reached its last maximum extent simultaneously with the glaciers in the Alps. As modern dating techniques have hitherto not been applied to the southern Black Forest, the timing of the last local glaciation maximum remains poorly constrained. As a first step towards an independent regional glacier chronology, we present a critical re-examination of glacial landforms in the area north-west of the highest summit of the Black Forest (Feldberg, 1493 m a.s.l.). It relies on both the analysis of remote sensing data and field mapping. The review of previous studies highlights important disagreements regarding the location of ice-marginal positions and their correlation. In addition, our findings challenge earlier studies on the glaciation of the Black Forest: some previously described ice-marginal positions could not be confirmed, whereas some of the newly identified moraines are described for the first time. This highlights the need for detailed geomorphological investigations prior to the application of geochronological methods. A multi-ridged series of terminal moraines in one of the studied valleys, Sankt Wilhelmer Tal, is proposed as the main target for future dating. Due to discrepancies with earlier studies, future efforts should reinvestigate other key areas related to the last glaciation of the southern Black Forest. Kurzfassung: Der südliche Schwarzwald war während des Spätpleistozäns zeitweise von einer etwa 1000 km 2 großen Eiskappe bedeckt. Während des letzten glazialen Maximums in den Alpen war die atmosphärische Zirkulation über Europa jedoch wahrscheinlich durch eine Zufuhr feuchtebringender Luftmassen aus dem Mittelmeergebiet geprägt. Demnach lag die Eiskappe des Schwarzwaldes vermutlich im Lee der Alpen. Es stellt sich somit die Frage, ob die Ausdehnung der Eiskappe des Schwarzwaldes synchron mit den Alpengletschern ihr letztes Maximum erreichte. Da moderne Methoden der Altersbestimmung im Südschwarzwald bisher noch nicht eingesetzt worden sind, ist der Zeitpunkt des letzten lokalen glazialen Maximums derzeit schlecht erfasst. Als erster Schritt zu einer unabhängigen regionalen Gletscherchronologie präsentieren wir eine kritische Bewertung bisheriger Studien zu Spuren der Vergletscherung nordöstlich der höchsten Erhebung des Schwarzwaldes (Feldberg, 1493 m ü. NHN). Diese beruht sowohl auf der Auswertung von Fernerkundungsdaten als auch auf Feldkartierungen. Die Betrachtung der Ergebnisse bisheriger Studien unterstreicht teilweise deutliche Unterschiede in Bezug auf die Lage von Eisrändern und deren Korrelation. Zusätzlich zeigt diese Arbeit Diskrepanzen zu früheren Untersuchungen auf: einige der beschriebenen Eisrandlagen konnten nicht bestätigt werden, während in dieser Arbeit andere Endmoränen zum ersten Mal erwähnt werden. Dies zeigt die Notwendigkeit von sorgfältigen geomorphologischen Untersuchungen vor der Anwendung geochronologischer Methoden. Eine Serie mehrerer Endmoränenwälle in einem untersuchten Tal, dem Sankt Wilhelmer Tal, wird als Zielobjekt zukünftiger Datierungen vorgeschlagen. Aufgrund der offensichtlichen Diskrepanzen zu früheren Studien sollten zukünftig weitere Schlüsselgebiete der letzten Schwarzwaldvergletscherung geomorphologisch neu untersucht werden. [ABSTRACT FROM AUTHOR]

Absent glacial erosion, mountain range height is limited by the rate of bedrock river incision and is thought to asymptote to a steady-state elevation as erosion and rock uplift rates converge. For glaciated mountains, there is evidence that range height is limited by glacial erosion rates, which vary cyclically with glaciations. The strongest evidence for glacial limitation is at midlatitudes, where range-scale hypsometric maxima (modal elevations) lie within the bounds of Late Pleistocene snow line variation. In the tropics, where mountain glaciation is sparse, range elevation is generally considered to be fluvially limited and glacial limitation is discounted. Here we present topographic evidence to the contrary. By applying both old and new methods of hypsometric analysis to high mountains in the tropics, we show that (a) the majority are subject to glacial erosion linked to a perched base level set by the snow line or equilibrium line altitude (ELA) and (b) many truncate through glacial erosion towards the cold-phase ELA. Evaluation of the hypsometric analyses at two field sites where glacial limitation is seemingly marginal reveals how glaciofluvial processes act in tandem to accelerate erosion near the cold-phase ELA during warm phases and to reduce their preservation potential. We conclude that glacial erosion truncates high tropical mountains on a cyclic basis: zones of glacial erosion expand during cold periods and contract during warm periods as fluvially driven escarpments encroach and destroy evidence of glacial action. The inherent disequilibrium of this glaciofluvial limitation complicates the concept of time-averaged erosional steady state, making it meaningful only on long timescales far exceeding the interval between major glaciations. [ABSTRACT FROM AUTHOR]

This article discusses the last Pleistocene glaciation of the Black Forest region in southern Germany. The study aims to understand the timing and dynamics of the glaciation and its relationship to atmospheric circulation patterns and precipitation. The researchers used digital elevation models and field surveys to map glacial landforms and conducted cosmic-ray exposure dating to determine the ages of moraines and boulders. The results suggest that the glaciers in the Black Forest reached their maximum extent at different times than the glaciers in the European Alps. The study highlights the need for further research to reconstruct the climate history of the region and extract climatic signals from glacier data. [Extracted from the article]

