137 - Isle of Portland : Description

Physical and functional links to other National Character Areas

The Isle of Portland National Character Area (NCA) (referred to as Portland) is physically connected to the Weymouth Lowlands NCA by a shingle spit between the island and Chesil Beach. The spit, which is vulnerable to wave overtopping, provides a barrier sheltering the land to the east from storm waves coming from the west. The road from Portland to Weymouth runs atop the shingle ridge.

There are wide views from Portland to its harbour, to Chesil Beach and the Fleet, to Weymouth and to the Purbeck Coast and further inland to the Dorset Downs.

The South West Coast Path National Trail, which extends from Minehead in Somerset to Poole Harbour in Dorset, runs around the island and locally links Chesil Beach with Weymouth Bay. The geology of the area gives Portland a sense of connection to the mainland.

The geology of Portland has a major influence on national architecture – Portland stone has been used across the country and in major buildings such as St Paul’s Cathedral and many other notable buildings in London, creating visual, historic and industrial links between Portland and the mainland.

Water to the Isle of Portland comes from the adjacent mainland. The supply is limited: the Catchment Abstraction Management Strategy indicates that there is no water available for further abstraction licences. Irrigation activity from public water supplies for horticulture would not be appropriate, so any new development on the Isle would need to source water from a more sustainable supply.

The two Special Areas of Conservation (SAC) that run around Portland’s coast, Chesil and The Fleet to the west and Isle of Portland to Studland Cliffs to the east, meet at the start of West Weare near Fortuneswell.

The Isle of Portland today

The Isle of Portland, which is dominated by the Verne Prison and the naval base, is a distinctive feature jutting out into the English Channel. In the north there are steep, rugged cliffs with immense fallen blocks of rock at their base. The plateau land slopes southwards, finally standing only about 10 m above the sea. Much of this rugged landscape is deeply scarred by centuries of quarrying. Slabs of light grey Portland stone are strewn across the largely treeless landscape. Hedges are absent and the land is divided into small fields by drystone walls, which are often in a poor state of repair, obscured by mounds of brambles and partially replaced by post and wire. The skyline is low, and buildings, signs, pylons and quarries tend to dominate the landscape. The main settlements are villages lying around the more sheltered northern and central areas. They, too, are dominated by local stone. Locally, particularly near the villages, there are closely grazed horse paddocks but, elsewhere, piles of quarried stones lie in the fields and small abandoned quarries are a conspicuous feature.

The top of the island is a plateau that slopes from its highest point of 136 m at the northern end of the island down to Portland Bill at the southern tip, where the rock continues underwater to form reefs. Portland Bill, the lowest part of the island, with its three former and current lighthouses, is the site of a bird observatory housed in the Old Lower Lighthouse. Pulpit Rock, a stack of rock, is a prominent landmark here. The tidal race (Portland Race) around the headland reaches speeds of up to 4 m per second. The sea here can vary from a flat blue ‘millpond’ in calm, sunny conditions at the turn of the tide to a spectacular seascape during violent winter storms when the tidal race is opposed by strong winds whipping up powerful waves. The landscape and seascape combine to give a unique sense of place.

The coast of Portland is part of the Jurassic Coast World Heritage Site, which showcases 185 million years of geological and palaeontological history, from the Permian at its western extremity to the Cretaceous at its easternmost point, in fewer than 100 miles.

The east and west coastlines of the island are very different. West Weare is a very rugged landscape. There are huge gullies in the cliff face, which have been caused by the natural processes of erosion and landslides but also by human influences, as huge quantities of quarry waste have been pushed over the cliff. East Weare is a more sheltered and gentler landscape.

