The shallow geology of the southern North Sea and Baltic Sea - relevance for offshore wind

Northern Europe as one of the focus areas for offshore wind energy expansion is dominated by glacial deposits in the shallow sub-seafloor. These glacial deposits originate from several ice advances throughout the Pleistocene and show a significant level of complexity and heterogeneity over short lateral distances. Ground models for the design of wind turbine foundations rely on a successful integration of geophysical, geotechnical and geological data. A good understanding of the geological setting and the expected deposits helps significantly in creating dependable models of the subsurface. Data examples show the typical geological successions for the southern North and Baltic Sea respectively. Significant differences in the two neighbouring basins are varying basement geology, the presence of till units, the nature of glacial incisions and the preservation of interglacial deposits. Geological challenges for foundations such as weak/hard layers, boulders or shallow gas depend on the general setting of the respective site and may be anticipated with a prior knowledge of the geological setting. Thus, a proper understanding of the local geology and the specific challenges of different areas facilitates the planning of geophysical and geotechnical investigations as well as the integration of the resulting data.