Section A

  1. 10 m clast-dominated to clast supported, poorly sorted angular to sub-angular cobble to boulder gravel. Near its base there are clasts of bedded sands and laminated clays
  2. 1-6 m stratified, medium, well-sorted sands with, near the top, laminated clays
  3. 1-5 m brown, matrix-supported, clast-rich diamicton. base not seen.

Section B (illustrated)

  1. 1 m silty fine sand with occasional small gravel.
  2. 3 m very bouldery, clast-supported, poorly sorted, angular to sub-angular gravel.
  3. 8 m reddish-brown, sandy matrix-supported clast-rich diamicton.
  4. 2-3 m beds of brown, matrix-supported diamicton interbedded with stratified sands and laminated clays.
  5. 1.5-2 m sandy, matrix-dominated diamicton with cobble- to boulder-sized clasts. The clast lithologies are dominantly sandstone but there is a significant component of volcanic rock fragments. A proportion of the clasts are weathered.
  6. weathered ashy sandstone bedrock.

Section C

  1. 12 m brown, sandy diamicton
  2. 3 m grey-brown diamicton with frequent volcanic rock fragments.

North Hoy viewed from the N on Google Earth

Enegars is the hollow on the far right (west) of the image. The valleys of north Hoy lead in the background towards Rackwick Bay

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

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

Enegars scallops the north side of Cuilags and faces almost due north. At its highest point the backwall is about 335 m high. The floor of the corrie is at about 100-120 m OD, an unusually low elevation for a corrie in Scotland. The lip of the corrie has probably retreated due to a combination of ice sheet and marine erosion and now falls sheer to the sea along the impressive sea cliffs that flank this part of of Hoy. Enegars may once have had an adjacent corrie to the west that has been lost to marine erosion. In the grandeur of its sandstone crags, Enegars is matched only by the Applecross corries developed in Torridonian sandstone.

Several moraine ridges lie within the corrie (Sutherland, 1993) which may relate to both a corrie glacier and a lobe of the last ice sheet flowing out of Scapa Flow. A lateral moraine (CLM1) from a former corrie glacier descends the SE side of the corrie for over 300 m. The largest moraine (LLM1) crosses the corrie lip at around 100 m OD and is up to 6 m high on its seaward margin and between 1 and 3 m high on the landward side. The moraine carries a scatter of sandstone boulders that are up to 2 m long and on which weathering pits up to 8 cm deep can be seen. Another arcuate moraine (LLM2) about 150 m long occurs on the SE slope inside the main one.

Stream sections reveal some of the sediments that form the moraines. Section A described by Sutherland (1993) and listed here is beneath the inner part of LLM1 and Section B is seawards of this, close under the outer part of the moraine.  To the east of the corrie at the head of the Bay of Tongue there is a drift ridge that extends from the foot of Lounders Fea to the coast where it is truncated by the marine cliff.  A poorly exposed section at the top of the cliff (HY20650470) has been described by Sutherland (1993) as Section C.

The poorly sorted, coarse to very coarse gravels at or just below the surface in Sections A and B are considered by Sutherland to be the sediments that comprise the moraine ridges.  The stratified sands and clays that immediately underlie these sediments in Section A are water lain and may relate to ponding at the margin of an ice lobe during ice sheet deglaciation.

The upper till at C, the two units overlying the basal till at B and the bottom till at A all resemble other tills observed in the north of Hoy. The presence of erratics of volcanic rocks shows that these tills were deposited the last ice sheet.

Sutherland (1991, 1993) suggested that the most likely age of the corrie glacier advance was during the Loch Lomond Stadial when other minor glaciers reoccupied corries elsewhere in the Highlands and Islands. This has been confirmed by recent reports of cosmogenic exposure ages (Ballantyne et al., in press).

Ice over Orkney

Key Geomorphological Sites

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

  • 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.

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

  • 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.

  • 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.

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

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

  • 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

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

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

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

  • Significance: a possible Scandinavian erratic on Orkney.

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

  • 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.

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

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

  • During the periods of maximum cold in the Quaternary, major ice sheets covered Scotland. An ice stream hundreds of metres thick curved out from the Moray Firth to cross the plain of Caithness and flow over Orkney towards ice limits close to the edge of continental shelf.

  • In the gently-dipping sandstone terrain of Orkney, it is often difficult to pick out classic landforms of glacial erosion. Low-lying areas often show a pronounced SW-NE grain to the topography, parallel to the main direction of ice sheet flow. ...

  • Glacial deposition is largely confined to low-lying areas on Orkney, where thicknesses of till may exceed 10 m. The glacial deposits drape the landscape, smoothing its outlines. Ice-marginal features are largely unrecognised outside Hoy ...

  • Westray is the furthest northwest of the Orkney islands. The total area is 47 square kilometres, not huge but the irregular shape gives it a long coastline of almost 80 kilometres, a good place to look for glacial striations. The bedrock of the whole of the island is made up of the cyclical Rousay Flagstone Formation. ...