Synopsis

We present new multibeam bathymetry and boomer seismic profiles from 200 km2 of sea floor around the Summer Isles in NW Scotland. The data reveal an undisturbed marine landscape comprising overdeepened basins, grooves, moraines, pockmarks and slide scars. Collectively these features represent a Late Devensian fjord landsystem. In more detail, the basins and grooves represent focused subglacial erosion during successive ice-sheet cycles. A suite of moraines charts the retreat of a marine-terminating ice sheet at the end of the last glaciation (c. 15–18 000 bp). Pockmarks attest to the release of shallow gas from organic-rich proglacial sediments. Finally, slumps and slide scars demonstrate slope evolution following the retreat of the fjord glaciers. This slope instability, both onshore and offshore, continues to the present day. Ongoing work aims to unravel the detailed sequence of events in the Summer Isles region at the end of the last glaciation, with particular emphasis on the glaciology of The Minch palaeo-ice stream.

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