Ancient Monuments

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Cored Gwyrfai Fish Weir

A Scheduled Monument in Bontnewydd, Gwynedd

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Latitude: 53.123 / 53°7'22"N

Longitude: -4.3152 / 4°18'54"W

OS Eastings: 245172

OS Northings: 360934

OS Grid: SH451609

Mapcode National: GBR 5G.786Z

Mapcode Global: WH43D.PRBP

Entry Name: Cored Gwyrfai Fish Weir

Scheduled Date: 19 November 2002

Source: Cadw

Source ID: 3905

Cadw Legacy ID: CN334

Schedule Class: Agriculture and Subsistence

Category: Fish weir

Period: Medieval

County: Gwynedd

Community: Bontnewydd

Traditional County: Caernarfonshire


The monument consists of the well preserved remains of a fish weir, dating to the medieval period. A fish weir is usually characterised by a foundation of stone topped with a fence or row of stakes, often with nets attached forming an enclosure within a river or harbour and used for catching, or holding, fish. The monument comprises a rectilinear weir defined by spread banks of stone some 4.0m wide and 0.5m high. The inner wall runs from a promontory at 90 degrees to the shore and is some 120m long. Wooden stakes 10 to 15cm in diameter are clearly visible along much of its length. The outer wall runs to the south at a right angle and is some 150m in length. A substantial spur, 100m in length, turns back to the shore at 45 degrees from the southern end of the outer arm. The weir is referred to in letters patent of Edward IV (1461-1483).

The monument is of national importance for its potential to enhance our knowledge of medieval maritime agricultural practices. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits, including preserved wood. The structure itself may be expected to contain archaeological information concerning chronology and building techniques.

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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