Recent climatic warming has resulted in rapid retreat of glacier margins in the northern hemisphere exposing landforms which record changes in glacier extent and behaviour through their sedimentology and geomorphology. These modern glacial systems can be used as analogues for paleoglacial deposits, such as those found throughout Europe, Canada and the northern USA. Large ice sheets that covered land masses in the northern hemisphere during the Quaternary are known to have hosted fast-flowing ice streams that controlled ice dynamics and behaviour. However, the former positions of these ice steams are difficult to determine in paleoglacial deposits. This study focuses on documentation of sedimentological and geomorphological characteristics of the proglacial fields of western Slettjökull and Öldufellsjökull, northern outlet glaciers of the Mýrdalsjökull Ice Cap in southern Iceland. These glaciers were selected as they have both experienced periodic episodes of fast ice flow and rapid marginal advance (surges) during the last century. It is believed that surging ice margins can be used as analogues for rapidly moving paleoice streams common within the Laurentide and Scandinavian Ice Sheets during the last glaciation. A combination of landsystem analysis, whereby landforms are classified into genetically related landform-sediment assemblages, and architectural element analysis (AEA), a hierarchal method of examining sedimentary deposits, is applied in this study. This methodology allows a detailed model of the process-form relationship of landforms and sediments exposed in front of the retreating glaciers to be created. Initial mapping of the proglacial fields of Sléttjökull and Öldufellsjökull was completed using high resolution digital elevation models (DEM) obtained from the Icelandic Meteorological Office to investigate the types, scale and distribution of glacial landforms. These maps were ground checked in the field using a portable geographic information systems (GIS) unit. Sedimentological data were collected from exposures along river banks and terraces to identify the sediment types associated with different landform types. An unmanned aerial vehicle (UAV) was also used to collect high resolution imagery of the proglacial fields, focusing in particular on areas impacted by the most recent surge events. Field and remotely sensed data were combined into a GIS to examine the spatial relationship between the various landforms and their associated sediments. The proglacial fields of these two outlet glaciers show overall similarities in the distribution and morphology of landsystems tracts connected with end moraine development. However, the proglacial field of Sléttjökull has a larger sandur proximal to the glacier margin and a greater amount of glaciofluvial sediment compared with Öldufellsjökull. The areas of the proglacial fields impacted by surges that occurred in the 20th century show a distribution of landforms that is similar to that described from other surge-type glaciers, including hummocky terrain and kettle holes. However, these proglacial fields lack the prominent glaciotectonized end moraine frequently reported at surge-type glaciers. The model developed for these proglacial fields may be utilized to help identify areas affected by fast-flowing ice and the position of former ice streams in previously glaciated regions. [ABSTRACT FROM AUTHOR]

Marine Isotope Stage 2 (MIS 2) is the latest glacial period and includes the Last Glacial Maximum, which is known as the period when global ice volume reached its maximum and global temperature lower than today. An advantage of MIS 2 is the availability of radiocarbon dating to make it possible to compare sea-level data with other paleoclimatic proxies. However, the number and accuracy of sea-level records during MIS 2 is currently lacking. Here we present the history of MIS 2 sea-level and ice-sheet change as recorded in the Bonaparte Gulf, northwestern Australia, by reconstructing relative sea level and then modeling glacial isostatic adjustment. The isostatically-corrected global sea-level history indicates that sea-level plateaued around 23 cal kyr BP prior reaching its minimum (~19 cal kyr BP). These large changes in ice volume over such a short time indicates that the continental ice sheets never reached their isostatic equilibrium during the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]

The maximal extent of the Laurentide Ice Sheet (LIS) on eastern Baffin Island during the Last Glacial Maximum (LGM; about 20 000 years ago) has been widely debated during the last decades as different palaeo-glaciological models have been proposed. Spatial and temporal variability of ice sheets extension during Quaternary glaciations complicate the establishment of a reliable reconstruction of the ice margin. Furthermore, the lack of geophysical data in most of the fjords, and seaward, makes it difficult to reconcile the proposed terrestrial and marine glacial margins. Here we use high-resolution swath bathymetry imagery, combined with acoustic stratigraphy data and sediment cores collected during various oceanographic expeditions, focusing on the ice dynamics in the area of Clyde Inlet since the LGM. Our data reveal possible positions of the maximal extent of the LIS near the continental shelf edge. The deglaciation on the shelf was rather slow and episodic, as indicated by the presence of grounding-zone wedges, recessional moraines, as well as time-transgressive glacial lineations. Ice retreat in the fjord occurred more rapidly, most likely due to increased water depths. However, the presence of multiple moraine systems reveals periods of ice-margin stabilizations. This study provides additional information to the terrestrial data and, thus, helps improve the models of glacial dynamics in the northeastern sector of the LIS. [ABSTRACT FROM AUTHOR]

