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. It comprises the Tywi Lineament, Pontesford Lineament and Church Stretton Fault Zone. The southern margin of the fault 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 Church Stretton Fault component of the system is deemed to form the
terrane boundary between the
Cymru Terrane to its northwest and the
Wrekin Terrane to its southeast.