Evidence for a Former Transgressive Dune Field: Shetland Islands, United Kingdom

Transgressive sand dunes result from a large disturbance of a significant coastal sand dune field. Sand blows landward, covering whatever it encounters, including agricultural fields, forests, or human habitations. This investigation is of a beach-dune system in the Shetland Islands of northern Scotland that is known from historic documents and archaeological excavations to have experienced a sand invasion during the Little Ice Age (LIA). Ground-penetrating radar observations suggest remnants of pre-LIA dunes and buried soils. Excavation of dunes and optically stimulated luminescence (OSL) dating of sand deposits confirm historic accounts but also document that the "event" lasted centuries. Geomorphological observations and OSL dates also indicate that earlier events occurred in this region, sometimes in association with known archaeological sites like Old Scatness and Jarlshof. Although the site studied is stable now, a sand invasion could occur again owing to increased storminess, removal of dune vegetation, or both. Mining of the dunes for aggregate places the contemporary beach in a more vulnerable position than earlier.