Vincennes Bay provides a unique opportunity to understand the role of bed topography on modulating deglaciation in East Antarctica. Here, one of the deepest troughs on the margin (Vanderford Trough), lies adjacent to a terrestrially grounded, independent ice dome (Law Dome). Thus, we contrast the deglacial history of these systems and provide insights into future ice loss in parts of the continent underlain by large subglacial basins. We use multibeam bathymetry to map the ice retreat of these systems and cosmogenic nuclide dating onshore, to constrain timing. Bedforms suggest at least two phases of retreat across the continental shelf, separated by a large mid-shelf ridge. Seaward of the ridge, bedforms evidence ice sheet expansion to the continental shelf break. Landward of the ridge distinct bedforms, combined with synchronous exposure of the Windmill Islands and Snyder Rocks similar to 10 ka, are consistent with a Marine Ice Sheet Instability style retreat into the overdeepened troughs. This timing evidences a distinct difference in deglacial histories in East Antarctica, with regions east of 60 degrees E stabilising several thousand years earlier than to the west. We explore drivers of this divergence, including the potential for continental shelf geometry to limit warm water incursion to overdeepened grounding lines. Lastly, a gap in exposure age distribution and the reworking of marine material into modern day shear moraines suggest the western margin of Law Dome was retreated further than present similar to 5.7 to 2.3 ka, with re-advance potentially driven by a strengthening of easterly winds after similar to 4 ka.

The Southern Alps of New Zealand, as one of few mid-latitudinal mountain ranges in the Southern Hemisphere, are considered a key site for investigating Holocene glacier chronologies. A multi-proxy approach utilising 10Be cosmogenic radionuclide (CRN) and Schmidt-hammer exposure-age dating (SHD) was applied combined with rigorous geomorphological assessment and mapping. Glaciers in the eastern part of Aoraki/Mt.Cook National Park, Arrowsmith Range, and Liebig Range were investigated. They represent various morphological types and sub-regions, the latter characterised by specific climatic environments regarding precipitation subject to their distance to the Main Divide. Surface-exposure ages presented for moraines on Holocene glacier forelands are derived from 10Be CRN dating (53 samples) and SHD (42,000 tested boulders). Previously reported Early Holocene glacial activity at Cameron Glacier was confirmed by new results from Ashburton Glacier and constitutes a sub-regional pattern for the Arrowsmith Range. A significant Mid-Holocene advance at 5390 +/- 100 a (10Be CRN: n = 13) at Classen Glacier is hitherto unreported in the Southern Alps. Evidence for Mid-Holocene glacier activity is generally scarce and despite it potentially being linked to an intensification of westerly airflow it should preliminary be interpreted as an individual signal. Only at a few newly investigated glaciers is evidence for Late Holocene advances pre-dating the 'Little Ice Age' (LIA) detected. The maximum 'LIA' extent is dated to 250 +/- 20 and 260 +/- 10 a at Godley and Murchison Glaciers, respectively. This 'LIA'-maximum during the Mid-18th century CE corresponds to published data from central Aoraki/Mt.Cook National Park. In the Arrowsmith Range morphostratigraphically corresponding moraines exhibit a complex history of successive formation. This results in a considerable spread of surface-exposure ages and suggests an early 'LIA'-maximum with a supposedly pre-'LIA' moraine as a precursor. All investigated glacier forelands are characterised by a high degree of individuality regarding their single landforms and landform assemblage. An influence of excessive supraglacial debris input by mass movement was detected at several locations. Finally, it is argued that alongside spatial differentiation with compilations of Holocene glacier chronologies for the Southern Alps, measures to tackle this 'geomorphological uncertainty' need to be integrated with any future approaches. Despite the new data available the improved Holocene glacier chronology presented can still not be considered representative enough to allow detailed palaeoclimatic analyses.

