How understanding past landscapes might inform present-day site investigations: a case study from Dogger Bank, southern central North Sea

The integration of geophysical and geotechnical datasets acquired during a site survey for the Dogger Bank wind farm has enabled a new litho- and seismo-stratigraphy to be established. Although previously believed to be a relatively simple “layer-cake”, the data reveal that the sedimentary sequence within the foundation zone includes a complex series of buried landscapes with implications for both foundation siting and design. The most significant is a Weichselian glacially derived landscape dominated by a large thrust-block moraine complex buried beneath a thin Holocene sequence. This glacial landscape profoundly affects the structure and physical properties of sediments within the foundation zone due to locally intense glaciotectonic deformation and the occurrence of sub-aerially desiccated horizons recording fluctuating palaeo-climatic conditions. Understanding these landscapes, coupled with the geophysical and geotechnical data, enables the development of a predictive “geo-model” that may be used to target areas of uncertainty, reducing the requirement for boreholes (over Cone Penetration Tests) at every potential foundation location.