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Thursday 27 February 2020

Abermawr raised beach -- more exposures after the storms




The main raised beach exposure, including some boulders over 50 cm in diameter.  The exposure is up to 2 m thick and 4 m from edge to edge, and is capped by brecciated slope deposits and then the famous Abermawr "rubble drift"  -- now interpreted as a rearranged or mobilised meltout till madee of far-travelled materials mixed with local slope deposits.

Following the two severe storms within the last fortnight, I think some spray from the highest waves has been reaching the raised beach exposures in the northern cliff section at Abermawr -- about 5m above HWM.  I have not ben able to fix the altitude properly, because the exposures are inaccessible at present.  Anyway, there are now two exposures separated by a gully -- and in all, the beach remnants stretch about 10 m laterally.



The second exposure of the raised beach, which extends for c 6m and rests on an inaccessible  bench or platform on top of a rough bedrock cliff (which is steep and slippery).  The brecciated deposits resting on the beach are of Early and Middle Devensian age, accumulated over a period of maybe 50,000 years.


On this remnant of the raised beach platform we can see clear traces of a smoothed wave-eroded surface below the rock overhang.  It's steeply sloping, and when -- in due course -- it becomes possible to examine the raised beach and its platform at close quarters, it will be interesting to see how this smoothed rock slab relates to everything else......

As indicated in earlier posts, the assumption is that this is a Last Interglacial raised beach capped by a suite of Devensian periglacial and glacial deposits.




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