The uninhabited island lies off the north coast of St Martin's. It is about and until comparatively recently was part of St Martin’s. In 1814 the area of the island was estimated as fifty acres. At the north-east end of the island a fragment of altered killas, which at one time covered a much wider area, could be seen in 1911. In common with the larger island, the place names are mostly English with the exception of Camper on the south-east coast and Porthmoren, a place on the west of the shingle and boulder bar that separates the two islands. In Cornishmoren is a girl, or maiden, and porth is a landing place. The north-west of the island rises to a height of and is topped by a ruined entrance grave. There are also other ancient monuments, including a chambered cairn and several other cairns, To the south, and sheltered by the hill, are six small mounds or cairns. Two walls indicating a bank and ditch field system are also present. An examination of one cairn in 1975 showed that it was about across, possibly double walled on the north side and probably too small to be a hut circle. Only part of the island is scheduled as an Ancient Monument, but the county archaeological unit has recommended that the whole island should be scheduled.
Natural history
White Island is designated as a SSSI because of the waved maritime heath, maritime grassland, breeding seabirds and for the sequence of Late Pleistocene deposits in the cleft of Chad Girt which almost cuts the island in two. The sequence of Quaternary deposits is as follows:
granitic head known as Porthloo Breccia; named after the site on St Mary’s
soliflucted gravel known as Hell Bay Gravel which consists of clasts and loess from glacial material in the Irish Sea
head with erratics named after the nearby site on St Martin’s.
Because it lies on the northern edge of the archipelago, the island is particularly exposed to high winds and salt spray. Consequently, the thin skeletal soil is covered in wind-blown maritime heath made up principally of western gorse, bell heather and heather. English stonecrop, bird's-foot trefoil and heath bedstraw can be found growing among the heath and gorse. On the deeper soils, bracken dominates, with bramble and honeysuckle. Along the western coast of the island is a small area of maritime grassland with the usual Isles of Scilly species of red fescue, thrift, common scurvygrass, buck’s-horn plantain and sea beet. In April 2001 the first confirmed Scillonian record of the RDB gilt-edged lichen was found on White Island. A widespread and frequent species in the tropics, often found in Macaronesia but rare on mainland Europe, this is a UK Biodiversity Action Plan Priority species and is protected under schedule 8 of the Wildlife and Countryside Act 1981.