A complex ice stream network occupied the European Alps during the last glacial maximum (LGM, MIS 2, Würmian Pleniglacial) with large valley glaciers extending as piedmont lobes into the northern and southern forelands. A completely different situation is reported for the easternmost Alps, where only a patchy pattern of isolated glaciers, confined to minor valleys, localized cirques and small plateaus could develop. Although the Alpine LGM glaciation was intensively studied, data sets vary considerably in the easternmost Alps (e.g concerning the numbers of local glaciers as well as extents) and systematic analyses of the glacial record are missing for the entire region. Consequently, equilibrium line altitudes (ELAs) and ELA depressions (ΔELAs) for these paleo glaciers remain unknown as well, though such data can be extremly useful to provide information on the variance of atmospheric circulation patterns over glacial to interglacial timescales. Characterized by relatively simple geometries and obviously rather simple source area relations (compared to the ice-stream network in the central Alps), they are most suitable for paleo-glacier reconstruction and ELA modelling – and can provide a robust dataset on ELA depression variabilities during the LGM. Such analysis is hardly possible for the ice-stream network occupying most of the central Alps at the same time.To fill this gap, we provide a new GIS-dataset of the LGM glaciation at the Eastern Alps based on the principal work of van Husen (1987), a number of case studies, geological maps, and the analyses of multiple orthophoto and DEM data. First systematic analyses on ELAs and ELA depressions of these low elevated isolated glaciers highlight the highly variable glacier response across the Eastern Alps to topographic and climatic forcing. [ABSTRACT FROM AUTHOR]

Located between Melville Peninsula and northwestern Baffin Island (69.9247° N, 84.5121° W), the Fury and Hecla Strait region plays a key role in the understanding of the postglacial evolution of the Canadian Arctic. The absence of paleolimnological data in the region as well as the strategic position of the strait itself, given its location at the junction of the Atlantic Ocean currents coming from Foxe Basin and those of the Pacific Ocean through the Gulf of Boothia, make it a prominent region for Quaternary research. Although some studies have suggested a timing for the regional deglaciation, results remain extrapolated and do not provide high-resolution data for the region. This project aims to analyze sediment cores of lakes located on the southern shore of the Fury and Hecla Strait, in the Canadian Arctic, in order to reconstruct past climates and landscapes since the end of the last glacial period. A multi-proxy approach based on physical, chemical and biological core parameters, allowed high-resolution paleoenvironmental reconstructions of the region, including natural climate fluctuations, past extreme climate events and major landscape changes induced by glacial retreat, marine inundation and glacial isostatic readjustment.Various radiometric dating methods (210Pb, 137Cs and 14C) were used to establish a chronology for the reconstructed changes, pointing towards a glacio-marine phase that lasted from 8250 cal. BP, at its latest, to 6675 cal. BP, followed by a gradual transition towards freshwater conditions and the establishment of a lacustrine phase at 6125 cal. BP. An extreme event, marked by major geochemical and sedimentological shifts, also appears to have happened at 3950 cal. BP, but the nature of this abrupt change remains unknown. The results were also correlated with regional temperature data from previous studies to explore the relationship between diatom assemblage changes and environmental fluctuations. This study is crucial to respond to many unsolved questions in oceanography, biogeography, genetics or even anthropology, by providing a high-resolution chronology of geophysical changes, namely regional deglaciation and the opening of the strait. Furthermore, it improves our understanding of paleoenvironmental variability in the Foxe Basin throughout the Holocene, including climatic and physico-chemical shifts, enabling us to predict ecosystem responses to future global change. [ABSTRACT FROM AUTHOR]

Although it is well documented that the late Paleozoic experienced one of the most severe ice ages of Earth's history, the exact timing and frequency of glaciations is still debated. This is in part due to the difficulty of accurately dating glacial deposits that are often barren, with no faunal recovery, and riddled with stratigraphic hiatuses. In order to circumvent these limitations, one alternative way to reconstruct the evolution of grounded ice volume during the Early Carboniferous is to use far-field reconstruction of eustatic sea-level fluctuations.In this study, we report on a detailed sedimentological investigation of Early Carboniferous strata from Western Libya. In the Late Paleozoic, this region was part of the Saharan platform, on the Northern margin of Gondwana, that formed a widespread, extremely low-angle, tectonically stable ramp. During the Early Carboniferous, extensive and thick exposures of siliciclastic-dominated sediments were deposited along a N-S orientated outcrop belt, parallel to depositional dip.A total of 4800m of sedimentary section was logged over a ca. 400km-long transect. Fieldwork observations and integrated subsurface data allow establishment of a detailed sequence stratigraphic framework. During the Tournaisian, Visean and Early Serpukhovian, six lowstand system tracts are identified, composed of incised valleys filled with fully amalgamated fluvial sandstones, capped by open marine packages. These incised valleys can reach a thickness of 50m. Given that they are embedded within shoreface to offshore marine deposits, total sea-level fluctuations of at least 70-80m can be estimated from these deposits. Due to the stable tectonic nature of the Saharan Platform during the Early Carboniferous, glacio-eustasy is the most-likely explanation for the origin of the observed scale of sea-level fluctuations, pointing at the onset of incipient Late Paleozoic glaciation during the earliest Visean. This is compatible with published evidence of Visean glacial deposits in Southern Sahara and South America, further inland on the Gondwanan margins. Ice sheet retreat is probably the mechanism responsible for contribution of the large volume of coarse continental clastics that initially fill the valleys exclusively with fluvial facies, preserved by the followed rapid transgression associated with ice melt.In line with paleotemperature reconstruction, our study indicate that the Late Paleozoic Ice Age has started prior to what is generally depicted in the literature. The location of the study area, on a stable passive margin, provides confidence in the mechanism controlling the incision, and the results provide improved resolution that offers an insight into the scale and frequency of glacial cycles in the Visean. [ABSTRACT FROM AUTHOR]

