New Geological Map of Offshore Anglesey Released

New Geological Map of Offshore Anglesey Released

The British Geological Survey (BGS) has released a new fine-scale digital map featuring the seabed geology of offshore Anglesey. The island (in Welsh known as Ynys Môn) follows the Bristol Channel as the second in a series of new fine-scale maps that contain combined bedrock, sediment, bedrock structure and seabed geomorphology data.

The maps are based on data produced by the UK Civil Hydrography Programme of the Maritime and Coastguard Agency, which includes bathymetry data, backscatter imagery, grab samples and other existing data sets such as seismic, sediment texture sheets and existing 1:250,000-scale geological maps.

Patchwork of Bedrock and Glacial Deposits

These new resources provide important evidence for policymakers and decision-makers, who need to consider the increasing demands being placed on the marine environment from recreation, marine conservation and protection, fishing and resources (e.g. aggregates). The data may be of particular interest to developers of tidal stream energy devices wanting to deploy technology and infrastructure to create renewable energy and generate clean, low-carbon electricity, making Anglesey a hub for marine energy.

Priority areas currently being mapped also include Yorkshire and East Anglia, with other areas being added as the fine-scale mapping programme progresses.

Seafloor bathymetry near Anglesey. Bathymetry data acquired by MCA. (Crown Copyright)

The seabed substrate around Anglesey forms a fascinating patchwork of bedrock, glacial deposits and more recent marine sediments. Remarkably well-preserved suites of drumlins can be seen on the sea floor in this area; these were moulded under the last ice sheet as it flowed towards the southwest. When the glacier margin retreated, icebergs began to break off, ploughing grooves that can now be seen on the seabed. Under modern marine conditions, strong currents have produced sand waves that can migrate across parts of the seafloor.

The maps are available from BGS under the fine-scale maps section of the Offshore GeoIndex and are designed to be viewed at 1:10,000 scale or offline as downloadable shapefiles.

Extent of the new Anglesey seabed geology map. Contains data acquired by the MCA and by Defra. (Crown copyright)
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