Glacial dynamics in the Outer Tropics reflects a complex interplay of variations in precipitation and temperature driven by large scale ocean-atmospheric dynamics. Cosmogenic dating of moraines, palaeoglacier reconstruction and comparison to climate proxies adds to our understanding of palaeoglacier dynamics in relation to these forcings and can help assess future changes of tropical glaciers in response to ongoing climatic changes. Here we present 12 cosmogenic Be-10 exposure ages from three moraines of the Mullucocha Valley in the previously unresearched Cordillera Pariacaca, Peru. These moraines tightly constrain three phases of glaciation in the central Peruvian Andes at 28.0 ka, 15.5 ka and 11.6 ka, attributed to the Last Local Glacial Maximum, Older Dryas and Late Pleistocene-Early Holocene transition, respectively. They add new evidence for the synchronous behaviour of Central Peruvian glaciers relative to the wider Outer Tropics, from the Lateglacial to Early Holocene. Following comparison with regional moraine chronologies, we suggest an early Last Local Glacial Maximum (LLGM) in Central Peru which occurred prior to the global LGM. A two-phase glacial maximum in the Outer Tropics at 28 ka and similar to 22 ka is hypothesised. An undated moraine nested inside the LLGM moraine in the Mullucocha Valley is theorised to be representative of the younger 22 ka LLGM phase, closer to the timing of global LGM. The 15.5 ka moraine adds to the growing evidence of stabilisation during the Older Dryas, when cold northern hemisphere conditions enhanced precipitation in the Outer Tropics. The 11.6 ka moraine could be connected to the very Early Holocene or late Younger Dryas and is exemplary of a time of widespread moraine formation across the Outer Tropics. It represents a period of glacier stillstand within the wider post-LGM retreat, reflecting periods of cooler, wetter conditions within the overall warming trend. This study provides new insights into the glacial and climate history of the central Peruvian Andes and highlights the need for updated palaeoclimate reconstruction methods.

Much has improved about the glacial history of the British-Irish Ice Sheet (BIIS) during the Last Glacial Cycle (MIS 5d) thanks to rich data sets generated by the BRITICE Project. However, the south-west sector, between the Celtic Sea and Bristol Channel, is challenging because it is largely secured by marine evidence. However, a glacial landscape, preserved on the granitic island of Lundy, exhibits clear evidence of glacial over-printing with remnant transported glacial boulders, glacially-eroded bedrock surfaces, ice scoured tor stumps and erratic gravels. Lundy marks the intersection of ice flow across the eastern boundary of the Celtic Sea and southern extent of the Welsh Ice Cap at the Bristol Channel. The Celtic Sea transported one of the largest BIIS ice streams and thus has significant implications for understanding rapid deglaciation of large ice-sheets. Together with the Isles of Scilly, further south by ~125 km, both locations are strategically placed to pin down the southern extent of the history of the BIIS and answer the question – when during the Last Glacial Cycle did the BIIS overtop Lundy and if so, did it extend up through the Bristol Channel during the global LGM 27-23 ka yrs ago. Previous exposure ages ranging from 30-50 kyrs, from Lundy (Rolfe, 2012), notably on bedrock, point to a pre-MIS 3 glaciation (most likely MIS 4) ruling out the conclusion that LGM ice reached Lundy. Given that there is strong evidence (OSL and 10Be dating) for Scilly to have been glaciated during the LGM (Smedley et al 2017), which is also supported by BIIS modelling, debate surrounds assigning Lundy 10Be data to true exposure ages (Carr, 2017). The relatively large age spread possibly resulting from cosmogenic inheritance/erosional irregularities and pegmatite/beryl presence in Lundy granite (Mclintock, 1912) may complicate the interpretation of the exposure ages. We have re-visited Lundy and collected 11 new samples comprising erratic boulders perched on polished bedrock, tor stumps and tops. The tor stumps (tops) would have been the least (most) persistent to preservation of inherited nuclides resetting . The new10Be exposure ages when compared to bedrock ages from Rolfe (2012) should confirm whether the timing of BIIS retreat at Lundy was before or during the LGM. Two OSL samples from cover sands over gravel will provide independent age control.An interesting aspect of Lundy granite is the presence of beryl, topaz and other insoluble minerals (ie tourmaline). This required considerable care to quantify the intrinsic 9Be concentration. For example, in 3 quartz samples there was sufficient native 9Be to warrant zero addition of 9Be carrier. Not including a native 9Be contribution would underestimate exposure ages. However, the leaching of meteoric 10Be from these insoluble minerals during quartz dissolution is more of a concern and would result in over estimating exposure ages (Corbett, 2023). The new ages and impact of Lundy granite chemistry for cosmogenic dating will be represented.Rolfe, QSR, v43, 2012Carr, Proc. Geol. Assoc., v128, 2017Mclintock, Mineral. Magazine, v16, 1912Smedley, JQS, v32, 2017Corbett, QG, v73, 2023

