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A new chronology of the last glaciation is established for the Krkonoše (Giant) Mountains, Central Europe, based on in-situ produced 10Be in moraine boulders. Exposure ages and Schmidt Hammer rebound values obtained for terminal moraines on the northern and southern flank of the mountains suggest that the oldest preserved moraines represent early phases of the Last Glacial Maximum (LGM). Large moraines at the outlet of the Snowy Cirques (Śnieżne Kotły) and in the middle part of the Úpa (Obří důl) trough were deposited around 21ka while a series of smaller moraines above the LGM deposits represent readvances that occurred no later than 18.1±0.6ka, 15.7±0.5ka, 13.5±0.5ka and 12.9±0.7ka. An exposure age of 13.8±0.4ka obtained for protalus ramparts at the foot of the Úpská jáma Cirque headwall indicates that glaciers advanced only in north- to east-facing cirques during the Lateglacial. The last glacier fluctuation was synchronous with the Younger Dryas cold event. The timing of local glacier advances during the last glacial episode correlates with the late Weichselian glacier phases in the Alps and in the Bavarian/Bohemian Forest. [ABSTRACT FROM AUTHOR]

Coarse debris accumulations cover large areas in high latitude and mountain environments, but their age and origin remain mostly unknown. Here we reassess the morphology of a prominent coarse debris accumulation in the Sudetes Mountain range in central Europe and constrain its timing with 10Be surface exposure data. Our observations indicate that the landform in the south-eastern slope of the Suť ridge appears consistent with the morphology of a block slope. The oldest minimum age of 150.1 ± 4.8 ka obtained for the tor at the upper limit of the block slope indicates the disintegration of the ridge and surface lowering under periglacial conditions prior to the last glacial-interglacial cycle. Four exposure ages retrieved for block samples range from 84.3 ± 3.8 to 26.8 ± 2.6 ka, providing evidence for block emplacement during the last cold peri od. The exposure ages extend existing chronological dataset for peri/glacial landforms in the Sudetes and constrain the timing of cold environments in the area prior the Last Glacial Maximum. The ages are also consistent with surface exposure data reported for block fields and block slopes in Western Europe and confirm the formation of similar landforms over the last glacial period in the Sudetes. [ABSTRACT FROM AUTHOR]

10 Be exposure ages from moraines and bedrock sites in the Roháčská Valley provide chronology of the last glaciation in the largest valley of the Western Tatra Mts., the Western Carpathians. The minimum apparent exposure age of 19.4 ± 2.1 ka obtained for the oldest sampled boulder and the mean age of 18.0 ± 0.8 ka calculated for the terminal moraine indicate that the oldest preserved moraine was probably deposited at the time of the global Last Glacial Maximum (LGM). The age of this moraine coincides with the termination of the maximum glacier expansion in other central European ranges, including the adjacent High Tatra Mts. and the Alps. The equilibrium line altitude (ELA) of the LGM glacier in the Roháčská Valley, estimated at 1400–1410 m a.s.l., was 50–80 m lower than in the eastern part of the range, indicating a positive ELA gradient from west to east among the north-facing glaciers in the Tatra Mts. Lateglacial glacier expansion occurred no later than 13.4 ± 0.5 ka and 11.9 ± 0.5 ka, as indicated by the mean exposure ages calculated for re-advance moraines. This timing is consistent with the exposure age chronology of the last Lateglacial re-advance in the High Tatra Mts., Alps and lower mountain ranges in central Europe. The ELA in the Roháčská Valley estimated at 1690–1770 m a.s.l. in this period was located 130–300 m lower than in the north-facing valleys in the High Tatra Mts. 10 Be exposure ages obtained for a rock glacier constrains the timing of this landform stabilization in the Salatínska Valley and provides the first chronological evidence for the Lateglacial activity of rock glaciers in the Carpathians. [ABSTRACT FROM AUTHOR]

