Tourists have been warned to keep away from the site of a landslide at Oxwich on the Gower Peninsula in South Wales after a number of people were seen exploring the site this week. The landslide occurred on Sunday 6 January 2019, when a number of large rocks, some thought to way in excess of 1000 tonnes, tumbled onto the beach. The site is part of a disused limestone quarry, where rocks from the Oxwich Head Limestone Formation are exposed. These rocks are prone to freeze-thaw fracturing, in which water enters the rocks during rainy conditions, then freezes as the temperature drops. As ice has a higher volume than water, the freezing water expands, forcing the cracks to widen and the rock to split. This typically results in rockfalls when the ice begins to melt, as structural strength provided by the ice is lost and the large cracks cause the rockface to fail.
The scene of a landslide at Oxwich on the Gower Peninsula earlier this month. Wales Online.
Landslides on beaches in the UK are attractive to fossil hunters, as fresh rockfalls often expose new fossil material. The Gower Peninsula has a number of interesting fossil sites, yielding Corals, Brachiopods and other marine fossils, but the rocks of the Oxwich Head Limestone Formation are likely to prove disappointing, as these massive Carboniferous limestones, although originally largely made up of Coral skeletal material, have largely been recrystallised since they were laid down, making fossil material extremely rare in this formation.
Map of the bedrock geology in the area of the Oxwich Bay landslide. BGS.
