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Portrush West Strand Coastal PeatAntrim
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Summary Full report
Site Type: Coastal section
Site Status: PASSI
District: Coleraine Borough Council
Grid Reference: C855402
Rocks
Rock Age: Quaternary (Holocene)
Interest
Fossil Groups: Plant
Other interest: No data, No Data, beach sand, buried peat, pollen analysis, radiocarbon dating, sand dune

Summary of site:

The beach to the west of Ramore Head in Portrush has attracted scholarly attention for over a century mainly because tree roots and stumps were exposed on the shore and in the sandy cliffs behind. Unfortunately modern beach works, largely the construction of a sea wall in the 1960s, have obscured the geological interest although tree remains can still be seen occasionally when the sea has stripped large quantities of beach sand.

This description employs the earlier scientific literature to recreate a section through the deposits as they were to the 1960s. The deepest deposit exposed was a fine-grained sand, devoid of pebbles and shells, in the form of ridges interpreted as dunes. This was succeeded by a layer of peat over a metre thick containing tree remains. Carbon dates were obtained from the base and top of this peat giving ages of just over 7,000 years and around 6,000 years respectively. The peat in turn was topped by red and yellow laminated beach sands containing pebbles and cobbles in the top layers (and throughout at the south west end of the beach). Above this bed light grey blown sand several metres thick extends inland where it takes the forms of dunes with maximum heights around 15 m. When the Geological Survey of Northern Ireland re-examined the area in the late 1970s they described a section from a borehole put down through the beach north of Castle Erin in 1938. This section commenced with boulder clay topped by 2 m of grey sand, 1.8 m of boulders and sandy clay and 3 m of sand. Above this sand was a peat layer 4.5 m thick. The section was completed to beach level in blown sand considered to be the first bed of dune sand from the historic reconstruction. The history of the site interpreted from the originally described deposits commences with low wind blown ridge dunes. A little over 7,000 years ago, fresh water pools between the dunes evolved into fens and eventually scrubby woodland of alder and birch with reeds colonised this wet surface, the accumulating peat finally overwhelming the sandy ridges. The rising sea level reached its maximum around 5,900 years ago, flooding and killing the scrubby vegetation and covering it with beach sands. As sea level progressively fell, the area began to accumulate blown sand slowly building to the modern dunes. Interpretation of the borehole section would undoubtedly extend events into earlier post-glacial times but no cores survive for inspection. This site is important for its long Holocene (the last 10,000 years) history and retains considerable research interest in the deposits below modern beach level uncovered in the 1938 borehole. Periodic exposures make the site well worth protecting and a programme of borehole investigations is needed to present what could be a complete record of events following glacial retreat.


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