THE FACE OF DORSET – ‘That special part of Dorset’
John Chaffey looks at the geological, ecological and historical diversity of the Isle of Purbeck
Published in November ’10
From Bournemouth’s cliffs, the casual observer will see a line of shapely hills to the south-west beyond the waters of Poole Bay. The chalk forming these heights can be distinguished in the white cliffs of Handfast Point at their eastern end. From there the summits of this ridge rise and fall westwards to give one of the most striking profiles in southern England. They form the central spine of that special part of Dorset, the Isle of Purbeck. Its name is derived from the Old English Purbik ‘beak-shaped ridge frequented by the bittern or snipe’. A glimpse at a map of Purbeck confirms the aptness of the name: the ridge of the Purbeck Hills indeed ends in a beak-shaped promontory.
From Bournemouth’s cliffs, low hillocky country to the north of the ridge can just be discerned, together with its sandy shoreline from Studland to South Haven Point. This landscape of sandy hillocks, gravelly plateaux and marshy valleys is Purbeck’s own heathland. A closer examination of the gaps at Corfe reveals further high land beyond – this is Purbeck’s limestone landscape that stretches away to its south coast. At a modest height, an airborne observer would be impressed by the east-west layout of Purbeck’s countryside. To the north lies the heathland, and immediately to the south is that lowland of pastures, coppices, neat stone farmsteads and occasional well-knit villages that runs from Swanage Bay in the east to Worbarrow Bay in the west: this is the verdant, fertile Vale of Purbeck. To the south-west is Purbeck’s remote and hidden gem, the clay lowland based on Kimmeridge.
Twenty million years ago great earth movements, powered from the south, pushed up Purbeck’s Jurassic and Cretaceous rocks into a huge fold with the strata dipping steeply to the north on the northern limb of the fold and gently to the south on its southern limb. Erosion has laid bare the rocks of the fold, still nakedly exposed at the coast and covered by heathland, grassland, woodland and man’s imprint inland. In the north the heathlands are underlain by the sands and clays of the so-called Poole Formation. Just north of the Chalk ridge, a narrow fertile belt of farmland is underlain by the London Clay and Reading Beds. The Chalk of the Purbeck Hills has been pushed into an almost vertical position by the strength of the earth movements. To the south of the ridge, the sands and clays of the Cretaceous Wealden Beds, so well-exposed in Swanage Bay and Worbarrow Bay, are hidden beneath the Vale of Purbeck. Beyond, the Purbeck Beds, of very early Cretaceous age, outcrop over much of the limestone plateau; to the south and along the coast they are replaced by the almost horizontal Portland limestone. Just emerging from beneath the Portland Sand at St Aldhelm’s Head are the dark shales of the Kimmeridge Clay, whose outcrop steadily widens towards Kimmeridge, and narrows again to disappear beneath the limestone bastions of Gad Cliff.
As a peninsula, Purbeck’s boundaries are easily enough defined on three sides. On the north it looks out onto Poole Harbour: to the east its coast varies from the dune-fringed Studland Bay, past the cliffs of the Foreland and Old Harry to the shores of Swanage and the crumbling cliffs of Durlston Bay. In the south is the Channel coast with fine and much varied cliff architecture from Durlston Head to St Aldhelm’s Head and beyond, to the western boundary of Purbeck at the secret and lonely cove of Arish Mell under the constantly falling cliffs of Cockpit Head. Beyond Arish Mell to the west, Purbeck’s chalk ridge – perhaps its defining feature – broadens out into cultivated downland to the west of Lulworth. Tradition has it that the tiny stream of Luckford Lake, which empties into the Frome, is the western boundary of Purbeck. The water-meadows of the Frome limit true Purbeck to the north and define its boundary through to Poole Harbour.
The heathlands extend from the eastern banks of Luckford Lake through to Studland Heath. To walk across Hartland Moor is to experience the wild and lonely ‘Great Heath’ that Sir Frederick Treves described. The heathlands in the west echo to the alien sounds of tank gunfire; further to the east they are protected for all time in the National Nature Reserves of Stoborough, Hartland Moor and Studland Heath. Here the Dartford Warbler finds an ideal habitat in the gorse thickets together with the stonechat, nightjar and the woodlark.
