139 - Marshwood and Powerstock Vales : Description

Physical and functional links to other National Character Areas

The Marshwood and Powerstock Vales National Character Area (NCA) is set within a series of Upper Greensand and sand/limestone ridges and hills which link this NCA to its neighbours. To the north and west, a broad Greensand ridge separates the area from the Yeovil Scarplands and the Blackdowns NCAs. Eastwards, strata of clays, sands and limestones create terraces, stepping up to the great expanse of the Chalk which continues into the adjacent Dorset Downs and Cranborne Chase NCA.

A short but complex coast includes Golden Cap, the highest point on the south coast at 191 m, offering long views up and down the coast and inland; Dartmoor is visible on clear days. West Bay marks the beginning of Chesil Beach, 28 km of shingle beach fronting the Weymouth Lowlands NCA and joining the Isle of Portland NCA to the mainland.

The South West Coast Path National Trail runs along the coast and the Wessex Ridgeway runs northwards from Charmouth into the adjacent Dorset Downs and Cranborne Chase NCA.

The NCA is within the Portland Bill to Dawlish Warren coastal cell, where littoral drift is generally eastwards and sediment transport along the coast is low and intermittent.

The principal transport links in the NCA keep to the higher ground and have avoided the Marshwood Vale, the main axis being along the coast via Bridport and along the Brit Valley to Beaminster. Electricity pylons cross the NCA from west to east.

Ham Hill Stone, from Ham Hill in the Yeovil Scarplands NCA, is a frequently used building material in this NCA.

The Marshwood and Powerstock Vales today

Along the coast, the busy A35 links Lyme Regis, Charmouth, Chideock and Bridport and provides access to the coast at various points. The road ascends and descends the Greensand hills which form prominent headlands on the coast, Golden Cap at 191 m being the highest. Between these headlands, areas of less resistant strata, devoid of the protective Greensand capping, often slump – classically at Charmouth, where landslips leave dramatic, stepped undercliffs. The beaches are characterised by the sudden appearance and gradual erosion of landslipped material.

This constantly evolving coast features 348 ha of maritime cliff and slope habitat, hosting outstanding assemblages of rare invertebrates such as beetles, solitary wasps, bees and moths, which thrive on the warm, southfacing cliffs. These are part of the Sidmouth to West Bay Special Area of Conservation (SAC).

In addition to internationally important biodiversity, the whole coastline of the NCA is part of the West Dorset Heritage Coast and the Jurassic Coast World Heritage Site, inscribed for its geological and geomorphological features. The South West Coast Path National Trail is the main resource for both access and recreational activity in the NCA. West Bay, Eype, Seatown and Burton Bradstock all lie on the trail and host holiday parks with static caravans and touring pitches.

Inland from West Bay sits Bridport, the principal town of the NCA. Bridport and Beaminster are the only places where significant urban expansion has occurred in the last 60 or more years. Bridport is a bustling local centre where visitors come to stay and to shop. The high street features some fine vernacular buildings that reflect the town’s past status and wealth. Beaminster is, by comparison, quiet and less visited but also features some fine examples of local vernacular.

The Marshwood Vale is a bowl-shaped, clay vale of verdant, gently undulating pasture. Thick hedgerows punctuated by standard oaks bound evenly sized fields. This is an intensely rural and pastoral area, characterised by small villages, hamlets and isolated farmsteads of Upper Greensand Chert – the favoured local building stone. Away from the few main roads, which can be unexpectedly busy, the vale’s character is overwhelmingly tranquil and remote.

The agricultural soils formed on the clays of the Marshwood Vale are highly productive and have been exploited to the full, leaving little in the way of extensive tracts of semi-natural habitat, although the hedgebanks and road verges form a network of semi-natural grassland and tall herb communities. The heavy soils of the Marshwood Vale favour oak, which is the dominant hedgerow tree.

The rivers Brit and Char run their entire courses across the clay vales. Both have relatively small, unmodified courses and both can flood rapidly in response to rainfall events. The Brit Valley running between Bridport and Beaminster, is the focus of the area’s limited arable farming and orchards.

Around the clay vale rise hills and ridges of clays, sands and limestones, presenting a complex and subtle mosaic of agricultural and semi-natural land cover. This landscape is older than the clay vale; small, irregular, pasture fields divided by overgrown hedgerows and small copses can be found – a fine example being at Fishpond. Small villages are found along the valleys, particularly where several valleys meet. Beaminster is a particularly clear example of this characteristic.

