Cwm yr Abbey Stream Section
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Geology & landscape
Landscape processes: Glacial
Description
Description An outstanding Arenig faunal and stratigraphic locality. One of the key Carmarthen localities yielding well preserved trilobite faunas, in contrast to the normal situation where fauna is either sparse or greatly deformed by tectonism. Its common olenid trilobite faunas differ from other Arenig faunas in Wales and compare most closely with Arenig forms from Spitzbergen. This is the best section in the well known 'Peltura punctata Beds', now in part the Cwm yr Abbey Member of the Carmarthen Formation, with abundant Porterfieldia punctata. A key exposure in studies of trilobite faunas, their distribution and ecology. In layman's terms, the interest of this site may be expressed more simply, and such a statement is provided below. This should not be taken as definitive and further information as to details of the interest can be obtained from the Nature Conservancy Council. Cwm yr Abbey is one of the few localities in South Wales which has yielded well-preserved fossil specimens of a now extinct group of arthropods, known as trilobites. The rocks from which these fossil remains have been described are of considerable antiquity and since their deposition in deep water marine conditions some 500 million years ago they have been subjected to a great deal of folding and faulting. At most locations in South Wales these movements within the earth's crust have tended to destroy or deform the remains of the trilobite fossils, so Cwm yr Abbey assumes particular importance as a rare source of well-preserved specimens. Also of particular note is the fact that one of the trilobite forms described from Cwm yr Abbey shows great similarity to specimens described from Spitzbergen.