Читать книгу Walking on the Gower. 30 walks exploring the AONB peninsula in South Wales онлайн

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These deposits are followed by massive beds of sandstone, known commonly to South Wales miners as the Farewell Rock, as they knew that there were no more workable coal bands once they had struck this distinctive geological marker.

Boulders of Devonian quartz conglomerate on Rhossili Down (Walks 17–22)

The sedimentary layers of rock that form both Gower and the South Wales coalfield were folded to form a massive syncline some 280 million years ago, as a result of plate collisions further south that formed the super-continent Pangea. The older Devonian rocks have been exposed through erosion in the west and north of Gower, and Carboniferous limestone disappears beneath the Coal Measures to the north-east. There is also a series of tight folds that begins on the peninsula and continues under the Bristol Channel and into Devon.

Looking west over Ram’s Grove, showing the inclined limestone beds of the cliffs (Walks 16–17 and 21)

The last major episodes to affect Gower were the Ice Ages, occurring during the last two million years of Earth history. During the Ipswichian interglacial period, around 130,000 to 120,000 years ago, the melting ice caused sea levels to rise to 6-9m above the present level. Subsequent falls in sea level left behind raised platforms, or raised beaches, containing beach deposits cemented with calcium carbonate. Where the beach deposit contains limpet shells among the rounded limestone fragments and sand it is known as the Patella raised beach. Many of the coastal caves open onto the platform of these beaches and it is likely that the caves were enlarged by wave action when they were at sea level.