Assemblage of buried and seabed tunnel valleys in the central North Sea: from morphology to ice-sheet dynamics

Tunnel valleys are kilometre-scale, channel-like, incised subglacial landforms usually associated with glaciated lowlands (Ó Cofaigh 1996). Tunnel valleys related to the Pleistocene glaciations are present onshore and offshore of NW Europe (e.g. Huuse & Lykke-Andersen 2000; Van der Vegt et al. 2012). In the central North Sea, tunnel valleys are found buried in the Quaternary succession and as bathymetric deeps at the seabed. Three-dimensional (3D) seismic data from the central North Sea image extensive networks of buried tunnel valleys that consist of multiple generations of cross-cutting landforms (Stewart et al. 2013). Seabed tunnel valleys are identified in high-resolution bathymetric data, and form another set of younger glacial landforms. Morphological measurements of the buried and seabed tunnel valleys are compared to infer their relationship to past ice-margins and highlight the differences in ice-sheet configuration over time.