Flannan Isles - Geography

Geography

The islands are split into three groups. The main cluster of rocks, which lie to the northeast, include the two principal islands of Eilean Mòr (English: Big Isle) and Eilean Taighe (House Isle). To the south lie Soray (Eastward Isle) and Sgeir Tomain, while the main western outcrops are Eilean a' Gobha (Isle of the Blacksmith), Roaireim (which has a natural rock arch) and Bròna Cleit (Sad Sunk Rock). The total land area amounts to approximately 50 hectares (120 acres) and the highest point is 88 metres (289 ft) above sea level on Eilean Mòr.

The geology consists of a dark breccia of gabbros and dolerites intruding Archaen gneiss. In pre-historic times the area was covered by ice sheets which spread from Scotland out into the Atlantic Ocean. After the last retreat of the ice circa 20,000 years BP, sea levels were up to 122 metres (400 ft) lower than at present and it is likely that the existing islands were part of a much larger land mass, although still separated from the Outer Hebrides by many miles of open water. Steadily rising sea levels would then have reduced the land remaining above sea level to its present extent.

There are two possible landing places to the east and west for yachts visiting Eilean Mòr, although this can be hazardous given the regular heavy swells.