Scheduled MonumentsWalesGorad Ddu Fish Weir
Post Medieval · Fish Weir

Gorad Ddu Fish Weir

Anglesey, Wales
Cadw SAM AN139
Period
Post Medieval
Site type
Fish Weir
Broad class
Maritime
Nation
Wales
The designation
Reference
Cadw SAM AN139
Authority
Cadw
Designated
2002-10-31
Boundary

Scheduled area

© Mapbox · © OpenStreetMap contributors · Boundary data © Cadw

Overview

History & significance

Gorad Ddu Fish Weir is a post-medieval fish weir situated in Wales and protected as a scheduled monument by Cadw under reference AN139. Fish weirs of this period represent sophisticated exploitation of river systems, constructed to trap and direct migrating fish into holding areas where they could be captured for food or commercial sale. The structure would have comprised stone or wooden barriers strategically placed across a watercourse to intercept fish passage.

The weir sits upon ancient bedrock composed of hornblende schist, a metamorphic rock formed during the Neoproterozoic period over 540 million years ago. This resistant stone would have provided both the foundation and likely much of the building material for the weir's construction, as local stone was the standard practice in post-medieval Wales. Such geology shaped not only the monument's physical form but also the character of the surrounding landscape and water systems.

The survival of Gorad Ddu as an identifiable archaeological feature reflects both the durability of its stone construction and the stable hydrology of its location. Post-medieval fish weirs remain important evidence for understanding historical fishing practices, water management and riparian economics in Welsh communities, illustrating how communities adapted permanent structures to harness natural resources from flowing waters.

Gorad Ddu Fish Weir is a scheduled monument protected by Cadw under reference AN139. View the official record →

About this monument

Questions & answers

What is Gorad Ddu Fish Weir?

Gorad Ddu Fish Weir is a post-medieval fish weir situated in Wales and protected as a scheduled monument by Cadw under reference AN139.

What period does Gorad Ddu Fish Weir date from?

Gorad Ddu Fish Weir dates from the post medieval period, and is classified as a fish weir. It is one of over 32,000 scheduled monuments protected across the UK.

Who is responsible for protecting Gorad Ddu Fish Weir?

Gorad Ddu Fish Weir is a Scheduled Ancient Monument, legally protected by Cadw — the body responsible for designating and safeguarding heritage sites in Wales. The official designation reference is AN139.

What other scheduled monuments are near Gorad Ddu Fish Weir?

Several scheduled monuments lie within 10 km, including Settlement NW of Waen Rhythallt (7.5 km), Hut Group Near Tan-y-Coed Pont Rhythallt (7.9 km), Hut Group and Enclosure Near Cae Cerrig (8 km).

Unlimited access

Everything a full report reveals about Gorad Ddu Fish Weir

This page is just one thread. A full Aubrey report pulls together 13 strands of Gorad Ddu Fish Weir's history, each drawn from the record and mapped to the exact spot:

Overview
An interactive map of the location with every monument and battle plotted, and a plain-language history built only from what the record holds.
Monuments
The legally protected scheduled monuments around the location, each with its period, type and significance.
Battlefields
The battles and sieges fought on this ground, mapped and set on a timeline of the wider conflict.
Roman Britain
The Roman roads, forts and towns near here, and the Iron Age people who held the land before Rome arrived.
Civil War
The Civil War fighting, garrisons and recorded militaria in this area, woven into the arc of 1642 to 1651.
Geology
The bedrock beneath the site, its age and rock type, reaching back hundreds of millions of years.
Local Names
What the street and field names around here actually mean, and the history buried inside them.
Historical Maps
Ordnance Survey maps from the 1800s, layered over the location as it stands today.
Literature
The books, county histories, charters and archives that mention this place, quoted with their sources.
Legal
The protected sites nearby and the metal-detecting, access and treasure laws that apply to this ground.
Spotlight
A deep dive into the most remarkable, lesser-known history of the place, traced back to the record.
Target Zones
For detectorists: the most promising ground to search nearby, ranked by confidence, with what to expect.
Timeline
The whole story of the location told era by era, from prehistory to the present day.
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Every location is different. Not every section appears for every place, only what the historical record actually holds turns up in a report.

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The ground beneath

The bedrock under Gorad Ddu Fish Weir

Gorad Ddu Fish Weir stands on Unnamed Metamorphic Rocks, Neoproterozoic, bedrock that formed in the Neoproterozoic. The rock here is hornblende schist.

The wider landscape

Around Gorad Ddu Fish Weir

Bryn Celli DduArchaeological site · ~2.5 miles