Ancient Monuments

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Coed Mor Fish Weir

A Scheduled Monument in Llanfair Pwllgwyngyll, Isle of Anglesey (Ynys Môn)

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Latitude: 53.2188 / 53°13'7"N

Longitude: -4.1842 / 4°11'3"W

OS Eastings: 254260

OS Northings: 371310

OS Grid: SH542713

Mapcode National: GBR 5M.1B17

Mapcode Global: WH546.PCQ7

Entry Name: Coed Mor Fish Weir

Scheduled Date: 31 October 2002

Source: Cadw

Source ID: 3898

Cadw Legacy ID: AN138

Schedule Class: Maritime

Category: Fish weir

Period: Post Medieval/Modern

County: Isle of Anglesey (Ynys Môn)

Community: Llanfair Pwllgwyngyll

Built-Up Area: Llanfair Pwllgwyngyll

Traditional County: Anglesey


The monument consists of the remains of an impressive and well-preserved fish weir, dating to the medieval or post-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 Coed Môr Weir is defined by well-built, dry-stone walls incorporating modified natural features. The weir walls stand to a maximum height of approximately 3m and are 1.2 to 1.5m in width. The main wall runs parallel to the shore from a small island for 100m in a north-easterly direction. The north-eastern end is ruinous but turns back to the shore and forms a sluice. This ruinous wall incorporates a rocky outcrop that serves to trap the fish in a natural channel running parallel to the main weir wall.

The monument is of national importance for its potential to enhance our knowledge of medieval or post-medieval maritime agricultural practices. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. 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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