Shore platforms along rock coasts have long puzzled geomorphologists regarding their age and formative processes. This study combines cosmogenic nuclide (CN) dating and micro-erosion meter (MEM) measurements to investigate the evolution of microtidal shore platforms on the Otway Coast of Victoria, Australia. CN concentrations across four platforms reveal significantly high values (up to 123,831 atoms g−1) compared to previous studies, indicating formation predating the Holocene. Cross-shore CN distribution shows peak concentrations at the seaward edge, decreasing landward. MEM data collected over 44 years demonstrate active contemporary erosion, with downwearing rates closely related to elevation and tidal inundation frequency. Numerical modelling of both CN concentrations and MEM-calculated downwearing rates suggest platform initiation during at least the Last Interglacial period, with subsequent modification during the Holocene. The results indicate that platform width is morphologically-inherited from past higher sea levels, while the contemporary cross-shore morphology results from Holocene downwearing processes. This study provides evidence for long-term morphological inheritance in shore platform evolution, challenging the notion of purely Holocene formation in resistant lithologies. The findings highlight the complex interplay between inherited landforms and ongoing erosive processes in shaping rock coast geomorphology, contributing to our understanding of coastal landscape evolution over glacial-interglacial timescales.

Sediment dynamics and rates of landscape denudation in dryland regions are difficult to quantify due to long residence times of sediment on hillslopes and floodplains, often exceeding millions of years. Such extended durations complicate the interpretation of single cosmogenic nuclide analyses. This study applies paired Be-10 and Al-26 measurements in detrital samples to constrain basin-wide denudation rates and sediment fluxes within the semi-arid Upper Fortescue catchment, located in the Pilbara, northwestern Australia. Morphometric data, lithology and dual cosmogenic nuclide concentrations are integrated to quantify long-term basin-wide denudation rates and evaluate first-order controls on sediment production, transport and catchment evolution. A stepwise series of corrections were conducted for topographic shielding, lithology and apparent sediment burial. Corrected nuclide concentrations yield basin denudation rates in the Upper Fortescue catchment that range from 0.83 to 3.02 m/Ma. These values are comparable to channel bedrock rates (2.5 +/- 0.8 m/Ma; n = 4) and moderately higher than estimates from mesa summits and alluvial fan surfaces (0.8 +/- 0.6 m/Ma; n = 13) previously derived from Mn-53 measurements. Nine of eleven detrital samples exhibit Al-26/Be-10 ratios between 4.7 and 5.8, lower than the nominal production ratio of 6.75, indicating that sediments must have experienced a complex exposure history. Two conceptual scenarios are proposed to explain these ratios: (a) extended burial in colluvium or channel sediments lasting several hundred thousand years, and/or (b) complex exposure as a result of production rate attenuation at depth in slowly eroding (<5 m/Ma) bedrock, when sub-surface rock become exposed, probably through spalling of large meter-sized blocks from vertical cliff surfaces along escarpments and gorges, ubiquitous in the region. In scenario (b), most of our data are explained by materials being sourced from the average depth of 0.5 to 1 m. However, progressive downstream transport of channel sediments increases the likelihood of storage at shallow depth for a prolonged period in riverbanks, colluvium and floodplains. Field evidence combined with cosmogenic nuclide data supports a hybrid model involving both scenarios. These findings demonstrate the effectiveness of dual-nuclide analysis in quantifying long-term catchment-scale denudation and provide new insights into sediment source-to-sink processes in arid landscapes.

The Paleoproterozoic Warton and Wunaamin Miliwundi Sandstones in the Kimberley Basin of NW Australia contain an abundance of rock shelters hosting a striking succession of rock paintings of immense cultural and archaeological significance. The evolution of these shelters has not previously been studied in detail, yet provides the ultimate control on the long-term survival of rock art within them. The rock shelters develop initially on near-vertical sides of remnant sandstone blocks on an etched landscape exhumed from a formerly pervasive deep lateritic weathering zone of probable Neogene age. The two nearly flat-lying sandstone formations are highly cemented orthoquartzites characterized by brittle behaviour revealed in a landscape-scale pattern of etched joint planes and small strike-ridge scarps along which shelters develop. Consistent features of these rock shelters reflect their mode of origin and subsequent evolution through a life cycle lasting tens of thousands of years or more. These include horizontal bedding-plane ceilings and fractured back walls cutting through sandstone beds, which host most of the rock paintings. Fractures mostly dip back towards the deepest part of the shelter near the floor. The first stage in shelter development involves undermining by crushing of a relatively thin incompetent bed to form a recessed bedding cave in the absence of normal erosional agencies. Overlying massive sandstone beds are left unsupported and progressively collapse in one or more intact slab falls. Further falls lead to gradual enlargement and a rocky floor piled with fallen slabs. The geometry of the fractured back walls suggests that both tensile and shear failure are involved in shelter growth in a series of mass wasting events. Subsequent spallation and dilational flaking on sandstone surfaces on the lowermost sandstone faces modify the shelter walls. Eventually, the shelter may be destroyed by toppling forward due to continued undermining at the base.

