Peat deposits located in the intertidal zone around mean low water, west of Dinas Dinlle coastal hillfort.

A small exposure was recorded by Gwynedd Archaeological Trust in their North Wales Intertidal Peat Survey 2001-2002 (Smith, G, Davidson, A and Kennedy, J, 2002):

The peat was a very limited exposure of a few metres square although more extensive exposures have been seen in the past. It was quite smooth surfaced with no evident woody remains. The peat was about 0.25m deep and overlying grey clayey silt.

The western, sea-ward edge was exposed and eroded but the land-ward side could be seen to run back beneath the sand higher up the beach so more of the peat must survive elsewhere. Some of this was exposed by digging off the sand cover and this revealed a piece of horizontal round-wood about 10cm dia., probably a root. This was sampled for identification and possible dating. Samples were also taken of the peat and the underlying clay.

In June 2018, the EU-funded CHERISH project (RCAHMW) recorded with GNSS the precise location of a small, exposed area of peat centred on SH 43529 56228, just below mean low water. This comprised two north facing erosion faces, 5.57m and 2.3m in length, behind which the peat was exposed for a few metres to the south, before running beneath the sand and shingle beach. The peat was around 0.3m thick overlying grey silty clay.

On 19 September 2020, a core sample was taken by CHERISH (Aberystwyth University) in the area where peat had been observed in June 2018. The core was extracted at SH 43519 56231 (height at surface -1.424m). On analysis, the peat appeared to be of a fen-type peat (such as Phragmites), 2 radiocarbon dates were obtained.

• UBA-43878: top surface of the peat. 2-sigma age range 5478-5370 BC median cal age 5420 BC (7370 BP) Mesolithic.
• UBA-43879: from the round-wood beneath the peat and above the underlying clay. 2-sigma age range 5618-5480 BC median cal age 5550 BC (7500 BP) Mesolithic.

During CHERISH project work in the area, broken fragments of peat were also observed washed up on the beach following storms.

The peat deposits indicate a brackish-freshwater deltaic environment existed here prior to inundation by the sea. They also help define what was the maximum extent of the eroding glacial mound upon which Dinas Dinlle coastal hillfort sits.

Louise Barker and Patrick Robson, CHERISH Project RCAHMW & Aberystwyth University, May 2020.

CHERISH (Climate, Heritage and Environments of Reefs, Islands and Headlands) is an EU-funded Wales-Ireland project (2017-2023) led by the Royal Commission on the Ancient and Historical Monuments of Wales, in partnership with the Discovery Programme: Centre for Archaeology and Innovation Ireland, Aberystwyth University: Department of Geography and Earth Sciences and Geological Survey, Ireland.  https://cherishproject.eu/en/

Sources:

Bell, M, 2007, Prehistoric Coastal Communities: The Mesolithic in Western Britain, CBA Research Report 149, pg2

Smith, G, Davidson, A and Kennedy, J, 2002, North Wales Intertidal Peat Survey 2001-2002. Gwynedd Archaeological Trust. Report 450.