Ancient Monuments

History on the Ground

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Pen-Twyn Earthwork

A Scheduled Monument in Crucorney (Crucornau Fawr), Monmouthshire (Sir Fynwy)

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Latitude: 51.9016 / 51°54'5"N

Longitude: -2.9879 / 2°59'16"W

OS Eastings: 332126

OS Northings: 223023

OS Grid: SO321230

Mapcode National: GBR F6.QCH9

Mapcode Global: VH78V.5G8L

Entry Name: Pen-Twyn Earthwork

Scheduled Date:

Source: Cadw

Source ID: 369

Cadw Legacy ID: MM064

Schedule Class: Defence

Category: Hillfort

Period: Prehistoric

County: Monmouthshire (Sir Fynwy)

Community: Crucorney (Crucornau Fawr)

Traditional County: Monmouthshire


The monument comprises the remains of a multivallate hillfort, which probably dates to the Iron Age period (c. 800 BC - AD 74, the Roman conquest of Wales). The Pen-Twyn Earthwork is situated in a commanding position at the southern end of the Hatterall Hill ridge. The ground slopes away from it to the west and south, and on the east side there is a steep natural scarp. The fort consists of an oblong area measuring 140m N/S by 70m E/W, enclosed by banks and ditches on three sides, with the E side bounded by the natural scarp. There is a dividing bank and ditch running E/W across the middle, which may be a later cross dyke.

Along the S side there are a series of scarps, the inner of which is 2.2m high, running all the way along the E side. At the E end is a circular hollow, 1m in diameter, immediately above the scarp. To the S of this inner scarp is a berm, 18m wide, and a second scarp, 1.5m high that continues the length of the S side, ending at the E end with a slight knoll that has a hollow on its east side. Outside this scarp is a berm, or a faint ditch, 6m wide and then another scarp 1.2m high. Immediately S of this scarp is a ditch 2m to 3m wide, and then a low bank 0.7m high. A field wall is located on the S side of the ditch.

At the south-east corner of the fort is a curving entrance way flanked by a bank 1.2m high to the east and a knoll, 4m high, on the west. The Offa's Dyke Path enters the fort here. The interior of the southern half of the fort is more or less flat, but with a series of hollows 1m deep along the east side. Across the middle of the fort is a bank and ditch, which runs WSW/ENE, curving slightly northwards at the S end. The bank, which is located immediately N of the ditch, is 1m high on its N side and 2m high on the S side. The ditch is 1.5m wide and 1m deep.

At the N end of the fort there is a more massive bank, 2.5m high on the S side and 3m high on the N side, with an external ditch on the N side 2m wide and 1.5m deep. At the west end is a gap 1m wide and 1.2m deep, through which the Offa's Dyke path runs. To the S of the bank and ditch, inside the fort, is an area of bumps and hollows, with some bare rock showing. The rest of the interior of the northern end is more or less flat.

Along the W side there is a bank with an interior height of 0.7m and an exterior height of 3m. This has a farm track immediately outside it for most of its length, the track only diverging from it at its southern end.

The monument is of national importance for its potential to enhance our knowledge of later prehistoric defensive organisation and settlement. The site forms an important element within the wider later prehistoric context and within the surrounding landscape. The site is well preserved and retains considerable archaeological potential. There is a strong probability of the presence of evidence relating to chronology, building techniques and functional detail.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.

Source: Cadw

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