10 Be exposure age chronology of the last glaciation was established in a key area at the southern slopes of the High Tatra Mts., Western Carpathians. In-situ produced 10 Be in moraine boulders, glacially transformed bedrock surfaces and rockfall accumulations constrains the timing of the Last Glacial Maximum (LGM) glacier expansion and provides chronological evidence for the post-LGM decay of one of the largest paleoglaciers in the range. The uncertainty-weighted mean age of 22.0 ± 0.8 ka obtained for the terminal moraine in the forefield of the Velká Studená dolina Valley indicates that the oldest moraine was deposited close to the global LGM. This finding confirms that well-preserved moraines in the range were formed during the last glacial cycle and that glaciation on the southern flank of the range was more extensive than earlier in the last glacial cycle. The maximum glacier extent correlates with late Würmian/Weichselian glacier phases in the Alps, the Bavarian/Bohemian Forest and the Krkonoše Mts., but probably postdates the period of maximum glaciation in the Southern Carpathians. Re-advance moraines at the mouth of the Velká Studená dolina Valley and in the middle part of the Malá Studená dolina Valley were deposited no later than around 20.5 ka and 15.5 ka, respectively. The timing of these advances is broadly synchronous within the High Tatra Mts. as well as with glacier advances in the Alps, Bavarian/Bohemian Forest and Krkonoše Mts. 10 Be exposure ages obtained from glacially transformed bedrock surfaces range between 20.5 ± 1.7 ka and 10.7 ± 0.3 ka constraining the onset and the final phase of the deglaciation. Surface exposure dating of four rockfall accumulations produced uncertainty-weighted mean ages of 20.2 ± 1.2 ka, 17.0 ± 0.7 ka, 16.5 ± 0.4 ka and 15.6 ± 0.7 ka. These ages indicate that activation of rock-slope failures occurred under paraglacial conditions within a few centuries up to 1400 years after the formation of re-advance moraines. [ABSTRACT FROM AUTHOR]

The timing of mountain glacier fluctuations is poorly constrained in some parts of Greenland during the Late Holocene. We present 31 10Be cosmic‐ray exposure ages (CRE) of boulders collected from three mountain glacier moraines located in the Tasilap valley, in southeastern Greenland, and 10 10Be CRE ages from one mountain glacier in the Isortup valley, in southern Greenland. For the first time in these areas, mountain glacier fluctuations are documented from moraine CRE for the Late Holocene period. Several glacier advances during the Late Holocene are revealed with exposure ages ranging from 3.90±0.26 to 0.4±0.04 ka. Moraines of three of the four glaciers investigated, dated to 3.75±0.13 ka (n = 3), 3.3±0.19 ka (n = 2) and 2.87±0.13 ka (n = 3), show a common timing of the largest glacier expansion during the Late Holocene. Evidence of at least one individual moraine deposited at ~1.2 ka was found on all glaciers. Finally, the most recent period of glacial advance during the Late Holocene is documented by one glacier in each valley at ~0.66–0.70 ka. The maximum glacier extent at ~3 ka differs from the Late Holocene glacier maximum extent usually reported during the Little Ice Age in east Greenland based on moraine dating and lake sediments. We suggest that the combination of a stronger East Greenland Current and a weaker Irminger Current, potentially associated with increased sea‐ice concentration, superimposed on the long‐term decrease in summer insolation during the Late Holocene could be responsible for this large glacial advance at ~3 ka in southern and southeastern Greenland. [ABSTRACT FROM AUTHOR]

Abstract: A glacial chronology based on in situ-produced 10Be surface exposure dating of moraines in the Bohemian Forest (Central Europe) was established. Eleven exposure ages obtained for moraine boulders in the Prášilské Lake and Laka Lake valleys (Czech Republic) were complemented by 10Be ages from Kleiner Arbersee (Germany) recalculated according to recently calibrated production rates in the Northern Hemisphere. The glacial phases in the Bohemian Forest occurred during the Last Glacial Maximum around 24.1 ± 2.5, 23.6 ± 2.4, 21.8 ± 2.0 and 19.5 ± 2.1 ka. Following phases of local glaciation occurred during the Northern Hemisphere deglaciation period around 16 ka and 14 ka. The last indicated phase may correlate with Older Dryas. The glacial chronology of the Bohemian Forest is in agreement with local glaciation chronologies in the Giant Mts. (Krkonoše Mts.) and the Eastern Alps. [Copyright &y& Elsevier]