This study investigates surface weathering and sediment preservation at Table Mountain, a high‐elevation, hyperarid, polar landscape in the Transantarctic Mountains. We report cosmogenic nuclide concentrations ( 10 Be and 26 Al) in quartz from bedrock surfaces, erratic boulder lag, and cobbles embedded within Sirius Group sediments to quantify erosion rates. In situ 10 Be and 26 Al depth profiles from a 2.95 m permafrost core in the Sirius Group further constrain surface erosion rates and elucidate landscape stability. Measured 10 Be and 26 Al concentrations from two sandstone bedrock surfaces adjacent to Sirius Group sediments give erosion rates of 0.18–0.28 m/Myr. An erratic sandstone boulder within the lag above the Sirius Group yields erosion rates of ∼0.42 ± 0.03 m/Myr, whereas two cobbles embedded within the Sirius Group yield higher rates of 0.81–1.12 m/Myr. Depth profiles of in situ 10 Be and 26 Al indicate no vertical mixing of Sirius Group permafrost since deposition. Depth profile models are best explained by erosion rates of 0.53 +0.13 / −0.12 m/Myr, and an exposure age of 0.78 +0.06 / −0.08 Ma. We view the model “age” to represent the ∼0.8‐million‐year time‐scale for surface lowering equivalent to one attenuation length of cosmic ray production to achieve steady‐state conditions. Continual exhumation of embedded clasts from within the Sirius Group results in an accumulation of clasts forming the observed erosional lag deposit covering the landscape. Our erosion rates of the Sirius Group surface based on in situ 10 Be and 26 Al depth profiles are an order‐of‐magnitude larger than those based on meteoric 10 Be infiltration and further clarification is required.

In Ireland, the Nahanagan Stadial (NS) was characterised by cirque glacier, plateau icefield and mountain ice cap expansion and is named after the cirque glacier type-site of Lough Nahanagan in the Wicklow Mountains. This period is broadly equivalent to the Younger Dryas Stadial and Greenland Stadial-1 (GS-1: similar to 12.9-11.7 ka). Here, we provide the first evaluation of the full extent of NS glaciation in the Wicklow Mountains by combining solar radiation modelling, mapping of glacial geomorphology, Be-10 and Al-26 cosmogenic surface exposure dating, 3D glacier reconstructions and analysis of snowblow and avalanching potential. We identify seven sites that hosted cirque glaciers at this time. Glacier extent was very restricted, with most glaciers only partially filling their cirques. Equilibrium line altitudes (ELAs) ranged from 470 +/- 5 m a.s.l. (Lough Nahanagan) to 721 +/- 5 m a.s.l. (Lough Cleevaun), with an average ELA of 599 m a.s.l. Higher snowblow and avalanching contributions at sites with lower ELAs demonstrate local topoclimatic influence on glacier growth and preservation alongside regional climate. The Wicklow Mountains provides a good example of marginal cirque glaciation during GS-1 and the importance of local topography and microclimate for sustaining glaciers in some mountain areas of Britain and Ireland. (c) 2025 The Authors Journal of Quaternary Science Published by John Wiley & Sons Ltd.

Meteoric-Be-10 has become a popular proxy for assessing glacial environments and processes around Antarctica, such as meltwater discharge or ice shelf environments. Despite applications in recent paleostudies, little testing of the mechanisms driving the deposition of Be-isotopes into marine sediments has been conducted. We used chemical leach procedures to sequentially or partially extract Be-10 and Be-9 from bulk sediments to assess the possible sources and depositional processes affecting them. Additionally, we leached the reactive phase of five different grainsize splits to determine whether Be-10/Be-9 ratios normalise for grainsize effects acting upon the Be-10 concentration. Reactive Be-isotopes are primarily situated in the oxide phases of sediments, with the amorphous oxide (Am-Ox) phases consisting of much higher Be-10/Be-9 ratios (similar to 7-10 x 10(-8)) than the crystalline oxides (similar to 1-3 x 10(-8); X-Ox), indicating that the Am-Ox phase better represents authigenic oxide production and a circumpolar deep water source, which is contrary to most of the current literature. Published leach procedures targeting the reactive phase of sediment consist of ratios in between the Am-Ox and X-Ox phases (similar to 3-7 x 10(-8)), indicating that they target both phases to some degree. The fractionation of Be-isotopes in Antarctic sediment samples shows that circumpolar deep water is the primary source of Be-10, and that the "reactive" signatures from different leach steps targeting the reactive phase are not the same.

