Skjoldryggen terminal moraine on the mid-Norwegian shelf

Abstract

Terminal moraines are relatively large ridges of diamictic glacial debris produced at the outermost margins of past glaciers and ice sheets. Their identification on land is important in mapping the maximum extent of Quaternary ice sheets (e.g. Svendsen et al. 2004; Benn & Evans 2010). In marine environments where fast-flowing ice streams reach the shelf edge during full-glacial intervals, moraine ridges are not usually present and the seafloor is characterized by parallel-to-flow streamlined sediments (Ottesen & Dowdeswell 2009). Submarine terminal moraine ridges, by contrast, appear more typical of slower-flowing marine ice margins (Dahlgren et al. 2002; Dowdeswell & Elverhoi 2002; Dowdeswell et al. 2016). A very large ridge, about 150 km long and up to approximately 200 m high relative to the adjacent shelf, is located on the outermost part of the mid-Norwegian continental shelf edge between about 65° and 66° N (Fig. 1a). It is known as Skjoldryggen (‘skjold’ means ‘shield’ and ‘ryggen’ means ‘the ridge’ in Norwegian). Along most of its length, the ridge has a steeper offshore slope relative to …