Some 4,500 years ago, a sandstorm overwhelmed a village at the Bay of Skaill in Orkney. People were forced to flee from their houses abandoning most of their possessions. In a hurry to leave through the low door of her home, one woman broke her necklace and left behind on the floor a stream of beads.

In 1850, another storm ripped open the sand dunes to expose some of these houses and later archaeological excavations revealed the best preserved prehistoric village in northern Europe, now known as Skara Brae. But whether the events that led to this ancient settlement being abandoned were quite as catastrophic as the woman’s beads imply may be open to question.

Skara Brae is vulnerable to sand blow as it lies on a flat grassy plain just above the beach. This type of landscape is called machair, and is peculiar to northwest Britain. Jarlshof in Shetland, Bosta in Lewis, Northton in Harris, Oronsay off Colonsay, numerous sites recently excavated in South Uist and many other west coast prehistoric settlements are all in similar locations.