We present 35 new burial ages (27 sites) based on 26Al / 10Be ratios of terrestrial cosmogenic radionuclides measured in clasts and sediments deep within 12 caves in the southern Massif Central, France. Our results, together with previously published burial ages, verify that cave morphogenesis has been continuously active in this region for at least the past ∼ 6 Myr. Combining sample burial ages with their associated cave elevation above the modern stream bed gives a mean regional incision rate of 88 ± 5 m Ma−1 for the Grands Causses area. South of the Cevennes Fault Zone bordering the Grands Causses, the incision rate is 43 ± 5 m Ma−1, suggesting that this difference might be accommodated by the fault zone. Sediment burial ages from caves which are not located on river valley flanks or cliff walls are surprisingly too young compared to their expected ages when calculated using this regional average river incision rate. This suggests that the classical epigenic speleogenesis model that presumes a direct correlation between cave level development and regional base level lowering does not apply for the study area. Therefore, we propose that regional speleogenesis is mainly controlled by the removal of ghost rocks by headward erosion from river canyons to central parts of the plateaus, emptying incipient primokarst passages to create cave systems. Our results suggest a continuum process from hypogene primokarst composed of passages filled with ghost rock to one of epigene karst dynamics emptying these passages and creating cave networks. We propose that these processes are the major mechanism in the southern Massif Central that initiates speleogenesis and controls the geometry of the networks. In this region, tiered karst cannot be associated with the pace of incision of the major rivers but must be explained by former ghost rock (or hypogene) processes.

Beryllium-10 (10Be) is proposed to be a potential proxy for investigating ice shelf presence and absence, or meltwater discharge in coastal polar environments. However, the sources and distribution of atmospherically produced meteoric-10Be in the Antarctic marine realm are yet to be fully characterized. We present a dataset of 9Be and 10Be concentrations, and 10Be/9Be ratios in seafloor surface sediments from the Antarctic continental shelf to assess the sources and processes contributing Be-isotopes to ice-sheet proximal marine settings. We show that upwelling waters (e.g. Circumpolar Deep Water) are a significant source of 10Be to continental shelf sediments. This limits the use of 10Be/9Be as a proxy for ice shelf environment or meltwater discharge, but instead provides a potential proxy for reconstructing Circumpolar Deep Water incursions onto Antarctic continental shelves.

Deciphering the global and local drivers of glacial retreat in the tropical Andes in the Late Quaternary is key to understanding how future climate scenarios will affect these glaciers. In Peru, glaciers have high socioeconomic and cultural value, supplying drinking water, hydroelectric power and irrigation. Pariacacá and Huaytapallana mountain ranges (~11.5 ºS), provide meltwater to Lima and Huancayo. Glaciers in Pariacacá, in the western Andes, and Huaytapallana, in the eastern Andes, have experienced a 55% and 56% shrinkage in surface since the 1970s, respectively. No chronologies, however, exist for their extensive moraine sequences which provide clues to the dynamics under various climate forcing scenarios. These could help put present-day and future climate scenarios into context of contemporary change and be used as a test for models aiming to project the response of mountain glaciers to ongoing climate change. Using Terrestrial Cosmogenic surface exposure dating, this study provides the first glacial geochronology for these mountain ranges based on 32 10Be exposure ages of eight moraines. The Peruvian climate and glacial dynamics have been linked to variations in sea surface temperatures, the displacement of Intertropical Convergence Zone, and intensity of the South American Summer Monsoon. The climate is also modulated by the Andean Mountain chain, which acts as a topographical barrier causing a rain shadow on its western flank. This barrier affects the relative influence of these factors on the different sides of the Andes. This study aims to help constrain the ocean and atmospheric controls on past glacier mass balance in Peru, how the controls differed between the Eastern and Western Andes and how they have developed over the late Quaternary. Initial results from Pariacacá indicate a local glacial maximum at 32.6 ± 3ka, around 10kyrs earlier than the global LGM. Following this early glacial maximum, ice appears to have continuously retreated until the Older Dryas. A lateral moraine, dated to 15.9± 0.8ka suggests glacier stabilisation or advancement, under wetter conditions during Heinrich Stadial 1 as the Northern hemisphere cooled causing a southern displacement of the ITCZ. This indicates linkages between glacier retreat in the western Andes and Atlantic SSTs in the past. Following the Older Dryas stillstand the glacier retreated as the climate warmed and dried into the Holocene. A cluster of moraines dated to the Early Holocene (11.4 ± 0.6ka) further adds to the growing evidence that the overall warming trend was interrupted by short intervals of either colder or wetter conditions. Similar early Holocene stillstands are recorded in Huaytapallana at 11.4 ± 0.6ka and 10.9 ± 0.6ka. Both mountain ranges show geomorphological evidence of a Little Ice Age stillstand or advance. At Huaytapallana, initial data suggests this occurred 176 ± 13 years before 2022 during colder and wetter conditions. Analysis of the exposure ages in comparison to palaeoclimate, along with palaeoglacier and palaeoclimate reconstructions will be presented.

