Insights into the behaviour of Northern Hemisphere Pleistocene ice sheets gained from the glacial landform record

Glacial landforms hold a wealth of information about the evolution of large mid-latitude ice sheets during the Quaternary. Streamlined subglacial lineations retain information about past ice flow, subglacial meltwater routes provide information about ice sheet hydrology, and ice-marginal landforms that are eroded or deposited along glacier margins delineate former ice-marginal positions. Thus, the rich landform records found on the now-exposed beds of ephemeral Pleistocene ice sheets provide important archives of palaeo-ice sheet behaviour that can be used to reconstruct the evolution of ice sheets. Over the past few years, I have had the privilege of using high resolution remotely sensed data to study the glacial landform record across three northern Hemispheric Pleistocene ice sheets: the central sector of the Cordilleran Ice Sheet in British Columbia, Canada; the north-west sector of the Laurentide Ice Sheet in the Northwest Territories, Canada; and the Scandinavian Ice Sheet across Norway, Sweden, and Finland.

Glacial landforms are presented from each of these ice sheets, with a particular focus on ice-marginal landforms, which are important indicators of ice extent, retreat pattern and the terminal environment. The character, distribution and diversity of these landforms is investigated and reveals both similarities and differences in ice marginal settings and dynamics as well as the thermal regime of the former ice sheets. There are similarities between the mountainous regions on the bed of the Cordilleran and Scandinavian ice sheets, both of which were particularly important for ice sheet inception and during the demise, and there are similarities in the distribution of hummocky moraines in the polar regions of the Laurentide and Scandinavian ice sheets (above 60°N). Differences in the ice-marginal landform record are also considered and may arise due to variations in large-scale ice sheet dynamics with the three ice sheet sectors varying in terms of ice volume, timing of retreat, influence of marine or lacustrine terminating margins, and the dynamics of their coalescence with and splitting from adjacent ice sheets.