 The Old Red Sandstone is a series of red sandstones, marls and conglomerates. It rises as an anticline in the Mendips and appears in the Avon Gorge and at Portishead. Carboniferous Limestone, of marine origin, covers the sandstone and appears in the Avon Gorge and at Weston-super-Mare where it contains volcanic rocks. There are outlying hills at Worlebury, Middle Hope, the Failand Ridge, Broadfields Down, Portishead Down and Wrington Hill.