Glacial cirque landforms are the result of glacier erosion on mountain ridges and they are repeatedly activated on every glaciation. Cirque distribution is largely determined by climatic patterns during periods of glacier initiation, whilst their dimensions are largely determined by glacial erosion over tens of thousands of years (continued in successive glacial cycles), which is likely maximised during the onset and termination of periods of glaciation (Barr and Spagnolo 2015). Glacial cirque morphometry has been widely used in revealing glaciation climatic patterns (Barr et al. 2017).In this contribution, the ACME GIS toolbox for ArcGIS (Spagnolo et al. 2017) was used to calculate glacial cirque morphometry in manually mapped glacial cirques N and NW of the Iberian Peninsula. Given that several mountain areas in N and NW of Iberian Peninsula are below the regional Late Quaternary ELA, only areas were Quaternary glaciation has been identified and described were used. A total of 445 cirques were mapped. A 5 m. pixelsize national DEM provided the surface data. The amount of cirque population makes us confident enough to dismiss the influence of topography, lithology or geological structure on the statistically relevant results.Results show an unsurprising NW-SE cirque floor altitude increase pattern, which is concomitant to Quaternary ELA distribution. Cirque orientation shows a N-NE preference, which we interpret as temperature-driven, confirming that glaciation was marginal during a long period of the Quaternary. Cirque depth and shape shows larger, deeper and rounder cirques located in mountain ranges well above the ELA, where cirques have been active for longer. Glacial cirque morphometry has proved to be valuable as palaeoenvironmental tool only if a large population of cirques is considered. The study area for this contribution -the entire Cantabrian Range- and the amount of cirques mapped, can be seen as a minimum thresholds for achieving reliable conclusions. Therefore, only through the use of automatic calculation methods, these studies can be performed in a cost-effective way. I would like to stress the possibilities that ACME has for morphometric analysis on glacial and non-glacial landforms, such as cirques, drumlin, esker, landslides or meanders. Also, I would like to point to automatic or semi-automatic mapping tools as the way forward in the geomorphological mapping research field. [ABSTRACT FROM AUTHOR]

We present a geomorphological assessment of the extent and dynamics of glaciation in the Wicklow Mountains, Ireland, during the Last Glacial Interglacial Transition (LGIT; ~ 20 – 11 ka BP). Previous research has established the existence of a local ice cap, confluent with regional ice at the Last Glacial Maximum (LGM; ~ 25 ka BP). However, there has been little consideration of ice retreat in response to climate amelioration during the LGIT. Here, we investigate ice dynamics during and after the transition from an ice cap to topographically restricted mountain glaciation. The geomorphological record indicates that initial ice cap recession was characterised by rapid retreat and large-scale disintegration, with ice masses only stabilising once topographically constrained within valleys. Following fragmentation of the LGM ice cap, three distinct landsystems were established in the Wicklow Mountains: (1) the large north-eastern sector of the region hosted a mountain icefield with multiple outlet glaciers; (2) a small plateau icefield existed in the central sector, with several outlet glaciers; and (3) several individual valley glaciers persisted in the south-western sector. Each of these landsystems document sustained retreat and subsequent stabilisation during the LGIT, prior to the Younger Dryas. Two-dimensional reconstructions of ice dynamics indicate variations in recession patterns throughout the region. Based on our ice margin reconstructions and the limited published dates for the region, we suggest that following the retreat of regional ice after the LGM, the local ice cap was relatively stable until the start of the LGIT (~20 ka BP). After this, ice experienced sustained thinning and ice margin retreat until ~ 17 ka BP. By this point, ice was topographically restricted and the three aforementioned landsystems established. A period of ice margin stabilisation occurred before further persistent retreat until ~ 15 ka BP, by which time ice had retreated into the upper reaches of valleys. It is likely that the plateau icefield and most of the mountain icefield had disappeared by ~15 ka BP, when the outlet glaciers of both landsystems had detached from their central accumulation areas and experienced sustained retreat. Following this, some small cirque glaciers experienced minor readvance before ice recession continued. The geomorphological record indicates that it is likely that glacial ice disappeared in the Wicklow Mountains during this period but was re-established, in a small number of cirques, during the Younger Dryas. [ABSTRACT FROM AUTHOR]