Abstract: New Terrestrial Cosmogenic Nuclides (TCN) 10Be ages obtained on glacially polished rocks from the SW Alps (Tinée Valley, France) allow a comparison with ages obtained using similar methods for dating the deglaciation steps after the Last Glacial Maximum on the northern and southern sides of the Alps. The data presented in this study highlight three stages of glacial retreat on the southern flank of the Alps at remarkably similar ages that are 14.9 ± 0.8 10Be ka for the end of Oldest Dryas cold period, 10.9 ± 1.1 10Be ka for the end of Younger Dryas cold period and 8.4 ± 0.9 10Be ka for a late ice retreat stage. Previously published data from the Northern Alps lead also to an age of 15.7 ± 1.0 ka for the Oldest Dryas deglaciation, followed by the Younger Dryas at 11.3 ± 1.0 ka, and a late discrete ice retreat event at 9.7 ± 1.2 ka. The last glacial retreats occur thus simultaneously across the Alps and the deglaciation process was most likely unrelated to variations in latitude or to mountain flank exposition throughout the Alps. This may be ascribed to a relatively rapid climate change. Subsequent mountain slope evolution following the rapid glacier unloading is reflected by landslides and fault reactivation directly following the deglacial period. This temporal coincidence is ascribed to a cause-to-consequence effect of glacial unloading and water infiltration into tectonic and landslide triggering. [Copyright &y& Elsevier]

The aim of this work is to build a new chronology of the Late Pleistocene glacial fluctuations in the Cantal Mountains and on the Cézallier Plateau (western Massif Central, France). The study of glacial landform-sediment assemblages is supported by the production of new exposure ages (n = 48) from (i) forty-three erratic boulders (36Cl and 10Be) spread over twelve glacial landforms, (ii) two ages from polished bedrocks (10Be) and (iii) three ages from depth profiles (10Be and 26Al) in tills. The results indicate that the majority of glacial deposits are attributed to Marine Isotopic Stage 2 (29 to 11 ka). From this dataset, four glacial stadials are discriminated: the Early-Local Last Glacial Maximum at 29–24 ka, (ii) Late-Last Glacial Maximum at 24–20 ka, (iii) a glacial still stand at approximately 17 ka, during a general deglaciation phase between 20 and 16 ka and finally (iv) a cirque stadial localized only in the Cantal Mountains at <16 ka. This new chronology strengthens the chronostratigraphy of the western Massif Central and highlights the sensitivity of the area to atmospheric circulation changes. • Revisions of glacial landform-sediment assemblages define four distinct glacial events. • Glacial fluctuations are dated to the MIS 2 with surface exposure ages using 10Be, 26Al and 36Cl (n = 48). • Two major glacier advances occurred during the Last Glacial Maximum, at 29–24 and 24–20 ka. • The paleoglacier is limited to the Cantal cirques from ~16 ka. • Paleoglacier from the western Massif Central are sensitive to north Atlantic paleoclimatic changes. [ABSTRACT FROM AUTHOR]

Abstract: Located in the foreland of the Western Alps, the Crau Plain was the outlet of the Durance River in the Pleistocene. In order to constrain its geodynamic evolution in terms of chronology and denudation rates, the two main Quaternary deposits of this plain have been studied based on cosmogenic nuclide 10Be concentration measurements along depth profiles. The abandonment of the Miramas and Luquier alluvial surfaces occurred at the beginning of glacial periods, Würm (isotopic stage 4) and Riss (isotopic stage 6), respectively. Discrepancy in denudation rates under similar geomorphological and lithological conditions suggests different denudation processes during glacial and interglacial periods. The denudation rate has been estimated at about 25mmka−1 for the interglacial period and about 60mmka−1 for the glacial period. The abandonment of the Crau Plain as the outlet of the Durance River occurred sometime between 75 and 35ka. [Copyright &y& Elsevier]

Abstract: In this paper, we make an inventory of geomorphic remnants of past glaciations, especially glacial stages that occurred just after the Last Glacial Maximum (LGM). More than 35 terrestrial cosmogenic radionuclide (TCR) ages were obtained, providing new chronological benchmarks for defining the transition between the LGM and the Holocene, thus answering some remaining questions in the southern French Alps (upper Durance catchment). TCR ages fit very well with the scenario defined in other parts of the European Alps: two main generations of post-LGM moraines were identified, highlighting a synchronicity of glacial responses during the Younger Dryas and the Preboreal. Indeed, the first generation we identified corresponds to the Younger Dryas period, while the second generation was shaped during the Preboreal period. They suggest that a relatively thick glacier tongue (300m thick) occupied the upper catchment until the end of the Lateglacial period. The glacier tongue disappeared at the very beginning of the Holocene, before a short glacial re-advance during the Preboreal period. This scenario is linked to a very low equilibrium line altitude (ELA) during the Younger Dryas and the Preboreal: located respectively 340 and 150m below the Little Ice Age (LIA) ELA. Collectively, the results highlight a significant west–east gradient in ELA, probably in relation to westerly and northwesterly winds. Finally, the deglaciation pattern in this area is similar to that of the western and northern Alps, and appears significantly different from the patterns found in the inner and eastern Alps (such as the Ubaye and Maritime Alps patterns). [Copyright &y& Elsevier]

