A dolerite dyke of Ordovician age intrudes the melange at Trwyn y Gorlech in the north whilst an olivine dolerite dyke of Tertiary age is seen at Cafn Enlli in the southeast .
A dolerite dyke of Ordovician age can be seen in the melange at Trwyn y Gorlech in the north . There is an olivine dolerite dyke of Tertiary age at Cafn Enlli in the southeast .