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The work at Caldicot Castle and elsewhere suggests the innundation of the sea in the Severn, and indeed across the south of Britain, was in part due to sedimentation changes at the coast dependent on climate change*. Long term climate change in the North Atlantic follows a broadly 1500 year cycle*. However, actual temperature proxies show that the picture is more complex. Temperature records extracted from cave features growing over the period in Ireland show a broad cooling from ~5400 to 1500BCE, then rising temperatures to 600BCE which begin to fall into the Dark Ages Cold Period (Note) after 0CE*. To a degree, this matches the picture in terms of tidal influence at Caldicot Castle (Note). While higher temperatures in the North Atlantic therefore seem to match with a higher tidal influence in the Severn, suggesting tidal conditions lasted through the Roman period and fell into the Dark Ages, the relationship between climate, landuse and sedimentation is certainly not this clear cut.