Reconstructing terrestrial ice sheet retreat dynamics from hummocky topography using multiscale evidence: An example from central Ireland

The research reported here combines high-resolution digital elevation models (DEMs) derived from airborne LiDAR with ground-penetrating radar (GPR) surveys and macro- micro-scale sedimentological analyses to study the geomorphology internal structure composition of ridges mounds within an area hummocky topography in Brosna basin, central Ireland. Our evidence indicates that much consists fragmented mega-scale glacial lineations (MSGLs) indicating a phase accelerated ice flow, overlain by groups small composed subglacially till sediment gravity flow deposits. Subtle differences ridge morphology indicate they may be multi-genetic formed both ice-marginally as moraines ribbed moraine. We interpret MSGL-ridge associations subglacial bedform continuum reflecting evolution deforming bed brittle deformation, due changing thermal hydrological conditions at ice-bed interface during sheet retreat. Adjacent glaciofluvial landforms initial en- supra-glacial meltwater drainage, possibly directly related basal thermal/hydrological characteristics formation. Subsequently conduit system evolved, later retreat involved formation ice-marginal ridges. partially preserved landsystem reflects polythermal active temperate marginal zone, rather than stagnating margin previously assumed for this area. work demonstrates usefulness identifying changes deglaciation importance combining multiple strands reconstructing processes landform construction.