Maximum extent and readvance dynamics of the Irish Sea Ice Stream and Irish Sea Glacier since the Last Glacial Maximum

Abstract

The BRITICE‐CHRONO Project has generated a suite of recently published radiocarbon ages from deglacial sequences offshore in the Celtic and Irish seas and terrestrial cosmogenic nuclide and optically stimulated luminescence ages from adjacent onshore sites. All published data are integrated here with new geochronological data from Wales in a revised Bayesian analysis that enables reconstruction of ice retreat dynamics across the basin. Patterns and changes in the pace of deglaciation are conditioned more by topographic constraints and internal ice dynamics than by external controls. The data indicate a major but rapid and very short‐lived extensive thin ice advance of the Irish Sea Ice Stream (ISIS) more than 300 km south of St George's Channel to a marine calving margin at the shelf break at 25.5 ka; this may have been preceded by extensive ice accumulation plugging the constriction of St George's Channel. The release event between 25 and 26 ka is interpreted to have stimulated fast ice streaming and diverted ice to the west in the northern Irish Sea into the main axis of the marine ISIS away from terrestrial ice terminating in the English Midlands, a process initiating ice stagnation and the formation of an extensive dead ice landscape in the Midlands.

An Integration of Numerical Modeling and Paleoenvironmental Analysis Reveals the Effects of Embankment Construction on Long‐Term Salt Marsh Accretion

“…Our results agree with the interpretation of Lyons (1997) that sediments are delivered into the estuary mainly by tidal pumping. They further support previous hypotheses that abundant legacy of sediment left during the last glacial cycle (Scourse et al, 2021) and regularly remobilized through the central Irish Sea, often as sediment waves (Van Landeghem et al, 2012), has been the main source of sediment supply to the estuary (Wright et al, 1971). Where Δθ is between 0° and 180° the system is flood dominated (blue arrows), where Δθ is between 180° and 360° the system is ebb dominated (red arrows).…”

“…The central Irish Sea is characterised by waves of mobile sediments that move up to 70 m per year (Van Landeghem et al., 2012). This high amount of mobile sediment has been linked to the legacy of sediments discharged through the melting and retreat of the Irish Sea Glacier (Scourse et al., 2021; Van Landeghem & Chiverrell, 2020) and Wright et al. (1971) suggested that these sediments are the major source of sediment supply to the Ribble estuary.…”

Growth and retreat of the last British–Irish Ice Sheet, 31 000 to 15 000 years ago: the BRITICE‐CHRONO reconstruction

“…2021; Scourse et al . 2021), each documenting ice‐marginal positions, flow geometry and geochronological constraints as the ice margin withdrew. These results on the pacing of ice withdrawal were used to interpret the main controls that drove and modulated ice‐sheet retreat.…”

High-resolution 3D geological modelling of heterogeneity in poorly exposed glacial deposits using sedimentary and glaciotectonic architectural element analysis: a case example from Sellafield in west Cumbria, UK

“…Glaciers emerged once again from the western valleys of the Lake District, particularly Wasdale, to lay down the very stony Holmrook Till. This occurred during the build-up of ice towards the Last Glacial Maximum (LGM), which probably reached its maximum extent between 27 and 24ka (Clark, et al, 2012;Livingstone, et al, 2012;Chiverrell, et al, 2013;Chiverrell, et al, 2018;Scourse, et al, 2021), when the whole region was ice-covered. Scottish ice eventually deflected Lake District ice southwards along the coast, flowing across the valleys of the Ehen, Calder and Lower Wasdale, laying down the Low Wath and Ravenglass tills (Table 1).…”