Open AccessSurficial geology, Lac Laporte, Quebec, NTS 23-P southwest
Author(s) -
R C Paulen,
J M Rice,
Martin Ross
Publication year - 2020
Language(s) - English
Resource type - Reports
DOI - 10.4095/314756
Subject(s) - geology , meltwater , subaerial , deglaciation , bedrock , geomorphology , ice stream , ice sheet , paleontology , drumlin , landform , glacial period , physical geography , oceanography , cryosphere , geography , sea ice
The Lac Laporte area is of moderate relief and is characterized by till blankets in the central lowlands and till veneers with large expanses of bedrock outcrops in the west (Doublet Terrane) and east (De Pas Batholith). The region was differentially eroded bythe Laurentide Ice Sheet, largely influenced by the migration of the Ancestral Labrador ice divide. Phases of radial ice flow from the former migrating ice divide imparted discordant erosional-flow landforms and paleo-flow indicators on the landscape. During the latter phase of deglaciation, terrainwest of the Rivière De Pas experienced ice stagnation and ablation, with the westward-retreating ice margin pinned against the bedrock ridge crests. Subaerial meltwaters flowed eastward away from the ice margin, which created a morainal complex of winnowed till and glaciofluvial sediments.These subaerial meltwater channels are juxtaposed with the subglacial meltwater channels that formed parallel to the general north-south-trending bedrock topography.