Here is a particularly interesting pebble that I photographed from various angles on the beach at Budleigh Salterton in Devon on the Jurassic Coast World Heritage Site in the U.K. I am not exactly sure what it is but it in all probability came from the pebble beds in the nearby cliffs that were laid down in the Triassic period. The Triassic period lasted from 225 to 180 million years ago. The pebbles themselves are mainly quartzite and were brought to this Devon location by a large river flowing out of a mountainous region in France. These French mountains, and therefore the pebbles derived from them, were composed of rock laid down in the much earlier Ordovician period which lasted from 500 to 440 million years ago. So the sediments of which the pebbles are composed may actually be twice as old as the pebble beds in which they are found.
The patterns and layers revealed in the pebble are fascinating. The ‘glassy’ nature of the stone and the black and pink coloration make me think this stone may have been tourmalinized – but I am open to correction.
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