Portland features important coastal habitats and grassland. The Isle of Portland to Studland Cliffs SAC supports species-rich Limestone grassland with wild cabbage, early spider-orchid and Nottingham catchfly. Chesil and The Fleet SAC is very rich in wildlife, with communities of aquatic plants and fauna specially adapted to brackish conditions. Large numbers of waterbirds overwinter here, and the shingle is a very important breeding site for little tern. Portland has only a secondary woodland of sparse and scrubby trees, with very few of these on the plateau itself. The rocky coastline and associated habitats are important for a suite of scarce and threatened moths, including the UK endemic micromoth Richardson’s case-bearer (a priority species) – Portland being one of two known sites where it is present. Another invertebrate special to Portland is the silver-studded blue butterfly. This protected species is normally found on heathland but there is another form that occurs on limestone grasslands; in England this form occurs only on Portland.

Hydrologically, the island is decoupled from the mainland aquifers by the impermeable Kimmeridge Clay. There are springs at the top of the clays, where water draining through the permeable rocks above helps to support vegetation for which areas of the island are notified as Sites of Special Scientific Interest (SSSI). There is not enough freshwater available on the Isle to supply the population, and therefore water, mainly sourced from the River Wey, is imported from the mainland.

There is some agriculture on the southern half of the island, with nationally important relict field systems. Their survival has been due mainly to the lack of fertility and productivity of the land here, which has resulted in continuing marginal coastal heathland/grassland farming. Portland sheep, a tough rare breed, traditionally grazed these areas. They are capable of enduring the exposed conditions and poor grasses while producing excellent meat and are able to lamb out of season. The breed is important for conservation grazing on heathland and for its potential adaptability to a changing climate.

Portland stone has been, and remains, of major importance. It was used by Sir Christopher Wren to build St Paul’s Cathedral, and many of the major Whitehall buildings are constructed from it. British war graves are always made from Portland stone, as are many military monuments, including the recently constructed Bomber Command Memorial. Quarries are therefore a key landscape feature, covering more than 50 per cent of the island’s surface. Many of these quarries are now worked out. Subsequent colonisation by scrub has ensued. Work to clear cotoneaster from the quarries and from the wider landscape is a major ongoing project; cotoneaster is an invasive shrub that thickly and widely covers the ground where it grows, displacing native fauna and obscuring the landscape and geological features. In addition to Portland’s statutory designations, almost the entire island is a Local Geological Site.

The innovative Portland Quarries Nature Park includes a sculpture quarry, featuring an Antony Gormley carving (The Falling Man), and opportunities for participating in sculpture workshops with the Portland Sculpture and Quarry Trust.

Portland is quite densely settled, with substantial stone villages at Fortuneswell, Weston, Easton and Southwell which dominate the open landscape. Use of local stone and a simple vernacular style of building results in uniformity in the settlements and a striking sense of place here. Urban influence thus rings the southern and northern sides of Portland Harbour, linked by the busy A354. Socio-economic status varies across the island – some of the settlements on Portland are high in Indices of Multiple Deprivation.

The adult prison, HMP Verne, opened on the highest point of Portland in 1949. Originally constructed as a prison camp in 1847, it became a Victorian fortress, armed with eight guns and other military features – for example the moat and gun emplacements, which are still present. The harbour, built between 1848 and 1905, is protected by a series of large concrete breakwaters. It is no longer used by the Royal Navy. It is very popular for recreation, including windsurfing and kitesurfing. Portland Harbour and Weymouth Bay were the venues for the yachting and windsurfing events at the 2012 Olympic and Paralympic Games and are the venues for the 2016 Vintage Yachting Games.

The landscape through time

Portland is very much a product of its geological history, which records a gradual change from deep seas to coastal swamps with a fall in sea level at the end of the Jurassic Period.

The oldest rocks of the island are Upper Jurassic Kimmeridge Clay, which across its extent is economically important for its associated oilfields and which is very fossiliferous, having yielded – among other fossils – dinosaurs and marine reptiles. These sediments were followed by the Portland Beds – dolomitic Jurassic sands – as the seas shallowed and, as they shallowed further still, limestones laid down in clear, warm seawater. These limestones also contain the famous giant Titanites ammonites and many examples of the Portland screw, and have yielded rare reptile material.

