Etset Lake (NTS 94P/11) map area was glaciated by the Laurentide Ice Sheet during the Late Wisconsinan (ca. 25 000-10 000 years ago), which deposited clayey till over most of the area. Glacial flutings in the east central part of the map area record the ice flow from the north-northeast. Much of the area is now flat and boggy, with peat accumulations of 2 to 3 m that form hummocky terrain underlain by discontinuous permafrost. Till underlies the surface of broad forested uplands. The uplands are usually only a few metres above the surrounding wetlands. Deglaciation was recorded by numerous small moraines and crevasse-fill ridges that mark the pattern of glacial retreat as the ice sheet thinned and the margin became lobed. A tongue of ice persisted in the broad lowland incised by the modern Petitot River. Meltwater issuing from the retreating ice margin cut several large channels trending northwest across the map area. The largest of these, now occupied by Sahdoanah Creek, was the main drainage when Petitot River to the north was still covered by ice. These former meltwater channels can have significant, but localized, accumulations of glaciofluvial gravels.
At about 10,000 B.P. northern Axel Heiberg and Ellesmere islands underwent a climatic amelioration that caused the demise of the last glaciation. Generally, by 8,000 B.P. accelerated retreat left extensive coastal areas ice free. The occurrence of an early Holocene (7475±220 B.P.) bowhead whale (Balaena mysticetus L.) skeleton several hundred kilometres north of its present range concurs with other biological and glaciological evidence to indicate that the early Holocene climate in the High Arctic was less severe than at present.
This publication utilizes lithostratigraphic information provided by the revised and updated seismic shothole drillers' log database (GSC Open File 6833), and two other borehole databases, to identify potential granular aggregate resources. Lithostratigraphic records are interpreted and presented in a GIS at two depth intervals; upper 10 m (76 958 records) and total shothole depth (89 019 records), and are distinguished by location (surface vs. subsurface) and sediment type (gravel; gravel + sand; sand). This point-stratigraphic information is augmented by including granular aggregate-associated surficial geology map polygons (e.g., glaciofluvial deposits) from published and in progress maps throughout the Mackenzie corridor and northern Yukon. Where shothole records intersect map polygons, they can confirm the existence of aerially extensive surface granular aggregate deposits, and by extension provide a characterization of their sedimentology and thickness. Where shothole data occurs outside of granular aggregate-associed map polygons they can identify sites potentially obscured by vegetation or missed during surficial geology mapping. They also identify deposits in areas that have yet to be mapped.
Sea‐ice ice shelves, at the apex of North America (>80° N), constitute the oldest sea ice in the Northern Hemisphere. We document the establishment and subsequent stability of the Ward Hunt Ice Shelf, and multiyear landfast sea ice in adjacent fiords, using 69 radiocarbon dates obtained on Holocene driftwood deposited prior to coastal blockage. These dates (47 of which are new) record a hiatus in driftwood deposition beginning ∼5500 cal yr BP, marking the inception of widespread multiyear landfast sea ice across northern Ellesmere Island. This chronology, together with historical observations of ice shelf breakup (∼1950 to present), provides the only millennial‐scale record of Arctic Ocean sea ice variability to which the past three decades of satellite surveillance can be compared. Removal of the remaining ice shelves would be unprecedented in the last 5500 years. This highlights the impact of ongoing 20th and 21st century climate warming that continues to break up the remaining ice shelves and soon may cause historically ice‐filled fiords nearby to open seasonally.
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