Apart from the patches of farmland that have been won from the heathland, other intrusive elements have brought change to the landscape. Ball clay, used for the manufacture of good-quality china and earthenware, has been worked in the Purbeck heathlands since Roman times and several large pits still remain, such as Povington in the Lulworth Ranges, Dorey’s Farm and Arne. The exploitation of oil in the Wytch Farm oilfield in the closing decades of the 20th century has had far less impact than the working of ball clay: well sites and gathering station are well-screened and, by the middle of the present century, there will be little evidence that Britain’s largest onshore oilfield ever existed.
The Purbeck Hills’ profile owes as much to the gaps at Ulwell and Corfe Castle as to the surging crests of the hills. Each stretch of the hills possesses its own character. In the east Ballard Down has its own limitless panoramas: E. M. Forster, in Howard’s End, thought that this was the finest place to show England to a foreigner. Westwards beyond Godlingston Hill, Ailwood Down carries its remarkable collection of long barrows and round barrows – an evocative and mystical place. Corfe Castle, standing on its own mound between East Hill and West Hill, dominates the central part of the Hills, and its stark ruins are an unforgettable sight when seen for the first time. Westwards, the Hills gradually take on a more remote character, with Bond’s 1740 Grange Arch and the Iron Age fort of Flower’s Barrow still precariously dominating Worbarrow Bay.
The Vale of Purbeck is far from a uniform stretch of low-lying countryside. Bands of sandstone within the Wealden Beds form elongated whaleback ridges such as Windmill Knap to the north of Langton Matravers, and the feature on which Harman’s Cross is built. Westwards, the magnificent open space of Corfe Common, rich in Bronze Age round barrows, still remains uncultivated: further to the west, Steeple church stands on another sandstone ridge.
In the east, lines of farms mark the northern and southern limits of the Vale: in the south many of the ‘marble’ farms mark the sites of the working of Purbeck Marble in medieval times. In the western Vale lines of farms appear, with Barnston Manor to the west of Church Knowle said to be the longest occupied building in Purbeck. In the far west is the abandoned village of Tyneham, with its restored church, schoolroom and History Barn. In the south of Purbeck lies its bleak and virtually treeless limestone country. Still scarred by working quarries around Acton, it has a remarkable history of stone working.
Abandoned quarries are now grassed over in the Townsend Nature Reserve to the west of Swanage and underground galleries or lanes still underlie parts of Swanage and Acton. Westwards the great open quarry at Swanworth is coming to the end of its working life and awaits meaningful restoration: cut into the constantly windswept plateau in the lee of St Aldhelm’s Head is its own quarry, still worked for its Portland Stone. Three villages cluster on the plateau. Langton and Worth Matravers still have the air of quarrymen’s villages, whilst Kingston, Purbeck’s hill village, has the aura of an estate village, dominated by St James’s, the so-called Cathedral of Purbeck.
Beyond the Portland Limestone escarpment running from Swyre Head to Tyneham Cap is Kimmeridge, set in a gently rolling landscape of fields cultivated for high yields of cereals. Kimmeridge Bay, rich in archaeology from the working of the bituminous Blackstone Shale, is dominated by the newly relocated and refurbished Clavell Tower, its 19th-century miners’ cottages at Gaulter Gap, and the oil well still yielding well beyond its allotted span of 25 years. Kimmeridge village is almost all thatched cottages, enriched by the smart new café and farm shop. Cuneliz to the east has the fine Smedmore House. Secreted away to the east in the shadow of Swyre Head is Encombe House set within its own Golden Bowl, one of the most dramatic locations of all of Dorset’s country houses.
Purbeck’s greatest appeal is in its variety of landscape. Its heathland recalls the New Forest, its Chalk ridge evokes memories of Surrey’s Hog’s Back, its central vale reminds us of the wooded Wealden lowlands of Kent and Sussex, and the limestone lands of the south hint at the Cotswolds and their stone villages. It is an effective microcosm of lowland Britain.