Sinkhole closes road on Gower Peninsula in South Wales.

A road on the Gower Peninsula in South Wales has been closed after a sinkhole was discovered beneath its surface on Wednesday 30 September 2020. Engineers from Swansea Council attended the site after the south Gower Road near the turnoff for Oxwich after a dip was observed in the road, and discovered a void beneath the road described as being 'as large as three terraced houses'. The closure of the road is likely to have an adverse impact on local businesses which are already suffering a sharp downturn in trade due to the Covid-19 epidemic, although one business owner has observed that if they were going to be forced to close due to a geological problem, this was probably a better time to do it than when they were trading at full capacity,

 

A road on the Gower Peninsula in South Wales closed after the discovery of an underground sinkhole. Robert Melen/Wales Online.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.

 

Typical sinkhole formation processes. Southwest Florida Water Management District.

The Gower Peninsula is known to be prone to sinkholes, although these generally occur on farmland. The peninsula is essentially composed of a series of faulted and folded Devonian-Carboniferous rocks that were deformed during the collision of the ancient continents of Avalonia and Laurentia. The majority of these rocks are Carboniferous limestones easily eroded by water percolating through them, leading to the appearance of sinkholes.

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Tourists warned to keep away from landslide on Gower Peninsula.

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.

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Rock Carving on the Gower Peninsula; Britain's oldest art?

On Tuesday this week (26 July 2011) Bristol University announced the discovery of a carving of a speared reindeer in a cave on the Gower Peninsula. It is thought the carving could be over 14 000 years old and is possibly Britain's oldest known art.

The Gower Cave Carving.

The carving was discovered in September 2010 by Dr George Nash of the university's Department of Archaeology and Anthropology in an as yet undisclosed location in a cave on the peninsula. It is located in a very tight niche, where it is thought the artist would only have been able to use their right hand. The cave was already a known archaeological sight; in the 1950s researchers from the University of Cambridge found several hundred flint tools there, which were dated to 12 000-14 000 BC (i.e. 14 000 - 16 000 years ago).

The Gower Peninsula is also the location of Europe's oldest known ceremonial burial, the Red Lady of Paviland (actually a man), discovered in Goats's Hill Cave in 1823 by the Rev. William Buckland, the leading geologist and palaeontologist of the day (and inventor of the post-it note). At the time the skeleton, which was dyed red with ochre, was thought to be a Romano-British woman, but since discovered to be the skeleton of a young (at most 21 years old) man, dating from approximately 33 000 years ago.

The Red Lady of Paviland, now on display in the National Museum of Cardiff.

Cave paintings are not well known in the UK, but they have also been found in the Creswell Crags on the Nottinghamshire/Derbyshire border. The Creswell Crags caves appear to have been occupied on and off since about 43 000 BC, but the cave art is thought to be between 13 000 and 15 000 years old, so the Gower Peninsula claim for the oldest art is a a bit dubious. The Creswell Crags art is much more extensive with a number of carvings of animals and birds. They are also the most northerly cave paintings in Europe.

Bird carving from Creswell Crags.

Whichever of these is the older, the finds are important for what they tell us than because either one is the oldest; science is more than just a competition. Between 18 000 and 10 000 years ago Britain was suffering the most severe glaciation of the Devensian Ice Age, though this was not as severe as some previous ice ages, and did leave both the English Midlands and the South Wales coast free of permanent glaciation. Between 12 900 and 11 500 years ago a period called the Younger Dryas was causing particularly cold and dry conditions. It is notable that both the Gower and Creswell Crags art seem to pre-date this; the Younger Dyas may have been to severe for the artists, leading to a stop in British cave art soon after it started.

Despite Britain having been the subject of palaeoanthropological investigation longer than any other country, there is clearly still much to be found here.

See also: Out of Africa(?)