Ydw Valley and Fron Road Geological Exposures
Geology & landscape
Mining / Industrial: Quarry · Geological Period: Silurian
Description
Description This is a composite site consisting of five separate exposures. Ydw Valley The four sites here include important sections in strata of the Llandovery Series, here in its type area. These lower Silurian rocks have been the subject of study for more than one hundred and fifty years. Their stratigraphy and shelly faunas have been studied in detail in recent years, and the sections were used to define the Idwian and Fronian stages of the Llandovery, and include the type section for the Goleugoed Formation. These are historically important sections spanning the Rhuddanian and Aeronian stages of the Llandovery Series. Fron Road This locality's old quarry and roadside exposures show rocks of Llandovery age in the historic type area for this division of the Silurian Period. The site includes sections in the Coldbrook, Rhydings, Wormwood and Cerig formations, totalling more than 400 metres (1312 feet) of strata. Marine faunas are dominated by brachiopods, including Eocoelia, and a moderately diverse microflora of acritarchs has been described. The lower boundary of the Telychian Stage of the Llandovery Series has been placed within this sequence. This is a key locality for Silurian stratigraphic studies in the historic type area for the Llandovery Series. Remarks: Part of one of the exposures (Fron Road) is within the Brecon Beacons National Park.