Welsh Borderland Fault System
Encyclopedia
The Welsh Borderland Fault System is a zone of faulting and associated folding
which runs northeastwards through Wales
from Pembrokeshire
through Carmarthenshire
and Powys
into Shropshire
in England
. The southern margin of the System is defined by the Church Stretton Fault and Dulas Valley Fault, amongst others whilst its northern margin is defined by the Garth-Llanwrtyd Fault Belt in Carmarthenshire.
The system was active during the Caledonian Orogeny
and was reactivated during the later Variscan Orogeny
.
Fold (geology)
The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in...
which runs northeastwards through 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...
from Pembrokeshire
Pembrokeshire
Pembrokeshire is a county in the south west of Wales. It borders Carmarthenshire to the east and Ceredigion to the north east. The county town is Haverfordwest where Pembrokeshire County Council is headquartered....
through Carmarthenshire
Carmarthenshire
Carmarthenshire is a unitary authority in the south west of Wales and one of thirteen historic counties. It is the 3rd largest in Wales. Its three largest towns are Llanelli, Carmarthen and Ammanford...
and Powys
Powys
Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...
into Shropshire
Shropshire
Shropshire is a county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. It borders Wales to the west...
in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. The southern margin of the System is defined by the Church Stretton Fault and Dulas Valley Fault, amongst others whilst its northern margin is defined by the Garth-Llanwrtyd Fault Belt in Carmarthenshire.
The system was active during the Caledonian Orogeny
Caledonian orogeny
The Caledonian orogeny is a mountain building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian, roughly...
and was reactivated during the later Variscan Orogeny
Variscan orogeny
The Variscan orogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica and Gondwana to form the supercontinent of Pangaea.-Naming:...
.