Early Pleistocene

Middle Pleistocene

Late Pleistocene

Quaternary of the West Shetland Platform

North Sea drill core

Quaternary of the northern North Sea

The Quaternary deposits found on the East Shetland Platform are thin (Johnson et al., 1993).  The Quaternary thickens above the Viking Graben to as much as 300m and provides a long and relatively detailed record of glaciation.

The sediments at the start of the Quaternary are sandy and point to a dominance of non-glacial marine environments. A later unconformity may relate to glaciation of Shetland at some stage in the Early Pleistocene but the timing of this event is unclear. The Middle Pleistocene starts at 730 ka and the sediments point to a range of glacimarine and marine interglacial environments. Stiff clay-rich units, with sand lenses, gravel and shell fragments probably relate to ice advances spanning the period between the start of the Cromerian Complex and the Elsterian on the north European record. The top of the Middle Pleistocene sequence is marked by a prominent seismic reflector attributed to erosion by Saalian glacial ice. The Saalian glaciation appears to have been the most significant erosional event in the northern North Sea (Johnson et al., 1993) and, by extension, Shetland.

The last interglacial is represented by laminated fine-grained sediments east of Shetland containing foraminifera of warmth-loving species. Another strong seismic reflector is developed across these and older units and is associated with deep channels, possibly tunnel valleys. Glaciation of Shetland and the adjacent shelf in the early Weichselian is indicated. Ice had retreated by around 30 ka, although marine fauna indicate cold water offshore, until the advance of the last ice sheet after 28 ka. This ice sheet reached a double maximum at 22 and 18 14C ka before retreat commenced around 15 ka.