Shore platforms are an important element of the Orkney coastline. In the northern isles, platforms are developed along many kilometres of coast and virtually encircle some of the smaller islands, such as North Ronaldsay. Platforms occur even in sheltered locations, such as the shores of Scapa Flow. The platforms vary in size, with the Holm of Aikerness covering almost 0.5 km2. No consistent variation in width with orientation is obvious, although platforms are less developed on west-facing cliffed shorelines. On west Hoy, the intertidal shore platform is 40-70 m wide, with a partial cover of fallen boulders (May and Hansom, 2003).

Shore platform near Outer Urrigar on Eynhallow. Platform erosion by block removal is facilitated by the gentle dip of the sandstone to seawards.

On the exposed outer coasts of Orkney shore platform development is probably as rapid as anywhere in the world. Large scars from recent block removal are widespread. After storms, the platform surface carries many impact marks where blocks have been moved across its surface. The rear of the platform is also scoured whenever beach debris is dragged across it.

  • 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.

  • 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.

  • 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.

  • 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.