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 and perhaps Orkney 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.

Geology of Orkney

  • Orkney Stratigraphy

    The Orkney Islands consist almost entirely of sedimentary rocks and subordinate lavas and tuffs of Middle and Upper Old Red Sandstone age. A Basement Complex composed of metamorphic rocks of Moinian type and Caledonian granites forms a number of small inliers near Yesnaby and Stromness in West Mainland and on the island of Graemsay.

  • Devonian environments

    During the Devonian Period, North America and Northern Europe were joined together forming Euramerica, one of the three major continental masses on the Devonian globe, with Orkney placed south of the equator. Most of Britain formed part of this landmass with mountains in the northwest and the open marine Devonian Sea covering southwest England.

  • Permian dykes

    The age of the Orkney dykes is 252+/-10 million years, placing the time of intrusion in the late Permian, a period of renewed tectonic movement in the sedimentary basins to the west of Orkney.

  • Hydrocarbon Potential

    The Petroleum System consists of four main Geologic components, source, reservoir, seal and trap plus additional processes necessary to generate and store hydrocarbons in the subsurface. Their presence is required to generate a viable EXPLORATION TARGET.

  • Tertiary of the northern North Sea

    At the opening of the Tertiary chalk sedimentation continued on the northern North Sea. Starting around 63 Ma, the East Shetland Platform was uplifted and tilted towards the south-east. ...

  • Mesozoic of the northern North Sea

    Rifting in the Northern North Sea commenced during the early Triassic, peaked during the late Jurassic, and terminated by the late Cretaceous. The Viking Graben can be seen as a failed arm of proto-Atlantic rift. Almost throughout this period, the Shetland area formed an area of positive relief.