Isle of Purbeck

The Isle of Purbeck is a peninsula in Dorset, England. It is bordered by water on three sides: the English Channel to the south and east, where steep cliffs fall to the sea; and by the marshy lands of the River Frome and Poole Harbour to the north. Its western boundary is less well defined, with some medieval sources placing it at Flower's Barrow above Worbarrow Bay.^[1] John Hutchins, author of The History and Antiquities of the County of Dorset, defined Purbeck's western boundary as the Luckford Lake stream, which runs south from the Frome.^[2][3] According to writer and broadcaster Ralph Wightman, Purbeck "is only an island if you accept the barren heaths between Arish Mell and Wareham as cutting off this corner of Dorset as effectively as the sea."^[4] The most southerly point is St Alban's Head (archaically St. Aldhelm's Head).

From 1974 to 2019, the whole of the Isle of Purbeck lay within the local government district of Purbeck, which was named after it. The district extended significantly further north and west than the traditional boundary of the Isle of Purbeck along the River Frome. Following the abolition of the district on 1 April 2019, the Isle now lies within the Dorset unitary authority area.

In terms of natural landscape areas, the southern part of the Isle of Purbeck and the coastal strip as far as Ringstead Bay in the west, have been designated as National Character Area 136 – South Purbeck by Natural England. To the north are the Dorset Heaths and to the west, the Weymouth Lowlands.^[5]