 The lower end of the valley joins the Vale of Llangollen, the Eglwyseg River flowing into the River Dee near Pentrefelin.The entire valley has been designated a Site of Special Scientific Interest and Landscape of Special Historic Interest.The upland moors have several Bronze Age burial mounds, and there is evidence of agricultural use of the area from the Bronze Age onwards, with the higher pastures being used for summer grazing and the valleys for winter grazing and as arable land, the latter indicated by remaining lynchets.