ABSTRACT Mountain glacier moraine sequences and their chronologies allow us to evaluate the timing and climate conditions that underpin changes in the equilibrium line altitudes (ELAs), which can provide valuable information on the paleoclimatology of understudied regions such as tropical East Africa. However, moraine sequences are inherently discontinuous, and the precise climate conditions that they represent can be ambiguous due to the sensitivity of mountain glaciers to temperature, precipitation, and other environmental variables. Here, we used a two-dimensional (2-D) ice-flow and mass-balance model to simulate glacier extents and ELAs in the Rwenzori Mountains in East Africa over the past 31,000 yr (31 k.y.), including the Last Glacial Maximum (LGM), late glacial period, and the Holocene Epoch. We drove the glacier model with two independent, continuous temperature reconstructions to simulate possible glacier length changes through time. Model input paleoclimate values came from branched glycerol dialkyl glycerol tetraether (brGDGT) temperature reconstructions from alpine lakes on Mount Kenya for the last ~31 k.y., and precipitation reconstructions for the LGM came from various East African locations. We then compared the simulated fluctuations with the positions and ages (where known) of the Rwenzori moraines. The simulated glacier extents reached within 1.1 km of the dated LGM moraines in one valley (93% of the full LGM extent) when forced by the brGDGT temperature reconstructions (maximum cooling of 6.1 °C) and a decrease in precipitation (−10% than modern amounts). These simulations suggest that the Rwenzori glaciers required a cooling of at least 6.1 °C to reach the dated LGM moraines. Based on the model output, we predict an age of 12–11 ka for moraines located halfway between the LGM and modern glacier extents. We also predict ice-free conditions in the Rwenzori Mountains for most of the early to middle Holocene, followed by a late Holocene glacier readvance within the last 2000 yr.

ABSTRACT Landscape features that formed when buried ice melted and overlying sediment collapsed are abundant and widespread in the part of Wisconsin’s Northern Highland region glaciated by the Wisconsin Valley Lobe and the western part of the Langlade Lobe. Stagnation and burial of ice of the Wisconsin Valley Lobe are documented by broad tracts of hummocky moraine topography that record the position of the maximum extent of the lobe, and by extensive pitted and collapsed heads-of-outwash and outwash plains deposited during recession. Recession of the Wisconsin Valley Lobe was characterized by episodes of stagnation interspersed with episodes of readvance, documented by small west-east–trending heads-of-outwash. Advances of the western margin of the Langlade Lobe deposited large northwest-southeast–trending heads-of-outwash characterized by extensive areas of pitted and collapsed outwash plains with obscure but recognizable ice-contact faces. Following recession of the Wisconsin Valley and Langlade Lobes, the Ontonagon Lobe advanced out of the Superior Basin and over sediment containing abundant buried ice. Permafrost and debris cover combined to delay the melting of buried ice and the formation of the postglacial landscape. Regional correlation of ice-margin positions, combined with geomorphic and stratigraphic relationships, indicates that ice buried in north-central Wisconsin persisted in some places for up to 5000 yr or more following the recession of active ice.

Abstract Former glaciation style is dictated by physiography and ice dynamics and is encoded in glacial landsystem imprints. As a holistic evaluation of sediment–landform associations and their genetic relationships to the processes involved in terrain development, glacial landsystems can facilitate a preliminary prediction of expected subsurface conditions using depositional surface morphology and wider physiographic setting. This chapter provides exemplars representative of the widely variable glacial depositional environments of the British Isles. The glacial deposits of the British Isles are viewed in terms of the dominant landsystems in the Quaternary sediment–landform record and can be grouped under four categories: (1) ice-sheet-related deposits and (2) upland (hard bedrock) glacial deposits, organized according to subglacial footprints, ice-marginal complexes and supraglacial assemblages; (3) glaciofluvial sediment–landforms, organized according to whether they are ice-contact or proglacial in nature; and (4) subaqueous depositional sequences, related to ice-proximal and ice-distal environments. These glacial landsystems are related to the concept of Quaternary domains in an attempt to translate sediment–landform assemblages into a format that has practicability in engineering geology. In this respect the regional distribution of landsystems resonates to some degree with the classification schemes of ‘glaciogenic subgroups’ and ‘till formation domains’. Beyond the glaciogenic subgroup and domain classifications, landsystems further identify localized complexities and ensure a higher level of detail for site investigations where intensive Quaternary geological assessments have yielded a range of data including geomorphological mapping and outcrop investigations with three-dimensional analyses of borehole archives.