Moat features, Amundsen Gulf, Canadian Arctic Archipelago

Abstract

Multibeam sonar imagery provides evidence of depositional and erosional seafloor features emplaced by a glacial ice stream that flowed through Amundsen Gulf into the Beaufort Sea during the last glaciation. Figure 1a, c illustrate seafloor features that occur SW of Banks Island in the northwestern part of Amundsen Gulf (Fig. 1b). Water depths in this part of the axial trough range from 350 to 435 m. Prominent seafloor landforms include parallel ridges and grooves that trend northwesterly across the region. Depressions up to 135 m wide and 45 m deep occur as irregular linear and arcuate-shaped interruptions in many of the ridges. The linear interruptions extend across adjoining ridges along trends that lie approximately normal to the trend of the ridges (Fig. 1a, c). Arcuate-shaped depressions (moats) connect with wider inter-ridge valleys trending to the NW. In many instances the linear ridges, apparently undiminished in height adjacent …