The Ceibwr Bay Fault is a WSW-ENE trending fault zone that cuts Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 rocks of the Ashgill Nantmel Mudstones Formation and the Caradoc Dinas Island Formation. The fault is exposed on the south side of Cardigan Bay

Cardigan Bay

Cardigan Bay is a large inlet of the Irish Sea, indenting the west coast of Wales between Bardsey Island, Gwynedd in the north, and Strumble Head, Pembrokeshire at its southern end. It is the largest bay in Wales....

 in Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

 and forms part of the Fishguard-Cardigan Fault Zone. It extends from the coast at Ceibwr Bay

Ceibwr Bay

Ceibwr Bay is a bay on the southside of Cardigan Bay, adjoining the Irish Sea, in Wales.The high landscape at Ceibwr Bay is made up of spectacular cliff folds, part of the Nant Ceibwr valley leading through the village of Moylegrove, originally formed by glacial erosion. The river runs out into...

 at its western end to the coast at Aberporth

Aberporth

Aberporth is a community and small town in Ceredigion on the west coast of Wales. The population was 2,485 in 2001.- Location :The town lies at the southern end of Cardigan Bay about six miles north of Cardigan and ten miles south of New Quay approximately one mile west of the A487, on the...

at its eastern end. The fault zone is thought to have been active as a normal fault throughout the deposition of the Ordovician sequence.