sentences:  Triassic sandstones form much of the coast between Barry and Penarth and extend eastwards along the Monmouthshire coast to the English border at Chepstow.They also occur more sporadically further west between Ogmore-by-Sea and Kenfig.There are very localized occurrences of Triassic material in Gower and south Pembrokeshire, much of it breccia-fill of fissures in underlying Carboniferous Limestone.