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Past sea levels provide important constraints on global ice volumes, rates of tectonic motion, ice-sheet sea-level feedbacks, and the migration of species through time. Beneath formerly glaciated regions, the marine limit, the maximum extent of sea-levels after glacial retreat, provides some of the oldest post-Last Glacial Maximum (LGM) sea-level constraints. However, although the elevations of marine limits are plentiful, they often remain undated. In this study, we provide new age and elevation constraints on the late Pleistocene relative sea-level (RSL) history at 12 sites along the eastern flanks of the former Minch Ice Stream (MnIS) of northwest Scotland. Optically stimulated luminescence (OSL) was used to date the highest and presumably oldest preserved RSL indicators immediately after ice-sheet retreat. Although slightly older than earlier estimates, our ages confirm the early deglacial age of ~16.2–19.5 ka for the raised shorelines of northwest Scotland with declining marine limits north of the Isle of Skye from 26.2 ± 4.8 m at Ardaneaskan to 12.8 ± 4.8 m elevation at Achiltibuie, the latter of which lies inside the moraines of the Wester Ross Readvance. Our new OSL ages suggest deglaciation of the MnIS may have been slightly earlier than previously thought, although our large error bars highlight the need for additional age constraints. Our new RSL data provide important constraints for Glacial Isostatic Adjustment (GIA) models for Scotland and shed light on the behavior of the former MnIS, thought to be susceptible to marine ice-sheet instability. 

Sea-level changes in polar environments are important for understanding the timing and magnitude of past ice-sheet changes. Most of the few records of such past sea-level changes in Antarctica are those derived from raised beach ridges. Many studies using raised beach ridges to reconstruct past sea levels across Antarctica commonly assume that they only record falling sea levels. However, their internal architecture may contain a record of other oscillations in relative sea-level (RSL) change. In this study, we examine the internal architecture of a well-developed set of raised beach ridges on Livingston Island of the Antarctic Peninsula using 10+ km of ground penetrating radar (GPR). Recalibrated published radiocarbon ages are used in combination with new optically stimulated luminescence (OSL) ages to compare beach morphology and stratigraphy to the glacial history of the region. Within this flight of raised beach ridges, evidence was found for both regressive and transgressive depositional patterns marked by progradational seaward dipping facies deposited during periods of RSL fall followed by erosion and deposition of landward dipping overwash and aggrading beds during interpreted periods of RSL rise. This succession is routinely located over a notch in the bedrock interpreted to represent a wave-cut feature. The ages of raised beach ridges underlain by wave-cut notches and composed of landward-dipping strata correlate with known Holocene ice advances at <500, ~2000, and ~5000 cal yrs BP. We propose that these transgressive phases are the result of glacial-isostatic adjustment (GIA). This GIA hypothesis further supports recent assertions of a much more dynamic RSL history for Antarctic coastlines, which may contaminate the Last Glacial Maximum RSL signal across Antarctica. 

ABSTRACT Raised shorelines provide important constraints on past sea levels, glacial isostatic adjustment (GIA), and rates and directions of vertical crustal motion. Although most raised shorelines across NW Scotland relate to post‐Last Glacial Maximum (LGM) glacial‐isostatic rebound, many undated shorelines lie above the marine limit established from isolation basins. Here, we present new optically stimulated luminescence (OSL) ages for a raised marine terrace at an elevation of 28 m in Slaggan Bay of NW Scotland. Four OSL ages suggest the feature is pre‐LGM, likely Marine Isotope Stage (MIS) 3. Global mean sea levels (GMSL) during MIS 3 are thought to have been ~40–60 m below present across most of the globe. We use a pair of GIA models to determine what ice sheet and sea‐level scenarios might provide an explanation for these anomalously high sea levels during MIS 3. Our results suggest that in the absence of tectonic activity, such high MIS 3 shorelines across NW Scotland require a MIS 4 ice sheet in Scotland, with postglacial rebound of the crustal depression following its demise during MIS 3 responsible for the elevated shoreline features at that time. 

Global sea levels during the last interglacial (LIG), 129,000–116,000 years ago, may have reached as much as 5–10 m higher than present. However, the elevation of the LIG highstand varies locally due to tectonics, subsidence, steric effects, and glacial isostatic adjustment (GIA). The variability brought upon by GIA can be used to constrain the past distribution of ice sheets including the source of higher sea levels during the LIG. In spite of its importance for fingerprinting the source of additional meltwater at the LIG, little is known about the elevation of LIG sea levels across Antarctica. In this study we review the geologic constraints on the elevation of the LIG highstand across Antarctica. We find that although several Late Pleistocene sea-level constraints are available across the continent very few of them provide definitive LIG ages. Arguably the most probable LIG sea-level indicators come from East Antarctica but most of them have age constraints approaching the limits of radiocarbon dating (>~45 ka) with many likely dating to Marine Isotope Stage 3, not the LIG. For West Antarctica, Late Pleistocene sea level constraints are confined to a few poorly or completely undated possible examples from the Antarctic Peninsula. Our review suggests that much more work is needed on constraining the elevation of the LIG highstand across Antarctica. 

Abstract In order to reconstruct past environmental conditions along the north-eastern Antarctic Peninsula, we documented changes in grain size, grain roundness, onlap as seen in ground-penetrating radar reflection profiles and ice-rafted debris on a set of 36 raised beaches developed over the last ~7.7 ± 0.9 ka on Joinville Island. The most pronounced changes in beach character occur at ~2.7–3.0 ka. At this time, there appears to have been a reintroduction of less rounded material, the development of stratification within individual beach ridges, an introduction of seaweed and limpets to the beach deposits, a change in clast provenance (although slightly earlier than the change in cobble roundness) and a shallowing of the overall beach plain slope. Prolonged cooling associated with the Neoglacial period may have contributed to these changes, as the readvance of glaciers could have changed the provenance of the beach deposits and introduced more material, leading to the change in roundness of the beach cobbles and the overall slope of the beach plain. This study suggests that late Holocene environmental change left a measurable impact on the coastal zone of Antarctica. 

The development and application of luminescence dating and dosimetry techniques have grown exponentially in the last several decades. Luminescence methods provide age control for a broad range of geological and archaeological contexts and can characterize mineral and glass properties linked to geologic origin, Earth-surface processes, and past exposure to light, heat, and ionizing radiation. The applicable age range for luminescence methods spans the last 500,000 years or more, which covers the period of modern human evolution, and provides context for rates and magnitudes of geological processes, hazards, and climate change. Given the growth in applications and publications of luminescence data, there is a need for unified, community-driven guidance regarding the publication and interpretation of luminescence results. This paper presents a guide to the essential information necessary for publishing and archiving luminescence ages as well as supporting data that is transportable and expandable for different research objectives and publication outlets. We outline the information needed for the interpretation of luminescence data sets, including data associated with equivalent dose, dose rate, age models, and stratigraphic context. A brief review of the fundamentals of luminescence techniques and applications, including guidance on sample collection and insight into laboratory processing and analysis steps, is presented to provide context for publishing and data archiving.