Muckle Head, HOY
Significance: a raised beach deposit at 6-12 m asl buried by till

At Muckle Head (HY 213053) on the north coast of Hoy beach sediments occur at 6 m OD that must pre-date the last ice-sheet glaciation of the islands (Wilson et al., 1935; Sutherland, 1993; 1996). The sequence of sediments can be summarised as:

The basal gravel is a beach deposit. Overlying the beach gravels is a periglacial slope deposit (‘head’) and a glacial till. The sequence of events appears to be (Sutherland, 1993):

1. high sea level and deposition of the beach
2. sea-level fall,
3. onset of periglacial conditions with the formation of the slope deposits,
4. invasion of the area by ice and deposition of the till,
5. ice retreat and solifluction of the upper layers of the till in a cold climate
6. deposition of the capping sands.

The age of the deposits is unknown. The beach sediments clearly pre-date the last phase of ice-sheet glaciation of this part of Hoy which would make them pre-Late Devensian in age. The adjacent geo must also be an inherited feature.

To the east along the coast near Selwick (HY 225055) there is another exposure of raised beach gravels overlain by till. The gravels can be seen to rest on a bevelled rock surface which may be part of a raised shore platform.

Key Geomorphological Sites

  • Yesnaby

    Significance: a coastline noted for its Devonian geology and coastal geomorphology

  • Bay of Skaill, Sandwick

    Significance: this bay lies adjacent to Skara Brae and provides evidence of the interaction between coastal processes and human disturbance between 6600 and 4400 radiocarbon years ago. The settlement first re-emerged from the dunes after a storm in 1850.

  • Den Wick, Deerness

    Significance: this site provides evidence for changing ice-flow conditions during the last ice sheet glaciation

  • Churchill Barrier No. 4

    Significance: the construction of the Churchill Barriers started in 1940 and led to a fundamental change in the pattern of tidal flow around Scapa Flow. A range of coastal landforms have been created subsequently which illustrate the fundamental control of coastal configuration on the transport and deposition of sand.

  • Rackwick, Hoy

    Significance: Rackwick lies at the southern end of two major glacial breaches on Hoy. Its well-developed moraines indicate that at the close of the last glaciation two lobes of ice retreated northwards at a time when the Pentland Firth was probably still occupied by ice.

  • Old Man of Hoy

    Significance: The Old Man is the tallest sea stack in Britain, 137 m high

  • Enegars Corrie, Hoy

    Significance: a superb corrie formed at an unusually low elevation that was last occupied by a small glacier only 11,000 years ago

  • Ward Hill, Hoy

    Significance: Ward Hill provides examples of a range of active and fossil periglacial landforms. As the highest point on Orkney it also provides evidence of the thickness of the last ice sheet

  • Flaga, Hoy

    Significance: the site of a former small corrie glacier on Hoy

  • Dwarfie Hamars, Hoy

    Significance: the site of a small corrie glacier during the Loch Lomond Stadial

  • Muckle Head raised beach, Hoy

    Significance: a raised beach deposit at 6-12 m asl buried by till

  • Saville Boulder at Scar, Sanday

    Significance: a possible Scandinavian erratic on Orkney.

  • Otterswick, Sanday

    Significance: a peat deposit with willow boles formed 6500 years ago and now lying below sea level

  • Kilns of Brin Novan, Rousey

    Significance: the Kilns of Brin-Novan is an excellent example of an interconnected series of caves, arches and blow-holes which illustrate the sequential development of these features.

  • Mill Bay, Stronsay

    Significance: this coastal section provides perhaps the best available exposure of the shelly till which is characteristic of the eastern part of Orkney

  • The Nev, Westray

    Significance: exceptional cliff scenery and dramatic cliff-top storm deposits