The identification of glacial dispersal landforms and sedimentary deposits formed by fast-flowing glaciers was important to the earliest recognition of paleo-ice streams of the Laurentide Ice Sheet in the 1970s and 1980s. The spectacular continental-scale Dubawnt dispersal train in northern Canada was one of the first to be identified as the product of a high glacial flow rate. Subsequently, dispersal plumes of Paleozoic carbonate rocks imprinted on Precambrian Canadian Shield terrain in northern Canada were interpreted to be products of ice streams. The geomorphic imprint of ice streams over hard-bed, higher relief areas tends to be less obvious because of thinner till cover and an absence of diagnostic geomorphic features such as shear margin moraines. Despite the relatively thin till cover in some regions of the Canadian Shield, the extremely high concentrations of mineralized (exotic) debris within the till 10s of kilometres down-ice from their sources is quite remarkable. Typically, under normal ice-flow conditions in areas of hard-beds on the Canadian Shield, dispersal trains formed by erosive ice are diluted over relatively short distances (<5 km) down-ice. The long (10s of km) dispersal trains of till with distinct chemical and/or mineralogical compositions, coupled with obvious erosive/depositional corridors of streamlined landforms, provide a means of identifying hard-bedded ice streams elsewhere in northern Canada.🏁

Submitted by azaya - 01/27/2025

The identification of glacial dispersal landforms and sedimentary deposits formed by fast-flowing glaciers was important to the earliest recognition of paleo-ice streams of the Laurentide Ice Sheet in the 1970s and 1980s. The spectacular continental-scale Dubawnt dispersal train in northern Canada was one of the first to be identified as the product of a high glacial flow rate. Subsequently, dispersal plumes of Paleozoic carbonate rocks imprinted on Precambrian Canadian Shield terrain in northern Canada were interpreted to be products of ice streams. The geomorphic imprint of ice streams over hard-bed, higher relief areas tends to be less obvious because of thinner till cover and an absence of diagnostic geomorphic features such as shear margin moraines. Despite the relatively thin till cover in some regions of the Canadian Shield, the extremely high concentrations of mineralized (exotic) debris within the till 10s of kilometres down-ice from their sources is quite remarkable. Typically, under normal ice-flow conditions in areas of hard-beds on the Canadian Shield, dispersal trains formed by erosive ice are diluted over relatively short distances (<5 km) down-ice. The long (10s of km) dispersal trains of till with distinct chemical and/or mineralogical compositions, coupled with obvious erosive/depositional corridors of streamlined landforms, provide a means of identifying hard-bedded ice streams elsewhere in northern Canada.🏁

Submitted by azaya - 01/27/2025