The Blackdown Hills, or Blackdowns, are a range of hills along the Somerset–Devon border in south-western England. The plateau is dominated by hard chert bands of Upper Greensand with some remnants of chalk, and is cut through by river valleys.
The Blackdown Hills were designated in 1991 as an Area of Outstanding Natural Beauty (AONB). In November 2023, AONBs became National Landscapes. The hills support an extensive range of wildlife leading to the designation of 16 Sites of Special Scientific Interest (SSSIs).
There is evidence of human occupation since the Iron Age. Fortifications include the remains of ancient hill forts, Norman motte-and-bailey castles and Second World War airfields. There are also religious buildings such as Dunkeswell Abbey and village churches. The hills are crossed by a network of minor roads, and major transport routes including the M5 motorway run around the periphery.
Natural region The Blackdowns form a natural region that has been designated as a national character area – No. 147 – by Natural England, the public body responsible for England's natural environment. Neighbouring natural regions are: the Devon Redlands to the west, the Vale of Taunton and Quantock Fringes to the north, the Mid Somerset Hills to the northeast, the Yeovil Scarplands to the east and the Marshwood and Powerstock Vales to the southeast.South West National Character Area map at naturalengland.org.uk. Accessed on 5 Oct 2013Blackdowns at naturalengland.org.uk. Accessed on 5 Oct 2013NCA 147 Blackdowns at naturalengland.org.uk. Accessed on 5 Oct 2013
Geography
Straddling the border of Somerset and Devon, the Blackdown Hills AONB covers an area of . The hills reach their highest point of above sea level at Staple Hill in Somerset. The hills in the southern part of the area, near Honiton in Devon, are more gentle. The Blackdown Hills are a sparsely populated area; much of the land is used for dairy farming.
The River Culm rises at a spring () near Culmhead and flows west through Hemyock, then Culmstock to Uffculme before joining the River Exe on the north-western outskirts of Exeter. The name of the river is thought to mean 'knot' or 'tie', in reference to the river's twists and loops; or is derived from a Celtic river-name meaning winding stream. The River Otter rises near Otterford, where a stream feeds the Otterhead lakes: (). It then flows south for through East Devon to the English Channel at the western end of Lyme Bay. The Permian and Triassic sandstone aquifer in the Otter Valley is one of Devon's largest groundwater sources, supplying drinking water to Taunton. The other rivers are the River Yarty and the Corry Brook.
Villages in the northern, Somerset part of the hills include Staple Fitzpaine, Buckland St Mary, Whitestaunton, Wambrook and Churchstanton. The larger, more southerly area in Devon includes Dunkeswell, Luppitt, Upottery, Smeatharpe, Hemyock, Blackborough, Yarcombe, Membury, Stockland, Sheldon, Cotleigh and Chardstock.
Geology
The geology of the Blackdown Hills together with the adjoining East Devon AONB is unique in south-west England, forming part of the only extensive outcrop of Upper Greensand in the region.
The Blackdown Hills form a flat plateau dominated by hard chert bands, made up of clay with flints, of Upper Greensand with some remnants of chalk. The Cretaceous rocks rest over eroded Jurassic and Triassic beds, with an outcrop of Rhaetian beds. In the western areas the Upper Greensand is devoid of calcareous material but the sands yield fossils of marine bivalves and gastropods (snails) preserved in silica. A high proportion of the steeper slopes of the Blackdowns are affected by landslides, the long northern scarp of the range in particular. Typically there are patchy deposits of head (clays, sands and gravels of local origin) found beneath the affected sections of slopes.
Climate Along with the rest of south-west England, the Blackdown Hills have a temperate climate that is generally wetter and milder than the rest of England. The mean temperature is approximately 10 °C (50 °F) and shows a seasonal and a diurnal variation, but because of the modifying effect of the sea the range is less than in most other parts of the United Kingdom. January is the coldest month with mean minimum temperatures between 1 °C (34 °F) and 2 °C (36 °F). July and August are the warmest months, with mean daily maxima around 21 °C (70 °F). December is normally the most cloudy month and June the sunniest. High pressure over the Azores often brings clear skies to south-west England, particularly in summer.
The average annual sunshine totals around 1,600 hours. Rainfall tends to be associated with Atlantic depressions or with convection. In summer, convection caused by solar surface heating sometimes forms shower clouds, and a large proportion of rain falls from showers and thunderstorms at this time of year. Average rainfall is around . About 10–20 days of snowfall is typical. From November to March, mean wind speeds are highest; winds are lightest from June to August. The predominant wind direction is from the south-west.
Ecology
There are 16 Sites of Special Scientific Interest (SSSIs) in the Blackdown Hills ranging from the Black Down and Sampford Commons to Reed Farm pit at just less than . This British conservation designation is administered in England by Natural England for areas with significant ecological characteristics deemed worthy of protection from inappropriate development or from other damage, and (since 2000) from neglect, under the Countryside and Rights of Way Act 2000. In total they cover , or just under 2% of the AONB. Of these SSSIs, 79% were deemed by Natural England's predecessor body, English Nature to be being positively managed.