While Pleistocene glaciation was extensive in the Atlas Mountains, there are no glaciers today in Morocco, although snowpack usually survives the year in some niche settings. Numerous sites associated with late-lying snow contain niche glacier moraines and pronival ramparts, often with little or no soil development indicating recent formation. The climate history of Morocco makes the Little Ice Age the prime candidate for any Holocene expansion of snowpack and niche glaciers. While multicentennial cool and wet episodes did occur in the Early and Middle Holocene, overall climate was warmer and unfavourable for sustained snowpack and glacier development, although the implications for snowpack and glacier development in this interval are not yet well known. Fluctuations in snow cover and its persistence in the Atlas Mountains have not only important geomorphological implications but are of vital hydrological and socioeconomic significance. Snow is a strategic resource in Morocco with the Atlas Mountains, providing a sustained supply of water to the neighbouring lowlands through snowmelt through the spring and summer months. Climate change is likely to reduce snow cover duration in the Atlas Mountains. Climate is becoming warmer and drier, which also has the potential to increase atmospheric dust flux. Dust cover increases ablation rates on snow reducing the duration of snow cover further. While niche snowpatches appear to be decoupled from regional climate, exhibiting remarkable resilience, their future is in doubt.

The University of Wollongong (UOW) cosmogenic Be-10 and Al-26 sample preparation laboratory has been in operation since the start of 2017. As primarily a feeder laboratory to ANSTO' s Centre for Accelerator Science, our sample preparation procedures have been optimised with consideration to the setup of ANSTO' s 6MV SIRIUS accelerator, and aim to achieve a balance between sample throughput as well as Be and Al target purity. A comparatively small number of samples (n = 68) have also been prepared for measurement at the Australian National University 14UD accelerator. Be-10/Be-9 ratios of procedural blanks measured on SIRIUS have fluctuated over time with the median for the year 2017 being 5.16 x 10(-16 )(IQR = 4.11 x 10(-16) to 7.16 x 10(-16), n = 18), increasing to 1.62 x 10(-15) (IQR = 1.05 x 10(-15) to 2.17 x 10(-15), n = 31) for 2018 and 2019, a period coinciding with elevated boron levels in our samples, and finally decreasing to 1.15 x 10(-15 )(IQR = 8.63 x 10(-16) to 1.60 x 10(-15), n = 34) for 2020 and 2021. In contrast, Al-26/Al-27 ratios of procedural blanks measured on SIRIUS have shown a slight but continuous improvement over time with the median for 2017 of 1.70 x 10(-15) (IQR = 8.19 x 10(-16) to 5.25 x 10(-15), n = 12) decreasing to 1.07 x 10(-15) (IQR = 8.5 x 10(-16) to 1.53 x 10(-15), n = 13) for 2021. Median Be-10/Be-9 relative uncertainty of procedural blanks analysed on SIRIUS is 18 % (IQR = 15 % to 22 %; n = 86) whereas the median Al-26/Al-27 relative uncertainty of procedural blanks is higher at 60 % (IQR = 41 % to 100 %; n = 56), statistic resulting from most blanks yielding low Al-26 counts (median = 2; IQR = 1-4.5). Average (BeO-)-Be-9 output relative to standard is between similar to 70 % - 80 % for samples analysed on SIRIUS (n = 895) and similar to 130 % for samples analysed at ANU (n = 68). Al-27(-) output relative to standard is lower for samples pressed into cathodes at UOW (similar to 60 %, n = 432) and analysed on SIRIUS than for those pressed at ANSTO (similar to 90 %, n = 119). Average Al-27(-) output relative to standard for samples analysed at ANU is similar to 80 % (n = 62). Be-10 and Al-26 measurements of various laboratory intercomparison materials prepared at UOW between 2017 and 2022 yield results in agreement with consensus values confirming that our chemistry procedures are robust and in line with those elsewhere.

