Quaternary geology of Prince of Wales Island, Arctic Canada

Abstract

The large physiographic elements of Prince of Wales Island consist of several stepped planation surfaces incised by broad meandering fluvial channels that predate formation of the archipelago. Erosion surfaces likely correlate with Sverdrup Basin Mesozoic elastic fills. Most of the island is covered by thick drift, largely till. A few subtill nonglacial deposits are likely Sangamonian. Wisconsin Glaciation left a single till sheet with three cross-cutting landscape assemblages, each recording a phase and direction of flow. Keewatin Ice flowed northwestward during phase I and was warm based except on the northern plateau; it formed megaflutes and a drumlin field. During phase 2, ice over phase I terrain was cold based but formed drumlin and ribbed moraine fields where warm based and a lateral shear moraine along the boundary, parallel to flow, between warm- and cold-based ice. During phase 3, the cold-based zone further encompassed phase 2 terrain and flow rotated suddenly by 90° and more because of capture of ice over the island by an ice stream in Gulf of Boothia. Where warm based, phase 3 and later ice formed drumlins and flutings under convergent flow across lower terrain; it formed ribbed moraine at the boundary of warm and cold-based ice at the head of a drumlin field, where flow was normal to the boundary. Phase 3 flow was beheaded before 11 ka, when the oldest end moraines were forming. The island occupies part of the tail of a zone of dispersion of shield debris, > 700 km from source, perhaps resulting from phases 1 and 2. During phase 3, debris was dispersed >120 km eastward from the island, most strongly in plumes representing ice streams. Till granule lithology best indicates dispersion. Postglacial sediments are mainly raised beaches with minor deltaic and alluvial sediment. Wetlands cap most fine glaciomarine and lacustrine deposits. A range of environmental concerns can be addressed using the surficial geology, which also provides a basis for planning mineral exploration.

Glacial and Sea Level History of Lowther and Griffith Islands, Northwest Territories: A Hint of Tectonics

“…But the youngest erratic shells, those with the lowest ratios, fall in group 2 of Dyke and Matthews (1987), which they interpreted to be of Sangamonian age. Paired Hiatella arctica shells with group-2 amino acid ratios in ice-proximal glaciomarine sediment below Wisconsinan Laurentide till on northeastern Prince of Wales Island yielded a uranium-series age of about 80 ka (Dyke et al, 1992). This age estimate supports the Sangamonian age assignment of amino-acid group 2 and places the Laurentide ice advance in the region in the Early Wisconsinan.…”

“…Still the patterns of ice retreat are profoundly different on either side of central and western Parry Channel. South of the channel, the ice retreat landforms indicate systematic withdrawal of Laurentide ice, abutted on northern Somerset Island by a large local ice cap (Dyke, 1983(Dyke, , 1984Dyke et al, 1992). North of the channel, the ice retreat landforms indicate only retreat of large island-centred local ice caps.…”

Formation mechanisms for ice‐stream lateral shear margin moraines

“…Here, Hodgson (1994) was the first to describe massive, extended ridges that border a drumlin field thought to have been produced by an ice stream, see Figure 2. He noted the similarity of these ridges to the one reported by Dyke and Morris (1988) and Dyke et al (1992) but also pointed out that the area outside of the ridges (and the ice stream) was probably not cold-based. This is because eskers are found outside and spanning the ice stream margin (see Figure 2).…”

“…The second explanation, therefore, postulated that the ridge marks the boundary between rapidly flowing warm-based ice to the north and east and slow-flowing cold-based ice to the south and west (Figure 1). Dyke and Morris (1988) and later, Dyke et al (1992) preferred this explanation, coining the term 'lateral shear moraine' and suggesting that the feature marks a curvilinear vertical shear zone at the lateral margin of an ice stream.…”

“…but this was rejected because there is strong evidence that the area outside of the drumlin field was not ice-free (see Dyke et al, 1992 for comprehensive reconstruction of glacial history). The second explanation, therefore, postulated that the ridge marks the boundary between rapidly flowing warm-based ice to the north and east and slow-flowing cold-based ice to the south and west (Figure 1).…”