The big wind trundled our pail, a clanging bell

Through the four crofts,

Broke the clean circles of wave and gull,

Laid the high hay in drifts,

Beat down the stones of the dead,

Drove the Beagle aground,

Whirled up Merran’s petticoats around her head,

And set three hen houses (cockerels raging aloft)

On the crested Sound

George Mackay Brown

Definition: one or more beach ridges above the level of high tides formed of boulders deposited during storms

The western coasts of Orkney possess a remarkable array of boulder beaches which reflect the frequency of high seas and the availability of bedrock for quarrying. The beach crests may extend many metres above sea level and merge into angular cliff top storm deposits.

Cliff-top storm deposits
Adrian-and-John-at-Yesneby-01 Cliff-top storm deposits

Westrays

The beaches showing the size sorting typical of beaches, with smaller shingle at the base of the beach. This material is rounded, reflecting the frequency of attrition as waves move the stones back and forward. The coarsest material forms the beach crest and here 1 m diameter boulders are not uncommon. These blocks may be less rounded, partly because only the biggest storm waves reach this part of the beach but also because blocks are often quarried by waves from the rocky shore in front of the beach and immediately thrown inland. A cover of lichen on the beach crest, notably the grey Leconara sp., indicates that the uppermost part of the beach has not been reworked for many decades.

Behind the crest may lie older blocks, partly embedded in turf, that mark where the largest historic storms have overtopped the beach ridges. Bay head storm beaches frequently form ayres and lagoons – these lagoons may show trash lines and retain a record of historic storms in the sediment on the pond floor.

  • The outer coast of Orkney is an outstanding location to study the erosion of hard rock coasts. Evidence of major erosion is not hard to find. The great bowl of Enegars corrie is losing its edge to the sea. The egg-shaped headland of Marwick Head is a dome half lost.

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  • Amongst the many beauties of Orkney are the beaches which fringe the bays and ayres of the inner coast. These are dynamic forms, changing shape with the seasons and gradually retreating landward as sea level rises.

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  • Orkney is a dissected landmass drowned by postglacial sea level rise. A drop in sea level of just 35 m would unite the archipelago into a single island. The individual islands may represent hills that formed the watershed areas of preglacial drainage basins but it is linear glacial erosion which has separated one island from another and severed Orkney from the rest of Scotland.

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  • World coasts have seen sea-level variation of approximately 100 metres within the past 11,500 years through melting of the ice caps. When the ice caps melt the sea level rises globally (eustatically). The relative sea-level at any location is measured proportionate to the nearby land, which is itself subject to tectonic movement both up and down.

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