Abstract. During the interglacial and interstadials of Marine Isotope Stage 5 (MIS 5e, 5c, 5a), outlet and alpine glaciers in the Dry Valleys region, Antarctica, appear to have advanced in response to increased precipitation from enhanced open ocean conditions in the Ross Sea. We provide further evidence of this antiphase behaviour through retreat of a peripheral lobe of Taylor Glacier in Pearse Valley, a region that was glaciated during MIS 5. We measured cosmogenic 10Be and 26Al in three granite cobbles from thin, patchy drift (Taylor 2 Drift) in Pearse Valley to constrain the timing of retreat of Taylor Glacier. Assuming simple continuous exposure, our minimum, zero erosion, exposure ages suggest Taylor Glacier partially retreated from Pearse Valley no later than 65–74 ka. Timing of retreat after 65 ka and until the Last Glacial Maximum (LGM) when Taylor Glacier was at a minimum position, remains unresolved. The depositional history of permafrost sediments buried below Taylor 2 Drift in Pearse Valley was obtained from 10Be and 26Al depth profiles to ~3 metres in permafrost in proximity to the cobble sampling sites. Depth profile modelling gives a depositional age for near-surface (< 1.65 m) permafrost at Pearse Valley of 180 ka +20/−40 ka, implying deposition of permafrost sediments predate MIS 5 advances of Taylor Glacier. Depth profile modelling of deeper permafrost sediments (> 2.09 m) indicates a depositional age of > 180 ka. The cobble and permafrost ages reveal Taylor Glacier advances during MIS 5 were non-erosive or mildly erosive, preserving the underlying permafrost sediments and peppering boulders and cobbles upon an older, relict surface. Our results are consistent with U/Th ages from central Taylor Valley, and suggest changes in moisture delivery over Taylor Dome during MIS 5e, 5c and 5a appear to be associated with the extent of the Ross Ice Shelf and sea ice in the Ross Sea. At a coastal, lower elevation site in neighbouring Lower Wright Valley, 10Be and 26Al depth profiles from a second permafrost core exhibit near-constant concentrations with depth, and indicate the sediments are either vertically mixed after deposition, or are sufficiently young and post-depositional nuclide production is negligible relative to inheritance. 26Al/10Be concentration ratios for both depth profiles range between 4.0 and 5.2 and are all lower than the nominal surface production rate ratio of 6.75 indicating that prior to deposition, these sediments experienced a complex exposure-burial history. Assuming a single cycle exposure-burial scenario, the observed 26Al/10Be ratios are equivalent to a total minimum exposure-burial history of ~1.2 Ma. Our new data corroborates antiphase behaviour between outlet and alpine glaciers in the Dry Valleys region and ice extent in the Ross Sea. We suggest a causal relationship of cold-based glacier advance and retreat that is controlled by an increase in moisture availability during retreat of sea ice and perhaps the Ross Ice Shelf, and conversely, a decrease during times of sea ice and Ross Ice Shelf expansion in the Ross Sea.

Uplift of the Tian Shan range modified regional climate during Cenozoic aridification in Central Asia. This study presents facies analyses and Neogene oxygen and carbon isotopic records from magnetostratigraphically dated terrestrial sedimentary sections on the southern side of the intermontane Issyk‐Kul basin in the Kyrgyz Tian Shan and 26 Al/ 10 Be isochron burial ages from the southern and eastern sides of the basin. The δ 18 O and δ 13 C data show a positive ca. 2‰ shift in values between ca. 8 and 7 Ma and a change from a negative to a positive trend. This change is attributed to the upwind growth of the Kyrgyz, Kungey and Trans Ili (Zaili) ranges, which diverted the westerlies, thereby changing the Issyk‐Kul basin from a windward to a leeward position, enhancing aridification and establishing the modern‐day spring and summer precipitation regime within the basin. Two 4 to 5 Ma 26 Al/ 10 Be isochron burial ages constrain the onset of Sharpyl Dak deposition on the eastern side of the basin; southward paleocurrent directions there suggest the eastward growth of the Kungey range in the Pliocene. Increased subsidence on the southern side of the basin and local tectonically induced river system reorganization led to the commencement of lake formation at ca. 5 Ma, followed by a ca. 2 Ma local depositional hiatus. The transition from sandstones of the Chu sedimentary group to conglomerates of the Sharpyl Dak group, marking a change from fluvial‐alluvial deposits to a proximal alluvial fan, is dated at 2.6–2.8 Ma by 26 Al/ 10 Be isochron burial dating on the southern side of the basin, driven either by tectonics or Northern Hemisphere glaciation. This study concludes that the late Miocene–Pliocene northward growth of Tian Shan significantly altered environmental conditions within the range, preventing the moisture‐bearing westerlies from reaching the intermontane Issyk‐Kul basin and promoting lake formation and expansion.

