The rocky foundation of the GSEU project: a pan-European machine-readable hierarchical vocabulary to describe the lithology on geological maps and of boreholes.

To understand geological information across political boundaries, harmonisation (semantically and geometrically), is crucial. The GSEU project (Geological Service for Europe) within the EU Horizon Europe programme, addresses this challenge by building a geological framework which encompasses a pan-European data model, a metadata system, methods to visualize 3-D models and hierarchical, machine-readable vocabularies based on existing terminologies.

Building spatial geological databases for the European continent started from 1995 to 2005 with the project of the International Geological Map of Europe and Adjacent Areas (IGME 5000). Later, based on the OneGeology-Europe project vocabularies (2008-2010), the geology data specification of the European INSPIRE Directive became European standard in 2013.

While these past vocabularies are comprehensive, they lack terms to describe large scale geological map information and specific thematic properties. GSEU fills that gap and hierarchical scientific vocabularies for lithology, anthropogenic deposits and lithotectonic units are developed to define the concepts to which geometrical descriptions (lines, polygons, and volumes) can be linked. Custom programming scripts, written in Python and JavaScript help to automatize the data handling and visualisation of the hierarchical relations.

The endeavour faces considerable challenges, such as:

• setting up vocabularies that take into account differing classification which describe the same concept (term),
• coping with obsolete and/or strictly regional terms,
• taking into account multiple hierarchies and
• including genetically related terms, qualifiers and compound names.

The presentation demonstrates the project’s approach to build pan-European lithological vocabularies, its challenges and provides an outlook to the future development.