The grasslands, heathland, meadows and mire support extensive populations of birds such as barn owls (Tyto alba) and nightjar, with butterflies including marbled white (Melanargia galathea), green hairstreak (Callophrys rubi) and the gatekeeper butterfly (Pyronia tithonus). The flora includes the heath spotted-orchid (Dactylorhiza maculata), corky fruited water dropwort (Oenanthe pimpinelloides), green-winged orchid (Anacamptis morio), heather (Calluna vulgaris), lousewort (Pedicularis sylvatica) and bird's-foot trefoil (Lotus corniculatus). The hedgerows and woodlands are made up of ash, hazel (Corylus avellana), grey willow (Salix cinerea) and pedunculate oak (Quercus robur) which support populations of hazel dormouse (Muscardinus avellanarius), common lizards, siskin, stinking iris (Iris foetidissima) and the purple hairstreak butterfly (Neozephyrus quercus). The rivers and streams are home to kingfisher, otter and the Daubenton's bat.
Blackdown and Sampford Commons have extensive surviving examples of the heathland, carr woodland and marshy grassland habitats that have developed on the acidic soils overlying the Greensand and Keuper Marls of the Blackdown Hills. The heathland supports a typical invertebrate fauna, including a wide variety of butterfly species, and with spiders notably abundant. The site is regionally important for birds which favour heathland habitats.
Quants, a grassland clearing in a forestry plantation well known for its butterflies including Duke of Burgundy, marsh fritillary and wood white, is a candidate for Special Area of Conservation (cSAC). These are designated under the European Commission Habitats Directive (92/43/EEC) as internationally important habitats.
History
Paleoenvironmental studies have shown that organic material began to accumulate on the Blackdown Hills in the Mesolithic and Neolithic periods with areas of open meadow, grass land with small woodland components being identified. There are several Bronze Age burial sites including Robin Hood's Butts near Otterford.
Notable archaeological sites include the Iron Age hill forts at Membury Castle, Hembury and Castle Neroche. Hembury is a Neolithic causewayed enclosure near Honiton. It dates to the late fifth and early fourth millennia BC and is believed to have been the capital of the Dumnonii tribe. The fort is situated on a promontory to the north of and overlooking the River Otter, Devon at approx above sea level. It has given its name to some of the earliest Neolithic pottery in southern Britain. An Iron Age hill fort was later built on the same site.R.R.Sellman; Aspects of Devon History, Devon Books 1985 - - Chapter 2; The Iron Age in Devon. Map Page 11 of Iron Age hill forts in Devon includes Hembury. There has been archaeological evidence found on the site of Roman military occupation, suggesting a fort within the existing Iron Age site. It is now a scheduled monument.
Fourteen hill slope enclosures, dating from the Iron Age have been identified on the Blackdown Hills, and prehistoric remains, from about 100 BC, have been found in Hemyock.
Castle Neroche is a Norman motte-and-bailey castle on the site of an earlier hill fort near Staple Fitzpaine. The hill rises to on the northern escarpment of the Blackdown Hills. The castle was probably built by Robert of Mortain in the 11th century and probably went out of use in the 12th century. Around the crossroads at Staple Fitzpaine there are several large sandstone boulders. They are called devilstones and are said to have been thrown by the Devil from Castle Neroche. According to legend if you prick them with a pin they draw blood. English word 'Stapol' means pillar or post and it is thought likely that this gave the village the first part of its name. The second part of the name comes from the Fitzpaine family who owned the manor between 1233 and 1393.
A Roman bath house and Edwardian folly in the village of Whitestaunton were excavated by the archaeological television programme Time Team. There is also evidence of iron workings in the Romano-British period, at Dunkeswell, which radiocarbon dating has placed in the 2nd century. It has been suggested that these and other iron-based technologies gave the hills a fairly industrial landscape during the Romano-British period, providing a source of the name Blackdown Hills. Local iron ores were smelted at Hemyock in small bloomeries (furnaces) to produce pure iron until the Middle Ages.
At Simonsburrow a battle between the native Britons and King Ine's Saxon army, put an end (temporarily) to the Kings expansion to the west. In 710, Ine and Nothhelm fought against Geraint of Dumnonia, according to the Anglo-Saxon Chronicle; John of Worcester states that Geraint was killed in this battle.John of Worcester was a twelfth-century chronicler who had access to versions of the Anglo-Saxon Chronicle that have not survived to the present day. See Campbell (ed.), The Anglo-Saxons, p. 222. For the chronicle text, see Forester, Chronicle, p. 36. Ine's advance brought him control of what is now Devon, the new border with Dumnonia being the river Tamar.
Just to the north of Culmstock, at Culmstock Beacon, is one of a chain of Elizabethan beacons built to warn of possible invasion by the Spanish Armada. On 5 November 1380, King Richard II granted Sir William and Lady Margaret Asthorpe a licence to crenellate the Hemyock manor house, meaning the permission to fortify it. Over the centuries, Hemyock Castle had many notable owners including Lord Chief Justice Sir John Popham. During the English Civil War it was held for Parliament, subjected to a brief but brutal siege and eventually slighted to destroy its military value. Parts of the castle walls, towers and moat still remain. They are a scheduled monument and include displays of history and archaeology. The castle was also owned by General Sir John Graves Simcoe the first lieutenant-governor of Upper Canada in 1792. He is buried at Wolford Chapel near Dunkeswell. The chapel is now owned by the Province of Ontario.