Dating in gwynedd
The Bishop’s Palace, Bangor: Statement of Significance Bangor Bishop’s Palace (Bangor Town Hall) is a grade II listed building.
It was surveyed by the Royal Commission in 1949, and its condition then was only ‘fair’.
Map of Dinas Dinlle showing cliff top positions in 1900, 1917, 19.
Most recently, erosion has been focused at the southern end of the fort where recent (February 2019) mass movement has taken place.
It is set on a hill of glacial drift sediments (specifically a thrust-block moraine) overlooking the sea and Caernarfonshire coastal plain.
The hillfort and Second World War seagull trench on the northern slopes of the fort are protected as Scheduled Monuments by Cadw and the hill is a Site of Special Scientific Interest (SSSI), designated for the importance of the glacial sediments, clearly seen in the exposed sections of till, sand and gravel in the cliff face.
Radiocarbon ages suggests the record extends back around 3,000 years and work is on-going to look at the vegetation and hydrological histories.
The recently published UK Climate Projections (UKCP2018) provides the most up-to-date assessment of how the climate of the UK may change over the 21st century.
The presence of the peat also provides us with a maximum extent of the glacial hill upon which the fort was constructed, and as sea levels flooded this former environment so erosion of the glacial sediments began.
This work has included gathering highly accurate (centimetre and sub-centimetre) 3D data to monitor the eroding cliff edge using techniques such as terrestrial laser scanning and UAV/drone survey.
This will provide an accurate baseline for future monitoring and with analysis of historical documents such as aerial photographs and mapping, will reconstruct as accurately as possible erosion rates over the past 150 years.
More intense rainfall with climate change could increase this erosion, coupled with periods of more intense drought which desiccate the fragile coastal soils leading to wind erosion and the creation of cracks which allow the formation of natural soil pipes under the surface.
High-tech baseline monitoring of the fort: 2017-2021 Dinas Dinlle is a baseline monitoring site for CHERISH.