High-latitude trough mouth fans are high-resolution paleoclimate and ice-sheet monitors, and allow a continuous reconstruction of climate and sedimentary processes active during glacial-interglacial cycles. The North Sea Fan is located on the northern North Sea margin and is built-up by c. 40,000 km3 of sediments dominated by the erosional products of the Norwegian Channel Ice Stream. The aims of this contribution are (i) to characterize the sediments deposited in the North Sea Fan, and (ii) to do a three-dimensional reconstruction of the processes involved into the formation of the North Sea Fan. We use 16,000 km2 of high-resolution processed 3D seismic data collected in 2017 and 2018 from the proximal North Sea Fan. These data allow us to image the shallow subsurface in a resolution of 8 m vertically and 20 m horizontally. Fifteen horizons have been picked with an in-line spacing of 150 m, followed by gridding, horizon attribute extraction, sediment volume calculations, and seismic geomorphological interpretation. Our results show that six sediment packages containing stacked glacigenic debris flows (GDFs) have been deposited at the upper slope of the North Sea Fan. The GDF package related to the last glaciation has a thickness of up to 400 m and is characterized by a homogenous seismic facies intercalated by five continuous high-amplitude reflections, which separate the package into six sub-units. The structure maps of these reflections show multiple sharp, SE-NW-oriented channels with well-developed levees and densely-spaced pockmarks. The GDF deposits have been removed from the upper slope by four megaslides, which are identified as deformed sequences bound by smooth lower and irregular upper surfaces. Negative-amplitude, continuous reflections at the base of the megaslides fade out uphill of the slide headwalls. The topography shaped by these megaslides is infilled by glacimarine deposits identified as low-amplitude, continuous reflections. Continuous reflections with mounded geometries, interpreted as contourites, characterize the deepest part of the fan. The GDF packages show that the Norwegian Channel Ice Stream reached the shelf edge during six marine isotope stages, and that the ice stream oscillated six times during the last glaciation. The up to 400 m thick GDF package related to the last glaciation has been deposited within 4 kyr, which correlates to a sedimentation rate of up to 100 m/kyr, and a sediment flux of 1500 km3/kyr for the study area. Channels identified at multiple levels within the GDF package indicate that the sediment delivery from the Norwegian Channel Ice Stream to the slope was continuous and did not occur in pulses of several decades. Channel-fed levees and debris lobes characterize the paleo-seafloor between the channels. The circular depressions, interpreted as pockmarks, indicate fluid escape events in some intra-channel areas during the deposition of the GDFs. Negative, high-amplitude reflections below the GDFs and megaslides indicate gas-charged sandy bases and show a strong correlation between pre-conditioned glacimarine glide planes and megaslide occurrence. Contourites at the base of the fan indicate different oceanic processes dominating the early Quaternary deposition. [ABSTRACT FROM AUTHOR]

Mars' present climate is extremely cold and arid. Until recently, it was widely thought that debris-covered glaciers in Mars' mid-latitudes have been pervasively cold-based since their formation 10s–100s Myr ago. However, we recently discovered eskers associated with ~110–150 Myr old glaciers in the Phlegra Montes [1] and NW Tempe Terra [2] regions of Mars' northern mid-latitudes. Eskers are sinuous ridges comprising sediments deposited in glacial meltwater conduits. Therefore, eskers associated with existing mid-latitude glaciers on Mars indicate that localised wet-based glaciation did occur during Mars' most recent geological period. Eskers are important tools for reconstructing the nature, extent, and dynamics of wet-based glaciation on Earth, and have similar potential for Mars.We used 1–2 m/pixel resolution digital elevation models derived from 25–50 cm/pixel High Resolution Imaging Science Experiment stereo-pair images to measure the planform and 3D morphometries of the Phlegra Montes and NW Tempe Terra eskers, and compare them with the morphometries of Quaternary-aged eskers in Canada [3] and SW Finland [4]. We found that the Martian eskers have remarkably similar lengths, sinuosities and heights to terrestrial eskers, but that the Martian eskers are typically wider and have lower side slopes. Large width-height ratios of the Martian eskers are consistent with our previous measurements of ancient (~3.5 Ga) eskers close to Mars' south pole [5], and may arise from differences in either: esker degradation state, or fundamental glacio-hydrological controls on esker formation between Mars and Earth. Portions of the two Martian eskers with comparable crest morphologies (e.g., sharp- or round-crested) have similar width-height relationships, suggesting that glacio-hydrological processes may exert controls upon the observed relationships between esker morphology and morphometry.Our morphometric analyses also reveal that the Martian esker in NW Tempe Terra has a 'stacked' morphology: the crest of a wide, round-crested underlying ridge is superposed by a narrow, sharp- to multi-crested ridge. Based on morpho-sedimentary relationships observed along terrestrial eskers [6], we interpret this transition to represent waning sediment supply and meltwater discharge towards the end of the esker-forming drainage episode(s). Direct sedimentary insights into Martian eskers are not yet possible so we emphasise that such inferences should be rigorously grounded in observations of analogous landforms on Earth.This work was funded by STFC grant ST/N50421X/1.References: [1] Gallagher, C., and Balme, M.R., (2015), Earth. Planet. Sci. Lett. 431, 96-109, [2] Butcher, F.E.G., et al. (2017), J. Geophys. Res. Planets. 122(12), 2445-2468, [3] Storrar, R.D., et al. (2014) Quat. Sci. Rev. 105, 1-25, [4] Storrar, R.D., and Jones, A., Unpublished, [5] Butcher, F.E.G., et al. (2016), Icarus 275, 65-84, [6] Burke, M.J., et al. (2010) Geol. Soc. Am. Bull. 122, 1637-1645. [ABSTRACT FROM AUTHOR]

