A small basket of Jurassic Coast pebbles. It includes a small heart urchin fossil from Lyme Regis in the middle, and a blue-grey limestone pebble with a white heart-shaped mark from Charmouth. The holes in some of the stones are caused by burrowing marine animals: the large holes, like the ones in the pebble top left, are probably made by a bivalved mollusc called the Flask Shell, Gastrochaena dubia Pennant. The smaller borings in other pebbles are most likely the result of attached mud-tube-living marine worms like Polydora ciliata (Johnston) in which the acidic waste products dissolve the stone.
The other pebbles include three mottled yellow, white, grey irregular-shaped flint nodules; a pebble with a fossil gastropod; and two strangely patterned stones with reddish designs reminiscent of some of the Chesil Cove pebbles that I featured in an earlier post. I think they are Triassic quartzite pebbles from Budleigh Salterton in Devon and the coloured markings are caused by oxidising iron within the stone.
Revision of a post first published 17 June 2009
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