Upper Plym Valley

History of Upper Plym Valley

Today the Upper Plym Valley is a typically treeless Dartmoor landscape, grazed by cattle, sheep and ponies. It is hard to imagine it 3,500 years ago dotted with settlements of neat round huts, with fields of crops growing near the river and herds of pasturing animals on the higher slopes; or, in medieval and later times, alive with the activity of rabbit farming and tin streaming.

The remains of a Bronze Age settlement near Trowlesworthy tor
The remains of a Bronze Age settlement near Trowlesworthy tor

The Upper Plym Valley has an extraordinary concentration of stone remains littered across an area of 15.5 square kilometres (6 square miles), making it one of the richest archaeological landscapes of Dartmoor. The area extends from the source of the River Plym down to the china clay pits at Lee Moor, a distance of some 7 kilometres (4.5 miles).

The remarkable survival of so many sites is due largely to the lack of agricultural or industrial activity on the moor in modern times, which has meant that many of the prehistoric and later monuments have been left undisturbed.

Most of the remains belong either to the Bronze Age (about 2300–700 BC) or the Middle Ages. Some indication of the level of activity that once took place here was provided by an archaeological field survey undertaken between 2001 and 2002, when more than 300 monuments dating chiefly from these two periods were recorded.

The double stone row at Trowlesworthy
The double stone row at Trowlesworthy

The Bronze Age

There are especially well-preserved concentrations of Bronze Age settlements and enclosures on Trowlesworthy, Willings Walls and Hentor warrens. The enclosures consist of low, fragmentary walls made of large boulders while the settlements consist of hut circles, with small terraces in the hillsides enclosed by low rubble or slab walls.

There are also many funerary monuments, represented by small, roughly circular cairns or mounds of stone. The best-preserved examples contain box-like burial chambers made of granite slabs, and have retaining circles of upright slabs around them.

Dartmoor has a greater concentration of surviving stone rows than anywhere else in Britain, but their purpose largely remains an enigma. Two stone rows lie on the gentle slope 0.5 kilmetres south of Great Trowlesworthy Tor and one of these has a small stone circle of eight stones at its northern end. Along with stone circles and some of the more elaborate funerary monuments they form what must have been deeply significant ritual areas, possibly the scenes of religious ceremonies.

Some of the most distinctive Bronze Age remains on Dartmoor are the low, stony, earth-covered banks known as reaves. Made up of granite boulders and layers of turf, these were probably property boundaries, and can be seen running for miles across the moorland. Over 200 kilometres (125 miles) of reaves have been identified on the moor. A good example here is Trowlesworthy Reave, which crosses the moor on the hillside below Shell Top. Elsewhere on the moor and on its fringes, many field boundaries in use today still follow the line of ancient reaves.

Medieval and Later Remains

There is a notable absence in the Upper Plym Valley, as elsewhere on Dartmoor, of remains from the Iron Age and Roman periods. Archaeologists have speculated that this might relate to a deterioration in the weather, leading to a retreat to the more easily farmed soils of the lowland.

Whether because of more favourable weather conditions or of population growth, there is much evidence of occupation and activity in medieval times. The lower, western, end of the Upper Plym Valley was gradually resettled from the 13th century, and at least six farms or smallholdings were established in the area up to the 18th century.

Of these only the earliest, Trowlesworthy, established in 1272, remains in use. The farmhouses are all of a similar design, a long rectangular building with a single entrance in the southern side. Around them are often smaller ancillary buildings and beyond these are the remains of their fields.

At Hentor the fields contain the most complete examples of ridge and furrow (strip cultivation) on Dartmoor.

From the 16th century most of the farms in the Upper Plym Valley were converted into rabbit warrens. The rabbits, much valued for their meat and fur, were housed in low, rectangular earthen mounds known as pillow mounds: several hundred of these are scattered all over the Trowlesworthy and Hentor areas.

The small, cross-shaped lines of stone built up against walls and enclosures within the warrens are the remains of traps used to catch vermin which might attack the rabbits: the walls encouraged foraging animals into the long stone traps, which had slate shutters operated by the animals tripping a mechanism of levers and string.

All along the floodplain of the Plym are ridges of stone and massive delvings into the river deposits. These are evidence of the tin-streaming industry that once flourished here and in the valleys all over Dartmoor, certainly from the 12th century and possible even in prehistory.

The granite of the moor, as elsewhere in the South West, contains casserite (tin dioxide ore) which could be washed out of the gravel of the stream beds.

As the valley was worked, large amounts of waste gravel accumulated, and were piled into stone banks. The tin ore was taken away to be crushed at stamping mills – one of which lies just above the confluence of the Plym and Shavercombe Brook – and smelted at workshops known as blowing houses. The remains of one blowing house are visible higher up the valley where the Langcombe Brook joins the Plym.

Further Reading

Butler, J, Dartmoor Atlas of Antiquities (Devon Books, 1991–4)

Dartmoor National Park Authority, A Guide to Archaeology of Dartmoor (Devon Books, 1996)

Gerrard, S, Dartmoor (Batsford/English Heritage, 1997)

Greeves, T, The Archaeology of Dartmoor from the Air (Devon Books, 1985)

Griffith, F, Devon’s Past: An Aerial View (Devon Books, 1988)

Sale, R, Dartmoor: The Official National Park Guide (Pevensey Press/David and Charles, 2000)


The text on this page is derived from the Heritage Unlocked series of guidebooks, published in 2002–6. We intend to update and enhance the content as soon as possible to provide more information on the property and its history.

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