The high-altitudinal plateaus of Jotunheimen in central South Norway, the mountain region home of Norway's highest summits, create a unique and diverse natural environment. The specific gross morphology of Jotunheimen facilitates the occurrence of a variety of periglacial landforms ranging considerably in both dimension and age. The regional distribution of permafrost is one of the major controlling factors for the altitudinal distribution of these periglacial landforms. The largest individual features of patterned ground, undisputed the regionally most dominant periglacial landforms, are situated on terrain currently underlain by permafrost. They visually appear to be quite relict, despite the occurrence of permafrost, and the exact timing of their formation remains unknown. This example points to additional factors significantly influencing the periglacial landform assemblage, like topography, ground moisture availability, and the local deglaciation history. The lack of a regional overview regarding periglacial landforms in Jotunheimen exacerbates the need for a profound investigation of their altitudinal zonation and potential causal links to climate, permafrost, (de-)glaciation, and other factors.The compilation of a regional overview based on aerial imagery and a literature review aims, therefore, to reveal further insight into the controlling factors for and mechanisms of periglacial landform development in Jotunheimen. This shall be achieved by creating an altitudinal zonation for periglacial features and highlighting causal links between their spatial/altitudinal distribution and possible influencing factors. In an outlook to future studies this attempt may also provide more detailed information on the regional basal properties of the former Scandinavian ice sheet, the regional/local deglaciation patterns for the Jotunheimen region, and about the exact chronology of formation of the periglacial landforms studied. [ABSTRACT FROM AUTHOR]

Aim of the research: In general, marine terraces are covered by later non-marine deposits and difficult to obtain former shoreline using disturbed terrace surfaces. Precise determination of the former shoreline could be obtained from geological analysis of marine terrace deposits. Numbers of tight drilling have done to establish new method for terrace analysis.Study area and geology: Japan Sea side margin of the Shakotan Peninsula and the southern region, Hokkaido, Japan. MIS5e Marine Terrace deposits which are mainly composed of well sorted shore sand and gravels associated with volcanic ash, Toya (erupted about 115,000 years ago) in the upper most part of the deposits. The terrace deposits (1 to 4m) are covered by thick talus deposits (5 to 30m) formed by periglacial process.Method of terrace analysis: 7 sections across the MIS5e Terrace were selected. 4 to 8 tight drilling in individual sections, total numbers of 32(total length 456m) drilling have done. Buried wave-cut bench and sea cliff are reconstructed by distribution of the terrace deposits and the precise site of former shoreline was obtained.Results: Obtained altitudes of the former shoreline from the 7 sections are about the same 25m. Our research proofed that the MIS5e terrace surface is not inclined in the study area and the previous study was misinterpreted by the cover of talus deposits. In some areas, we were recognized three peat layers from drilling cores. The deposition rate obtained from the depth of some peat layer and the 14C dating value is approximately 0.3mm / yr. Events in the last glacial period were recorded. [ABSTRACT FROM AUTHOR]

Loess deposits cover 10% of the world continental surface and larger parts in Eurasia but are really limited in Mediterranean areas. In the Iberian Peninsula it has been described mainly in the central Tagus basin and in the Eastern Ebro basin besides other minor outcrops (Andalucia, la Mancha, Girona). These loess deposits have a great potential for climate interpretation that can illustrate environmental changes during the glacial cycles and record past global atmospheric mineral dust dynamics and palaeoenvironmental changes in the Mediterranean. The contribution of this work is to identify with more detail the distribution of loess in the Eastern Ebro basin to the boundary with the Prelitoral Catalan System, as a first step to locate their source areas and to understand their formation conditions and pedogenesis. The spatial distribution of loess outcrops is highly discontinuous over a surface of 2500 km2, and therefore it may be considered as the largest loess region in the Iberian Peninsula. These loess deposits overly the Tertiary sediments and the Quaternary terraces of the Central Ebro Valley and the Eastern Móra d'Ebre basin. Representative profiles with primary loess have been determined for the macromorphological characterization of the deposit. Samples were obtained for physico-chemical, particle-size, micromorphological analyses and OSL dating. From several possible source areas, samples were collected from terrace T2 of the Ebro River and from nearby tributaries (Cinca, Segre). Samples were also taken from Tertiary materials for textural analysis, grain-size distribution and heavy mineral analysis, to be compared with loess samples. The studied deposits are very sandy, formed by homogeneous silt and fine sands, are very porous and they form highly stable slopes. The particlse are composed of quartz (40-50%), calcite (30-40%) and other minerals as feldspars, biotites and muscovites besides accessory minerals. These sediments are carbonated (around 38% calcite) and contain very little organic matter (<0.05%). To the West of the area some outrcops contain gypsum (up to 28%). The relatively coarse grain size, mineralogy, distribution and depth indicate that the potential source areas are not very far, with a W-NW wind direction. They are probably found at alluvial valleys of the Central basin or at Chiprana endorheic basins and surrondings, where deflaction areas are found. The age of the deposits can be classified into two groups. Most of them were formed between 17-34 ky, which correspond to the cold Heinrich phases 1, 2 and 3 of the last Maximum (LGM). In a few cases older outcrops, with ages older than 115 ky, were probably deposited at the end of the penultimate glacial period and underwent pedogenesis during the Eemian warmer period. [ABSTRACT FROM AUTHOR]