The Purbeck Beds, above the Portland Beds, are a mix of terrestrial, lagoonal and marine sediments, marking a clear change in environment. They contain the remains of a prehistoric forest, dinosaur footprints and other fossil plants, such as the tree now placed outside the Portland Heights Hotel, and stromatolites (fossilised layers of blue-green algae trapped in sediment, forming mounds) around former tree trunks. This entire succession was laid down horizontally. The resulting plateau was tilted as part of an anticline folded during the Alpine Orogeny (mountain-building episode) some 25 million years ago.

Above the bedrock deposits lies the Quaternary geology. Chesil Beach, at the northern tip of the island, is a tombolo, or beach barrier bar, that was pushed northwards as sea levels rose at the end of the last ice age. At the southern tip of the island there are deposits of head (a mixture of sediments formed in valleys under periglacial climatic conditions). Near to the head deposits are raised beach deposits, which record sea level changes resulting from previous climate change. One major Quaternary event has left a very clear mark on the landscape; a large area of landslip at the north of the island extends along its east and west coasts, thinning out as the plateau lowers.

In terms of human influence on the landscape, there are Mesolithic shell midden and flint-working remains on Portland. There was a remarkably high density of Roman occupation and activity, Portland stone being highly prized by Roman builders; Portland stone has been quarried continuously since the Roman period at least. The use of Portland stone, which has been much used in many major ecclesiastical and government buildings across the south of England, including the buildings of the great departments of state, increased in the 12th century. Christopher Wren was a Portland quarry owner, and he used stone from here to build St Paul’s Cathedral. From the 17th century the stone was particularly favoured for its marble-like qualities, smooth finish and workability. Until the arrival of Merchant’s Railway in 1826, a very early industrial railway that transported stone to Castletown, the stone was transported by coastal shipping direct from the cliff-face quarries; Portland Bill provided particularly good access for this.

The present predominant pattern of nucleated settlement was established by the 13th century, the main settlements being villages lying around the more sheltered northern and central eastern side of the Isle. These have been subject to considerable 20th-century expansion. Farmsteads and hamlets, many of the former being of 19th- and 20th-century origin, are dispersed across the landscape. A historic relict field system of baulks and strips dating back to the medieval period is still in use in the present day, a reflection of the low levels of productivity and suitability for agriculture common across the area.

The Isle of Portland commands an important strategic position on the coast, forming a sheltered harbour to the east and controlling long-shore movements. The importance of the island for national defence increased after construction of the coastal fort in the 1540s, but the biggest impact on the landscape was consequent to the development from the 1850s of the Royal Naval port (which was originally a coaling station) and its associated breakwaters, as a counterpoint to the French naval dock at Cherbourg. The harbour was used as one of the embarkation points for Allied forces for the D-Day landings, and later, for several years until 2005, as the berth for HMP Weare, the UK’s only prison ship.

Other important military installations on Portland include the High Angle Battery, a short-lived installation designed to fire shells onto the decks, rather than at the sides, of enemy ships. The battery was built in 1892, only to be decommissioned in 1906, but remains a prominent feature. There was also a ROTOR radar installation on Portland, a short-lived and experimental defensive system. Most of the installation was concealed underground, with only the entrance bunker and “cottage”� above ground. The harbour was also the base for classified post-Second World War weapons research, which was at the centre of a notorious spy ring scandal that erupted in 1961.

The adult prison, HMP Verne, was originally constructed as a prison camp in 1847. It became a Victorian fortress, and military features such as the moat and gun emplacements are still present. There is also a Young Offender Institution on the island. Storage tanks at the northern end of the island have been removed, improving the vista across to Chesil Beach and the Fleet.

There is a current emphasis on nature reserve creation on Portland, and a quarry park and sculpture park have been created from former industrial landscapes.