Students Map the Seafloor // by Gareth Carter

From 24th June to 10th July 2019, two MSc students from the University of Portsmouth’s Engineering Geology degree joined the British Geological Survey’s Marine Geoscience team in the Lyell Centre, Edinburgh, to undertake their thesis projects. 

Lauren Farnworth and Tristan Campbell-Reynolds arranged the placements through Gareth Carter and Emrys Phillips, having expressed an interest in offshore infrastructure planning and installation. The aim was for Lauren and Tristan to undertake preliminary site assessments for different types of offshore infrastructure in an area of the Outer Bristol Channel: one focusing on wind turbine foundations and the other on sub-sea cable route assessments.

In order to do this Lauren and Tristan carried out detailed geomorphological mapping of the seafloor at a scale of 1:10,0000 using multibeam bathymetry data. This approach allowed Lauren and Tristan to identify and map out the potential geological constraints which would impact on the siting of the offshore installations: for example potentially mobile sandwaves and hard bedrock exposed on the seabed. 

Initially, BGS 1:250,000 offshore bedrock and seabed sediment maps were consulted before the students undertook their own analyses and interpretation at a higher resolution. Seabed sediment mapping was conducted using sediment grab and core sample data to understand where sediments of different grain sizes were accumulated as this can affect the foundation design for wind turbines or the approach used for laying cables. The geology concealed beneath the seabed was interpreted based on BGS open access core and borehole logs available from the Offshore GeoIndex, allowing the students to create 3D fence diagrams which show the likely subsurface structure and ground conditions across the proposed sites. 

Lauren and Tristan are using their interpretations of the data to construct conceptual “ground models” which the renewable industry need to proceed into the development phase of any offshore infrastructure. As part of this, Lauren and Tristen were able to tentatively identify areas of their respective sites that would or would not be suitable for certain infrastructure types based on the surface and subsurface geology, and make recommendations on future Site Investigation and Survey works required to increase the resolution of the ground models.

Aside from the experience of carrying out a site investigation desk study, Lauren and Tristan also became part of the BGS marine geoscience team and benefitted from talking to a range of scientists and technical experts who work at the BGS.

Of their experiences, the students said:
The BGS open data was very useful as it allowed me to access shallow cores, boreholes, seabed grabs, seismic reflections and the 1:250 000 scale offshore geological maps, which aided me in producing my 1:10k scale map.
Lauren Farnworth 
Lauren's map (in progress), showing the geomorphology, superficial and bedrock geology of part of the Bristol channel.

So much of the data that BGS provide is taken for granted by us students and after seeing the enormous amount of work that goes into developing and maintaining the public resources like offshore geoindex and the BGS websites, I certainly have a new found respect for the hard work the whole team puts in to make our lives easier.  
Tristan Campbell-Reynolds
The BGS is the MEDIN Data Archive Centre (DAC) for marine geology, geophysics and backscatter. If you are interested in using the open access marine data, see our marine data webpages and please contact for more info. Marine data can be downloaded under an Open Government Licence in various formats (e.g. GIS layers, seabed particle size data, or pdf core logs) using the “Clip & Download” tool on the Offshore Geoindex. A Web Map Service is also available. You can also deposit data with us.

Bathymetry data held by the UK Hydrographic Office (UKHO) can be accessed from the Admiralty Marine Data Portal. Data and reports from the offshore renewable and marine aggregate industries can be accessed from The Crown Estate’s Marine Data Exchange.