St Ninian's Isle tombolo
The largest active sand tombolo in the UK forms a beautiful landmark along the coast of southern Shetland.
A tombolo is a beach or bar created and maintained by wave action that connects two landmasses. The 500m long sandy tombolo at St Ninian's is subject to waves from two opposing directions. They break simultaneously along its length, resulting in beautifully symmetrical sweeping beaches facing north and south. The first known depiction of the tombolo is in a chart drawn around 1700. It formed as sea levels rose after the last ice-age but the forces that created it continue to work, making it the largest active sand tombolo in Britain. In winter sand is lost from the centre and builds up at the ends, while in summer the opposite occurs. During low tides it can be 70m wide, but during high spring tides the centre can become submerged. In the Northern Isles tombolos are usually formed from gravel, cobbles or boulders. St Ninian's tombolo is sand, though there is evidence for a gravel core beneath. Blown sand trapped by marram grass forms dunes at either end. They are more extensive to the east due to the dominance of westerly winds. Behind the dunes is machair - grassland with many wild flowers that benefit from the calcium in the sand.
St. Ninian's Isle is in the South Mainland and is signposted from the A970.