Geological Maps and Data Gaps Assessment: The Key factors for a Solid Geological Background

In 2007, the INSPIRE Directive became a catalyst for re-examining fundamental geological data represented on maps. A major milestone was the OneGeology-Europe project (2008–2010), which for the first time approached 1:1,000,000-scale geological maps as structured datasets. With the involvement of nearly all EuroGeoSurveys member surveys, GeoSciML, the OGC standard for geological data exchange, was adopted and tested, providing feedback that helped consolidate the standard. In parallel, datasets were documented using metadata compliant with ISO 19115 and the INSPIRE metadata profile.
These initiatives encouraged geological surveys to intensify efforts towards the development of geological vector maps at larger scales. However, such work is highly time-consuming and labour-intensive, and despite significant progress over the years, substantial challenges and data gaps remain. To address them effectively, gaps need to be identified and assessed to provide a clear basis for coordinated action.  Advances in geoscientific knowledge frequently require renewed field investigations and the revision of existing maps/data sets to improve the accuracy and quality. 
The GSEU project aims to identify gaps not only in terms of missing data, but also with respect to completeness and consistency, the nature of attributes describing geological units, as well as issues of semantic and geometric harmonisation across map series. Such harmonisation challenges often reflect the evolution of scientific knowledge, classification schemes and mapping best practice over time.
A robust foundation, provided by fundamental geological maps ranging from continental-scale overview products such as IGME5000 to highly detailed maps depicting local geological structures, is essential for guiding future research and development. Geological maps form the foundation for a wide range of applied and scientific activities, including mineral resource exploration, geo-energy assessments, groundwater modelling, geoengineering, vulnerability assessments, spatial planning, and subsurface management.
This contribution presents initial assessments of the current state of geological data coverage across Europe and highlights the importance of comprehensive, harmonised and well-structured  geological map databases for emerging applications, including artificial intelligence (AI) and large language models (LLM).
The GSEU project will also provide an organisational, technical and semantic framework for the digitisation, harmonisation and presentation of datasets describing Europe’s fundamental geology at multiple scales.