The waterways and the portages connecting them played a huge role in the settlement and economic development of forest landscapes of the vast territory of the Center and the North of the Russian Plain. Since VIII - XI centuries, water transport and trade routes have been formed: "The Great Volga Route", "From the Varangians to the Greeks", Severodvinsk way and others.It was possible to move from one river basin to another in forest areas on the interfluves only by the shortest paths between the upper reaches of the rivers - the places of the transitions - portages, where boats, ships and cargoes were moved on dry land. The main signs of the direction to the portages on the forested difficult terrain were large boulders or their clusters, and with the adoption of Christianity, so-called "portage" crosses.The landscape analysis of the location of the portage pathways in the northern part of the Russian plain showed that most of them were confined to the nodal sections of the network of troughs of the glacial water flow in the marginal regions of the Quaternary glaciation. Currently, these areas are also the main watersheds of almost all the river systems of the Russian Plain. The portages were laid along small troughs of the runoff of glacial waters ("through valleys" or "inter-basin overflows"), occupied by residual lakes or upland bogs. These hollows connected the larger troughs of the runoff, in which, in the late glacial period, the upper reaches of the rivers were actually laid.Stone crosses were set as landmarks on waterways on key portages. These original traffic signs were created from granite, sandstone, limestone and other local materials with an average height of 1 to 2 m. One of the most famous crosses of the chronicles: Ignach cross (set no later than in 1238), which was on the watershed section of the "Seregersk waterway" on the Novgorod land. In 2003, a memorial sign was erected on its place on the territory of the Valdai National Park. The Sterzhensk cross on the Tver land (dated 1133) was established as a pointer to the confluence of the river Volga into the lake Sterzh. Today, the Sterzhensk cross is located in the Tver regional natural history museum. The portage crosses of the IX – X centuries are in the expositions of local history museums in the town of Ostashkov (Tver region) and in the town of Polotsk (Belarus). A unique stone landmark cross is kept in the Church of Mary Magdalene in the village of Parichi of the Svetlogorsk district in the Gomel region (Belarus). There are crosses that were preserved in their historical places of origin: for example, the portage cross at the Malskoye lake, which is 4 km from the town of Izborsk (Pskov region, Russia). At present, these monuments are reliable witnesses to the development of ancient waterways and are valuable objects of the natural and cultural heritage.The work is performed under the project of Russian Foundation for Basic Research № 19-05-00233, № 18-311-00222 [ABSTRACT FROM AUTHOR]

Producing three-dimensional palaeoglaciological reconstructions of discrete ice masses hasbeen the focus of many glacial geomorphological studies in the Scottish Highlands over thepast 15 years or so. Despite this, understanding of the extent, style and timing of Quaternaryglacier fluctuations in Scotland remains incomplete. This is exemplified by the enigmatic andcontentious Gaick (or Gaick Plateau), a dissected upland plateau in the Central Grampians.Previous studies of the glacial sediment-landform assemblages in this area have resulted inwidely-differing and conflicting interpretations, although the 'generally-accepted&#x2019;model is one of extensive plateau icefield glaciation during the Younger Dryas(∼12.9–11.7 ka). We present the results of renewed, systematic geomorphological andsedimentological investigations in the Gaick. Using a glacial landsystems approach,morphostratigraphic principles and 'glacierisation threshold&#x2019; analysis, we establish thatthe area experienced only spatially-restricted plateau icefield glaciation during theYounger Dryas. This contrasts starkly with the widely-held view that the Gaick wascovered by an extensive plateau icefield during the Younger Dryas. We use thegeomorphological evidence, together with surface profile modelling, to produce athree-dimensional reconstruction of a ∼42 km2 Younger Dryas plateau icefield. Thisnewly-reconstructed icefield is then used to derive palaeoclimatic variables for theYounger Dryas and assess regional climate trends across Scotland during that period. [ABSTRACT FROM AUTHOR]

Located in Asia where Russia, China, Mongolia, and Kazakhstan share a border, the Altai Mountains are composed by high ranges peaking at 4,506 m (Belukha), still glaciated large plateaus and deep valleys. With more than 1000 km², the Altai glaciers represent 50 % of the glaciated area of North Asia. Although because of repeated occurrences of glacial megafloods during the Pleistocene have been intensively studied in Russian Altai, the chronology and extent of its glaciations are poorly understood compared to other Central Asian regions.In relation with archaeological researches developed by the Russian-French team ARTEMIR, we investigated the upper Kalguty basin located in the south-eastern part of the Ukok Plateau, Russian Altai. Along the border with Mongolia, the elevation of this very dry area (100 mm/a) ranges from 2300 to 3500 m. Although current glacier area is < 0.25 km², many glacial landforms allow reconstructing past glaciations in the upper Kalguty basin. A detailed geomorphological study was carried out on the field in July 2015, and rock samples were taken on scoured bedrock and erratic boulders at one key site for surface exposure dating using in situ-produced cosmogenic nuclides.The maximal extent of the Kalguty valley glacier in the upper basin occurred shortly before 20.9 ka. As evidenced by moraines and kame terraces located higher on one valley side, larger and earlier, but not dated, glaciations occurred prior to the ~21 ka Kalguty Glacier advance. On the other hand, three morainic complexes testify to smaller advances corresponding to a reduced Kalguty glacier and two smaller valley glaciers. Reconstructed ELAs of these former glaciers were used to infer their Late Glacial extents ages and the corresponding regional palaeoclimatic conditions. The results regarding the chronology and extent of the Kalguty Basin glaciations since the LGM are discussed by relating them to other regional studies in the Altai Mountains and Central Asia. [ABSTRACT FROM AUTHOR]

