The Isle of Purbeck, not a true island but a peninsula, is in the county of Dorset, England. It is bordered by 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 Flowers Barrow above Worbarrow Bay. The most southerly point is St Aldhelm's or St Alban's Head. It is suffering erosion problems along the coast.
The whole of the Isle of Purbeck lies within the local government district of Purbeck, which is named after it. However the district extends significantly further north and west than the traditional boundary of the Isle of Purbeck along the River Frome.
The geology of the Isle is complex. It has two coastlines, Discordant along the east and Concordant along the south. The northern part is Eocene clay
(Barton beds), including significant deposits of Purbeck Ball Clay
. Where the land rises to the sea there are several parallel strata of Jurassic
rocks, including Portland limestone
and the Purbeck beds. The latter include Purbeck Marble
, a particularly hard limestone
which is capable of being polished (although in geological terms it is not marble
). A ridge of Cretaceous chalk
runs along the peninsula creating the Purbeck Hills
, part of the southern England Chalk Formation
which includes Salisbury Plain
, the Dorset Downs
and the Isle of Wight
. The cliffs here are some of the most spectacular in England, and of great geological interest, both for the rock types and variety of landforms
, notably Lulworth Cove
and Durdle Door
, and the coast is part of the Jurassic coast World Heritage Site
because of the unique geology.
In the past quarrying of limestone was particularly concentrated around the western side of Swanage, the villages of Worth Matravers and Langton Matravers, and the cliffs along the coast between Swanage and St. Aldhelm's Head. The "caves" at Tilly Whim are former quarries, and Dancing Ledge, Seacombe and Winspit are other cliff-edge quarries. Stone was removed from the cliff quarries either by sea, or using horse carts to transport large blocks to Swanage. Many of England's most famous cathedrals are adorned with Purbeck marble, and much of London was rebuilt in Portland and Purbeck stone after the Great Fire of London.
By contrast, the principal ball clay workings were in the area between Corfe Castle and Wareham. Originally the clay was taken by pack horse to wharves on the River Frome and the south side of Poole Harbour. However in the first half of the 19th century the pack horses were replaced by horse drawn tramways. With the coming of the railway from Wareham to Swanage, most ball clay was dispatched by rail, often to the Potteries district of Staffordshire.
Quarrying still takes place in Purbeck, with both Purbeck Ball Clay and limestones being transported from the area by road. There are now no functioning quarries of Purbeck Marble.
A number of Romano-British sites have been discovered and studied on the Isle of Purbeck, including a villa at Bucknowle Farm near Corfe Castle, excavated between 1976 and 1991.
A large part of the district is now designated as an Area of Outstanding Natural Beauty
(AONB), but a portion of the coast around Worbarrow Bay
is still, after over 50 years, in the hands of the Army, and has not yet been acquired.
Other places of note are:
- Swanage, at the southern end of the peninsula, is a seaside resort. At one time it was linked by a branch railway line from Wareham; this was closed in 1972, but has now reopened as the Swanage Railway, a heritage railway.
- Studland: This is a seaside village in its own sandy bay. Nearby, lying off-shore from The Foreland (also Handfast Point), are the chalk stacks named Old Harry Rocks: Old Harry and his Wife.
- Poole Harbour is popular with yachtsmen; it contains Brownsea Island, the site of the first-ever Scout camp.
- Corfe Castle is in the centre of the Isle, with its picturesque village named after it.
- Langton Matravers, which was once the home of several boys preparatory schools until 2007 when the The Old Malthouse closed.
- Kimmeridge Bay, with its fossil-rich Jurassic shale cliffs, and site of the oldest continually working oil well in the world.