The Austrian Geological Survey (GBA) has released a thesaurus about their own domain. The main driving factor for institutions like the GBA to invest in thesaurus and taxonomy projects, is the increasing need for a uniform description of their data. The idea is that this enhances value and reusability of their products for their stakeholders. The Thesaurus of the Geological Survey of Austria is a bilingual (de/en) controlled vocabulary for the semantic harmonisation of geoscientific map-based geodata. Currently there are four thematic subjects available :lithologygeologic timescalegeologic unitstectonic units & classification.