On the east of the NCA, a sequence of strata leads from Jurassic clays to the Chalk of the Cretaceous. Erosion has created a series of ‘terraces’ which are, in places, dissected and blurred by an intricate network of valleys. Around North Poorton and Powerstock (villages with a vernacular of the local Inferior Oolite), the greatest sense of remoteness and isolation can often be felt. The combination of enclosing steep valleys, winding lanes – often running in hollow ways – and extensive woodland cover obscuring the long views insulates these villages from their surroundings.

Much of the 6 per cent woodland cover in this NCA is concentrated here. Due to the underlying geology, the woodland here is wet, sitting on or below the springline, featuring oak and ash but locally dominated by alder carr. Such is the quality of this woodland and species-rich fen around Powerstock Common that a large tract has been designated as the West Dorset Alder Woods SAC.

This wooded landscape, along with the extensive hedgerow network, supports several scarce species of bat and the common dormouse. Agriculturally, the Powerstock Hills are almost entirely in pasture and, as with all the rising ground in the area, feature a mosaic of improved, semi-improved and semi-natural grasslands, often changing type within the boundary of a single field. Open habitats along the springline are also valuable: dry grassland rapidly gives way to wet meadows, mires and scrub, punctuated by numerous small, wet woodlands – often representing abandoned fields. Unimproved grassland communities represent 4.8 per cent of the NCA. Most of this is concentrated away from the fertile, improved pasture of the clay vale.

The most well-known and extensive area of this habitat, straddling the northeastern boundary of the NCA, is Kingcombe Meadows (Toller Porcorum Site of Special Scientific Interest), a 177-hectare complex of grasslands, wetland and woodlands managed by the Dorset Wildlife Trust.

On the highest ground of the chalk fringes of the Dorset Downs to the east and the flat-topped Greensand hills to the north and west are an impressive suite of hill forts, including Eggardon Hill, Pilsdon Pen and Coney’s Castle. Settlements are absent, being sited on or below the springline such as at Fishpond Bottom. The thin soils on the Greensand summits usually feature relict heathland, the acid conditions marked by a bold transition from rough pasture to bracken and gorse. Where management is absent, secondary woodland of birch and rowan has established. On the NCA’s north-western edge, conifer plantations have replaced rough grazing and heathland. Since 1953, the entire NCA has been part of the Dorset Area of Outstanding Natural Beauty (AONB), exemplifying as it does the landscape variety for which the AONB was designated.

This area’s remoteness and the popularity of the adjacent Dorset Downs and Cranborne Chase NCA have resulted in some neglect from the arts; however, Thomas Hardy mentions Bridport (Port Bredy) and Beaminster (Emminster) in his works and it also inspired some of William Barnes’ poems.

“Sweet Be’mi’ster, that bist a-bound
By green an’ woody hills all round,
Wi’ hedges, reachèn up between A thousan’ vields o’ zummer green”

(Lines from ‘Be’mi’ster’, Poems of Rural Life in the Dorset Dialect, William Barnes, 1879)
Both Hardy and Barnes would still recognise the Marshwood and Powerstock vales today, maintaining, as they have, their deeply rural, pastoral and tranquil character.

The landscape through time

The Marshwood and Powerstock vales are mainly underlain by Lower and Middle Jurassic clays, sandstones and limestones that were deposited between 195 and 165 million years ago and reflect a fall in sea level over this period. The Charmouth Mudstone Formation and Eype Clay were deposited in deeper water.

Shallowing seas deposited the Down Cliff, Thorncombe and Bridport sandstones These were capped by the Inferior Oolite limestone when sea levels reached their lowest. After this, Fullers Earth and Frome Clay marked a return to rising sea levels and subsequent Forest Marble to a further fall. The fossil record shows that these were highly biodiverse seas: invertebrates such as cephalopods (ammonites and belemnites) and bivalve molluscs were abundant while vertebrate remains include marine reptiles, fish and even rare fossils of early mammals.

Although sedimentation continued through the Jurassic, uplift and erosion at around 100 million years ago destroyed the record of the rest of the Jurassic and of the lower Cretaceous in this area. The rock layers were also tilted slightly to the east at this time. Marine deposition resumed across the new surface, laying down the Gault Clay, Upper Greensand and Chalk.

