Many years ago, I picked up these wonderfully patterned and coloured pebbles on a beach in Corsica. They remind me of the warm sunny day that I saw the fantastic sight of an entire seashore covered with pebbles just like them.
I have to confess that I know very little about them except that they are extremely beautiful and varied in many ways: geological origin and structure; pattern (plain, spotted, marbled and striped); texture and shape (smooth, rounded or flattened); and colour (yellow, orange, red, black and white). The rocks from which these stones were derived must to be volcanic or igneous in origin. I remember that in Corsica the whole mountainsides are pink and red.
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Jessica's Nature Blog 
I have seen similar, perhaps not quite this colourful, on several beaches from Torquay to Sidmouth. So perhaps Corsica is Triassic too, with some volcanoes thrown in for good measure?
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Yes, some of the pebbles from Corsica do resemble those that can be found on Devon beaches, but their origins are mostly different.
I’m not an expert geologist but my understanding is that the colourful red and orange Triassic rocks found in the UK are basically sedimentary. Sedimentary rocks are accumulations of small particles that were precipitated on land or underwater in successive layers that later became consolidated into hard rock. The Triassic sediments, for example, developed in a hot desert environment that was later subjected to marine or lacustrine inclusions.
On the other hand, the majority of rocks in Corsica are igneous or metamorphic. The island rose from the sea 250 million years ago as a mass of igneous granites. These are mostly volcanic in origin. The main mountain chain that forms the backbone of the island is composed of granite – often very colourful. 50 million years ago further earth movements created massive pressures against the east of the island and these pressures transformed (metamorphosed) the granites to schists.
The pebbles in my pictures were picked up on a beach on the island’s western shore; and many no doubt are igneous rocks that were brought there by rivers flowing downstream from the Spelunca Gorge – which is famous for its red granitic cliff faces.
There are some granite pebbles on Devon and Dorset beaches, too, but these are not Triassic but igneous rocks. They could be from volcanic intrusions into the Devonian sedimentary strata of Cornwall – and have probably moved eastwards along the south coast to Devon by longshore drift from Cornwall.
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I have a collection of these pebbles from Corsica in 2004.Can you remember the name of the beach as we would like to go back.
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Hello, Heather. It is a very long time since my visit but I think I saw these pebbles at Porto on the west coast of the island, south of Calvi.
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