Glacial Geomorphology of southern Alberta, Canada

Abstract

During deglaciation from the Last Glacial Maximum three terrestrial ice streams within the south western sector of the Laurentide Ice Sheet competed and coalesced in southern Alberta; the High Plains Ice Stream (HPIS), Central Alberta Ice Stream (CAIS) and the east lobe. The ice streams are characterised by smoothed corridors along which lie lineations that identify multiple flow events, transverse ridges of thrust and push origin, esker networks and large sequences of parallel and transverse meltwater channels. The CAIS and HPIS were dynamic and transitory in nature creating a ‘time-transgressive’ imprint.
The CAIS terminated within southern Alberta creating a wealth of landforms composed of controlled, hummocky, push and thrust block moraines, along with doughnut hummocks, ice walled lake plains, recessional meltwater, tunnel and large spillway channels. The CAIS margin is interpreted to have been polythermal in nature, creating a continuum of landforms that is dominated by active marginal recession.
The methodologies used were placed within an overarching ‘scale approach’, whereby the research initially focused on a small, regional scale and gradually moved to large scale, local investigations. Firstly, Shuttle Radar Topography Mission (SRTM) and Landsat 7 Enhanced Thematic Mapper (Landsat ETM+) data sets were used to map the regional picture. Then, Aerial Photo Investigation (API), ground truthing and sedimentary analyses were employed to provide a detailed, localised focus into the landform sediment assemblages in southern Alberta.