The studied dataset from the Southern Carpathians permitted the quantification of a considerable amount of inherited 10Be in the glacial boulders and bedrock samples in the cirque area. The samples from the glacial phases of largest extension display no signs of significant inheritance, and enabled the establishment of a deglaciation chronology in the southern valleys of the Retezat Mts. The timing of the maximum glacier extent (20.6+0.8/ − 1.3 ka) coincided with the Last Glacial Maximum, which was followed by five deglaciation phases during the Lateglacial having partly overlapping ages due to fast glacier retreat (at 18.4+0.7/ − 1.1 ka; 16.9 ± 0.9 ka, 15.8+0.9/ − 0.6 ka, 15.6+0.8/ − 0.8 ka and 14.4 ± 0.5 ka) but could be distinguished by the position of their terminal moraines. The currently available geochronological data do not support the assumption of any major glacial re-advance after Greenland Stadial 2.1a in the Retezat Mts. Given the lack of independent geochronological data, the amount of inherited cosmogenic nuclides is tentatively estimated by accepting the youngest cosmic ray exposure age(s) as the time of moraine deposition and abandonment by the glacier. The calculated amount of inherited 10Be enables the estimation of a glacial erosion depth of 1.1–1.6 m for the bedrock samples and 1.4–1.8 m for the glacial boulders. The duration of the ice-covered and ice-free periods was adjusted in relation to independent paleoenvironmental and paleoclimatological data. The glacial denudation rate in the cirques was estimated at 19–28 mm/kyr and 24–33 mm/kyr for bedrock and boulders, respectively. The limited glacial erosion in the cirques during the last glaciation is attributed to frozen-bed conditions with no considerable glacial deepening during the more extended glacial phases. Only when warming led to the retreat of the glaciers to their cirques, they become steeper and shift to being warm-based and thus more erosive. However, the limited time spent under these conditions appears to be too short to remove material from the cirque floors in sufficient depth (>3 m) to reset the cosmogenic clock. This suggests that the development of the cirques must have taken place during several subsequent glacial phases, providing an indirect confirmation of repeated Quaternary glaciations in the Retezat Mts. • The most extended glaciation during the LGM • Fast deglaciation between ~16 ka and ~14 ka • Inherited 10Be inventory in boulder and bedrock samples in the cirques • Limited glacial erosion in cirques (1.1–1.8 m) with a rate of 19–33 mm/kyr • Modest erosion in the last glacial cycle indicates repeated Quaternary glaciations. [ABSTRACT FROM AUTHOR]

Fluvial incision is the consequence of landscape readjustment to combined tectonic and climatic processes. In the southwestern Alps (Haute Provence Geopark), deep gorges incised by the Bès River attest of efficient erosional processes at the front of the Alpine mountain range. This catchment stands in a peripheral Alpine position, out of the glaciated domain during the last glacial periods, which makes it suitable to quantify fluvial incision and related erosional processes in a glacier-free environment. In this paper, we combine high resolution 3D topographic mapping and in situ produced cosmogenic 36Cl dating of a mountain gorge (the "Clue de Barles" Gorge). First, the very high-resolution 3D topographic modeling from aerial and drone surveys permits to map the erosion markers on the gorge walls and to accurately determine the topographic shielding factor for Cosmic Ray Exposure (CRE) dating. Secondly, 36Cl CRE age distribution highlights two distinct geomorphic domains along the vertical profile: i) the higher section is characterized by clusters of similar CRE ages, interpreted as related to paraglacial rockfall events; ii) the lower section shows increasing ages with height, which are ascribed to fluvial incision occurring at a rate of 0.15 mm/yr since 25 ka, and of 2 mm/yr since 2 ka. Our results for the Clue de Barles, compared to other sites in the South French Alps highlight that: i) the gorge morphology is the result of the combination of both vertical fluvial incision and lateral gravitational processes, ii) the mean Quaternary fluvial incision rate in the Bès River catchment is at least twice lower than further east in the formerly glaciated Alps. • Bès river fluvial incision rate is 0.15 mm/yr since 25 ka. • Clusters of similar exposure ages are interpreted as postglacial rock fall events. • The gorge is shaped by vertical fluvial incision and lateral gravitational processes. • Bès River Quaternary incision rate is at least twice lower than in the SE Alps. [ABSTRACT FROM AUTHOR]