Rocks / Wave ripple marks. Penarth.

Penarth beach is a geologists paradise. There is so much variety of structures, and specimens to be found. The Blue Lias rocks of the Jurassic provide a wealth of fossils, some of which I have collected. The older rocks of the Triassic have provided me with lovely specimens of gypsum, including "Satin spar" var. This particular rock specimen lying on the beach caught my attention. It is from the younger Lilstock formation of the Triassic, and is simply a very crisp wave ripple. The pale mudstone was probably laid down in a shallow sea or lagoon. The ripples are obvious, but the small sharply defined deposits on the surface are a mystery.

A To Z Of Rocks...

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