Reconnaissance Surficial Geology, Rivière Grandin, Northwest Territories, NTS 86-DWednesday, November 21, 2018 - 16:30 to 19:00 Multiplex Gym (DND)
The Rivière Grandin map area is characterized by three glacial terrains identified by different surficial sediments and landforms. In the northeast along and inland from the shores of Hottah Lake, glacial Lake McConnell deltas, beaches and offshore sediments occur between 180-350 m elevation. Farther west, in the Ortona Lake area and westward, terrain near or above 500-600 m elevation is defined by hummocky glaciofluvial sediments, a few morainal ridges, abundant radial meltwater channels, and an absence of ice-flow indicators, which may indicate local cold-based ice regimes. On the eastern edge of these highlands, rare drumlins trend northwestward, perpendicular to the flutings at lower elevations to the north and south. The remaining and most extensive map areas are generally covered by streamlined till with interspersed ridged till (minor moraines). Drumlins, crag-and-tails and drumlinoids record northwestward and southwestward topographically-deflected divergent and convergent ice flows. The area north, west and south of Rome Lake has a greater concentration of ridged till. Late during deglaciation, various minor ice-flow shifts occurred in the southwest map area, indicated by small, superimposed streamlined landforms.