We explore the spatial and temporal variations in denudation rates in the northern Pamir-Tian Shan region using 10Be-derived denudation rates from modern (n = 110) and buried sediment (2.0-2.7 Ma; n = 3), and long-term exhumation rates from published apatite fission track (AFT; n = 705) and apatite (U-Th-Sm)/He (AHe; n = 211) thermochronology. We found moderate correlations between denudation rates and topographic metrics and weak correlations between denudation rates and annual rainfall, highlighting complex linkages among tectonics, climate, and surface processes that vary locally. The 10Be data show a spatial trend of decreasing modern denudation rates from west to east, suggesting that deformation and precipitation control denudation in the northern Pamir and western Tian Shan. Farther east, the denudational response of the landscape to Quaternary glaciations is more pronounced and reflected in our data. Modern Be-10 denudation rates are generally higher than the long-term AFT and AHe exhumation rates across the studied area. In the Kyrgyz Tian Shan, on average, the highest Be-10 denudation rates are recorded in the Terskey range, south of Lake Issyk-Kul. Here, modern denudation rates are higher than 10Be-derived paleo-denudation rates, which are comparable in magnitude with the long-term exhumation rates inferred from AFT and AHe. We propose that denudation in the region, particularly in the Terskey range, remained relatively steady during the Neogene and early Pleistocene. Denudation increased due to glacial-interglacial cycles in the Quaternary, but this occurred after the onset and intensification of the Northern Hemisphere glaciations at 2.7 Ma.

Soil and sediment mixing and associated permafrost processes are not widely studied or understood in the McMurdo Dry Valleys of Antarctica. In this study, we investigate the stability and depositional history of near-surface permafrost sediments to ∼ 3 m depth in the Pearse and lower Wright valleys using measured cosmogenic 10Be and 26Al depth profiles. In Pearse Valley, we estimate a minimum depositional age of ∼ 74 ka for the active layer and paleoactive-layer sediments (< 0.65 m). Combined depth profile modelling of 10Be and 26Al gives a depositional age for near-surface (< 1.65 m) permafrost in Pearse Valley of 180 +20/-40 ka, implying that the deposition of permafrost sediments predates MIS 5 advances of Taylor Glacier. Deeper permafrost sediments (> 2.09 m) in Pearse Valley are thus inferred to have a depositional age of > 180 ka. At a coastal, lower-elevation site in neighbouring lower Wright Valley, 10Be and 26Al depth profiles from a second permafrost core exhibit near-constant concentrations with depth and indicate the sediments are either vertically mixed after deposition or sufficiently young so that post-depositional nuclide production is negligible relative to inheritance. 26Al/10Be concentration ratios for both depth profiles range between 4.0 and 5.2 and are all lower than the nominal surface production rate ratio of 6.75, indicating that prior to deposition, these sediments experienced complex, yet similar, exposure–burial histories. Assuming a single-cycle exposure–burial scenario, the observed 26Al/10Be ratios are equivalent to a total minimum exposure–burial history of ∼ 1.2 Myr. In proximity to the depth profile core site, we measured cosmogenic 10Be and 26Al in three granite cobbles from thin, patchy drift (Taylor 2 Drift) in Pearse Valley to constrain the timing of retreat of Taylor Glacier. Assuming simple continuous exposure, our minimum, zero-erosion exposure ages suggest Taylor Glacier partially retreated from Pearse Valley no later than 65–74 ka. The timing of retreat after 65 ka and until the Last Glacial Maximum (LGM) when Taylor Glacier was at a minimum position remains unresolved. The surface cobble ages and permafrost processes reveal Taylor Glacier advances during MIS 5 were non-erosive or mildly erosive, preserving the underlying permafrost sediments and peppering boulders and cobbles upon an older, relict surface. Our results are consistent with U/Th ages from central Taylor Valley and suggest changes in moisture delivery over Taylor Dome during MIS 5e, 5c, and 5a appear to be associated with the extent of the Ross Ice Shelf and sea ice in the Ross Sea. These data provide further evidence of antiphase behaviour through retreat of a peripheral lobe of Taylor Glacier in Pearse Valley, a region that was glaciated during MIS 5. We suggest a causal relationship of cold-based glacier advance and retreat that is controlled by an increase in moisture availability during retreat of sea ice and perhaps the Ross Ice Shelf, as well as, conversely, a decrease during times of sea ice and Ross Ice Shelf expansion in the Ross Sea.