The Bronnant Fault is a geological fault affecting the lower
Palaeozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and '' ...
rocks of the counties of
Ceredigion
Ceredigion ( , , ) is a county in the west of Wales, corresponding to the historic county of Cardiganshire. During the second half of the first millennium Ceredigion was a minor kingdom. It has been administered as a county since 1282. Cere ...
and
Pembrokeshire
Pembrokeshire ( ; cy, Sir Benfro ) is a Local government in Wales#Principal areas, county in the South West Wales, south-west of Wales. It is bordered by Carmarthenshire to the east, Ceredigion to the northeast, and the rest by sea. The count ...
in West
Wales
Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...
. The feature is mapped over part of its length as the Bronnant Fault Zone and is closely associated with the
Glandyfi Lineament, a similarly aligned zone of
faulting
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
and
folding
Fold, folding or foldable may refer to:
Arts, entertainment, and media
* ''Fold'' (album), the debut release by Australian rock band Epicure
*Fold (poker), in the game of poker, to discard one's hand and forfeit interest in the current pot
*Above ...
. The rocks of the
Aberystwyth Grits Group
The Aberystwyth Grits Group is a Silurian lithostratigraphic group (a sequence of rock strata) in mid Wales. The name is derived from Aberystwyth in northern Ceredigion where the strata are well exposed in coastal cliffs. The Group comprises the ...
dating from the
Llandovery epoch of the
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
period thicken markedly to the west of the fault suggesting it was active at the time of their deposition. North of
Lledrod
Lledrod is a village and community in Ceredigion, Wales. The village is situated on the A485 road from Llanilar to Tregaron, where it crosses the valley of the River Wyre (Welsh: Afon Wyre). The parish is divided into Lledrod Isaf (Lower Lledrod) ...
its alignment is affected by cross-cutting east–west faults, including the
Ystwyth Fault Zone. Its alignment is sub-parallel to the coast of
Cardigan Bay
Cardigan Bay ( cy, Bae Ceredigion) 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.
Geograp ...
thus curving from a north–south alignment in the north through a northeast–southwest alignment until it merges with broadly east–west aligned faults in northeast Pembrokeshire.
[British Geological Survey 2010 Fishguard. England and Wales sheet 210. Bedrock and superficial deposits. 1:50,000 (Keyworth, Nottingham: BGS)]
See also
*
List of geological faults of Wales
This is a list of the named geological faults affecting the rocks of Wales. See the main article on faults for a fuller treatment of fault types and nomenclature but in brief, the main types are normal faults, reverse faults, thrusts or thrust fa ...
References
Geology of Wales
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