CYNGOR CEFN GWLAD CYMRU
COUNTRYSIDE COUNCIL FOR WALES
SITE OF SPECIAL SCIENTIFIC INTEREST CITATION
YNYS MON FFERAM-UCHAF
National Grid Reference: SH 362867
Site Area: 1 ha
Fferam-uchaf is of special interest for its exposures of Llanvirn (Ordovician) rocks. The site comprises a number of small rock outcrops including a quarry on farmland approximately 1.5km north-east of Llanddeusant.
This is the best locality for Llanvirn rocks in Anglesey, a Series that is otherwise poorly represented in North Wales. Fferam-uchaf shows small but stratigraphically important outcrops, with a diverse fauna, beneath the Caradoc Fferam Ironstone. The shales of the Llanvirn, the uppermost part of the Nantannog Formation, contain stratigraphically diagnostic graptolites together with a shelly fauna of bivalves, brachiopods and trilobites. This is an important site for an understanding of Lower Ordovician palaeogeography and the distribution of its faunas and sediments.