Inherited coastal landforms
There is widespread evidence around Orkney of the emergence of erosional landforms at the coast from beneath a cover of till. Whilst long stretches of the Atlantic coasts are undergoing active erosion, more sheltered shores give examples of platforms, geos and even cliff lines that are currently being re-occupied by the sea. Raised beaches resting on raised rock platforms occur on Hoy but there are no known coastal features on Orkney above 10 m OD. Prominent abandoned cliff lines are evident from the bathymetry at around -10 and -50 m. Similar inherited landforms occur widely around the Scottish coast.
Sea level has fluctuated widely through the glacial and interglacial cycles of the Pleistocene. Rock platforms below, at and above current sea level reflect periods when sea level has become stabilised for an extended time at that level, allowing erosion to cut a prominent notch in the shoreline. For features close to present sea level, perhaps the most likely period of erosion was during the last interglacial around 125 thousand years ago.