The Old Red Sandstone occurs in Gower in several inliers which form hills rising above the undulating plateau of Carboniferous Limestone. The chief are Cefn-y-bryn (548 feet) in mid-Gower, Llanmadog Hill (609 feet), the westerly extension of Cefn-y-bryn in north-west Gower, and Rhosilli Down (633 feet) in the extreme west of Gower.