The wildest stretch of the Borders coast lies between Fast Castle and St Abbs Head – where steep cliffs of greywacke sandstone plunge to the North Sea, fringed by headlands and rocky beaches. From the cliff top, if the conditions are right, we can descend to a remote beach for a close-up view of the rhythmic layering formed on the floor of a long-lost ocean.

THE ROCKS: Layers of greywacke sandstone, originally formed on the floor of the Iapetus Ocean, have been crumpled during the Caledonian Orogeny as the Iapetus Ocean closed, and are now often found tilted at a high angle from the horizontal. From the cliff tops we can appreciate how these layers are laid in repeating sequences, reflecting the processes that formed them. And as we contemplate the modern North Sea we can speculate about what was happening on a sea bed long ago in a long lost ocean.

THE WALK: This is short but strenuous walk on tracks, steep grassy slopes and bouldery beach. We’ll follow farm tracks from Dowlaw Farm southwards, and then a rough path along the cliff tops to a great viewpoint where it is possible to descend to the remote beach. Return along the waymarked path to Dowlaw Farm. Total walking distance about 6 km. I have classified this as an an adventurous walk: involving walking along rocky beaches, clambering over rocks and steep climbs. We will descend and climb steep slopes, with the potential to slip or fall on wet grass and loose gravel. It may be wet, windy or cold. Come equipped with strong footwear with a good tread and waterproof clothing.

MEETING POINT & ROUTE: At the car park beside Dowlaw Farm. Take the A1 to just south of Cockburnspath, and turn east onto the A1107. A few miles south of the junction, at the top of the hill, take the left turn signposted to Dowlaw. Follow this minor road down to the farm, the car park is on the left before the farm buildings. Grid reference NT855701 | Nearest Postcode: TD14 5TY | What3Words: economics.humans.pictured.