Paraglacial fluvial landscape change in a continuous permafrost environment around the ‘Twin Creeks’ catchment, Banks Island, western Canadian Arctic

Following Late Wisconsin glaciation of southwest Banks Island, four stages of landscape change are reconstructed for a small (c. 2 km2) tundra catchment draining a south facing slope in an environment underlain by continuous permafrost. Initially, during deglaciation, glaciolacustrine silts and sands were deposited on a proximal slope underlain by till (Unit A). Subsequently a cyclic sub-aerial fluvial erosional–depositional system developed. First, an alluvial fan aggraded unconformably on Unit A with penecontemporaneous growth of ice and sand wedges (Unit B). Second, deep incision of the fan created a network of steep-sided flat bottomed channels. Third, wetland fens developed on the channel floors and peats with a sandy aeolian component aggraded and largely infilled the channels (Unit C). Synchronously, on the interfluves a soil catena developed under a warmer climate in the early Holocene. This was later buried by coversands (Unit D). Fourth, in the late Holocene, entrenchment recurred and currently fluvial processes are both exhuming and extending the first phase channel networks. A combination of climate and vegetation cover changes appears to control the pattern of geomorphological process responses.