A geological structure known as the Marshwood Pericline has a strong controlling effect on drainage in the area. This elongated, dome-like structure was imprinted on the Jurassic geology by about 150 million years ago during a mountain-building episode. Early in the Cenozoic Era, a vast erosion plain developed, destroying much of the overlying Chalk, particularly in the west. This plain has been dissected following regional uplift but evidence of it remains in the western part of the NCA in the shape of the flat tops of the Upper Greensand capped hills, as at Golden Cap, Hardown Hill, Lewesdon Hill and Pilsdon Pen.

Erosion of the soft clays of the Charmouth Mudstone Formation has produced a broad vale rising to high hills capped by Upper Greensand. In contrast, the rivers and streams have cut down through the sandstones underlying the Powerstock Vale to create narrow, steep-sided valleys with flat hill tops capped by Inferior Oolite.

Surviving Neolithic barrows suggest that the Upper Greensand hills and ridges were cleared at an early date. Iron-age hill forts, such as Coney’s Castle, Pilsdon Pen and Eggardon Hill, form the most conspicuous other prehistoric artefacts. It is likely that subsequent settlement and cultivation have obscured other, less monumental traces of prehistory, though there is evidence for extensive prehistoric settlement at Beaminster.

The Romano-British period most likely saw extension of settlement and farming to most of the area, except the heavy, waterlogged soils of the Marshwood Vale. The main Roman road between Dorchester and Exeter passed through this area and occupation is known from the northern and southern edges of the area. Taylor suggests that Romano-British occupation of Dorset extended well into the 700s (significantly longer than in other parts of England).

The final transition to Saxon rule seems to have initiated only tenurial, ecclesiastical and administrative changes, making little difference to the majority of settlement and land use apart from many, though not all, place names changing from Celtic to Saxon.

The area’s villages and hamlets can mostly be dated to before the 11th century. The Norman invasion saw little physical change on the ground apart from the establishment or renaming of isolated farms with a typically Norman ‘hay’ ending (meaning ‘enclosure’). These frequent individual farms of Marshwood Vale are principally the result of 10th- to 13th-century assarting. Most fields associated with these scattered farmsteads are small to medium in size and often highly irregular in shape.

Moated sites, castles, deserted settlements, and remains of lynchets and ridge and furrow (for example, at Netherton and Powerstock) illustrate the degree of cultivation and more widespread settlement in marginal areas up to the early 14th century. Some farmstead sites show evidence of having shrunk from hamlets. This probably reflects rural depopulation due to the Black Death and increasingly urbanised populations.

Open field arable was restricted to areas around nucleated settlement such as Whitchurch Canonicorum. This was typically enclosed by agreement from the 15th century, often in a piecemeal fashion, resulting in small, rectilinear fields with gently curving boundaries. In the north of the area, common land was enclosed by agreement in the 17th century, resulting in a field pattern of regular, rectilinear fields that are more typical of late 18th- or 19th-century enclosure.

Arable cultivation has historically predominated in the Brit Valley and on lower ground, resulting in more large-scale enclosure generally completed by the 18th century. Hemp and flax growing were a major post-medieval aspect of agriculture on the area’s clay soils from the 17th century, supplying Bridport’s sailcloth and cordage-making industries. The NCA was a major dairying area from at least the 16th century, converting from cheese making to the production and export of liquid milk, facilitated by the extension of the railways into the area from the mid 19th century. Many farms still feature cider barns, as orchards were common and the production of cider was an important local custom.

This area, particularly the coast, has been the source of important fossils since the emergence of geology as a science over 200 years ago, and museums around the world contain fossils from this area. The first ichthyosaurs and plesiosaurs described by science were discovered here by Mary Anning in the early 1800s.

Apart from modest expansion of Bridport, Beaminster and Charmouth, the 19th and 20th centuries have had little impact on the area. There are, though, two notable exceptions. The steel pylons of the electricity transmission line, erected in the mid 1960s, run across both vales before making dramatic ascents of the rising ground either side of the NCA. The other is the dramatic increase in traffic on the A35 and the increasing levels of tourism and related development along the coastal strip; levels of near gridlock can be reached at the height of the tourist season.