The odd one out in this row of rocks is a piece of Devonian Upper Old Red Sandstone Conglomerate. This outcrops nearby on the top of Rhossili Down. Water-worn pebble, cobble, and boulder-sized segments lie on Rhossili beach below. They may have been shattered from the exposed bedrock by freeze-thaw processes in the inter-glacial periods.
Jessica's Nature Blog 
Beautiful! So varied in colour and texture.
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