Last Glacial Maximum reconstructions of former glacier in the European Alps shows large ice expansion on the northern side of the Alps, with wide piedmont lobes spreading over lowlands (synthese in Ehlers et al., 2011). The general chronological outline of the LGM in the Alps suggests a fairly synchronous glacial maximum around 26-20 ka (marine isotope stage 2; Wirsig et al., 2016), in line with global data from the Northern Hemisphere. However, a long lasting debate persists in French Alps regarding the timing of the Late Pleistocene maximum ice lobe extent in the Lyon area, varying from MIS 2 to MIS 4 based on indirect and contradictory radiocarbon ages (Mandier et al., 2003) and field constraints (Monjuvent and Nicoud, 1988). This debate was further rekindled by recent alpine ice modelling studies (Becker et al., 2016; Seguinot et al., 2018).A clear and robust chronological constrain of the Lyon glacial lobe extent is now critical as it would have major implication in terms of our understanding of past atmospheric circulation patterns. Traditional dating techniques such as radiocarbon and cosmogenic nuclides exposure are challenging in this area due to the scarcity of organic material incorporated within glacial deposits and the huge scarcity of in-place moraine boulders. In these circumstances, Optically Stimulated Luminescence (OSL) techniques, which allow the dating of buried sedimentary material, offer a promising alternative. In this study, we propose a new chronological reconstruction of the Lyon Lobe maximum extent during the Late Pleistocene. This chronology is based on new OSL data measured from fluvio-glacial deposits located in presently dry valleys only active during the Late Pleistocene maximum extent of the Lyon Lobe. Our preliminary results suggest that in fact, two major phases of glacial advance of similar extent occurred during the Last Glacial cycle, around the MIS 2 and around the MIS 4. These results not only bring a fresh contribution to the debate of the local paleoglacial history in the French Western Alps but may also have significant implications in terms of Late Pleistocene glaciations pattern and paleoclimate evolution in the Alps. [ABSTRACT FROM AUTHOR]

Research on mountain glaciations has a long history and in the light of current global change, they are increasingly recognised as highly important palaeoclimatic archives for the immediate and more distant geological past. One of the most important leaps forward with the investigation of mountain glaciations during the past 2 decades was substantial improvement achieved within the field of numerical age dating techniques, in particular progress of surface exposure dating using cosmogenic radionuclides (CRN). This development has definitely given the entire research field new momentum. Unfortunately, this methodological progress is in many cases not matched by the recommended necessary level of precautions regarding the interpretative steps with the reconstruction of Holocene glacier chronologies. Improved precision and accuracy with numerical dating techniques comes often with an increasing lack of attention with the geomorphological analysis of the dated landforms. With recent studies it has subsequently become more popular to outline moraines primarily based on individual CRN boulder age clusters without detailed geomorphological mapping or examination. Such an attempt has also been conducted on Holocene glacier forelands in Aoraki/Mt.Cook National Park where a substantial number of CRN boulders ages have been employed to identify and label numerous "moraines". Subsequently, arithmetic means of CRN ages for these apparent "moraines" were linked to individual glacier advances and palaeoclimatically interpreted accordingly. A sound geomorphological analysis of the studied glacier foreland does, however, reveal that this procedure is actually erroneous. Among the problems identified are (a) inclusion of hugely overprinted moraine remnants that lack proper characterisation, (b) wrong subdivision of moraine segments belonging to one defined individual moraines, and (c) mismatching of apparent CRN ages for moraine segments that morphologically need to correspond for any meaningful reconstruction of former marginal positions. A revision of this particular glacier chronology provides major implications for any subsequent palaeoclimatic interpretation as the number of reliably documented neoglacial events decrease from 9 to 5.The value of geomorphological analysis in the context of investigating mountain glaciations is, however, not primarily restricted to chronological approaches. It may also provide assistance with the conceptual context for mechanisms of deglaciation patterns or long-term landscape evolution. In the upper Waimakariri River catchment following a Late Glacial readvance dated to c. 17.5 ka ago, a lake dammed by the related moraine system and debris-covered dead ice should have existed for many centuries before it subsequently drained. That lake would naturally have influenced both the immediate deglaciation mechanism and landform evolution post-LGM. Despite introduced during the 1950s, the concept of this particular palaeo-lake has never been exposed to any detailed geomorphological analysis yet. Whereas the existence of a post-LGM palaeo-lake itself remains out of question, the proposed link to glacier retreat following a Late Glacial re-advance is unrealistic in light of a logical time sequence for individual elements of the local landform assemblage. The lake needs to be younger and postdate Deglaciation in this section of the Waimakariri River.Summarising, detailed geomorphological analysis is indispensable with any attempt to investigate mountain glaciations. [ABSTRACT FROM AUTHOR]