Establishing the Austrian General Geological Legend (EAGLe)

In 2024, Geosphere Austria initiated the project EAGLe (Establishing the Austrian General Geological Legend) to develop a harmonized nationwide geological dataset at a scale of 1:50,000 by the end of 2026. The primary objective is the creation of a hierarchically structured general legend by standardizing and harmonising the lithostratigraphic terms that are used in the different map sheets. This work is carried out by regional teams with varying starting conditions: The Quaternary and Neogene teams relied on already existing comprehensive lists, such as general legend only for Quaternary lithogenetic and geomorphological terms and the stratigraphic chart description for the Cenozoic eratherm. On the other hand, for the regions with basement rocks at the surface (such as the Tauern Window and the Bohemian Massif), regional teams faced the additional challenge of establishing coherent concepts for the lithostratigraphic and lithodemic terms in the respective regions. In some cases, legend descriptions —particularly from older maps—are either ambiguous or significantly outdated, yet they represent the only available information for certain geological units. Without field surveys, these entries can only be assigned to very general geological units. A comprehensive revision and mapping of all legend descriptions is therefore not feasible at this stage; consequently, the original legend descriptions will be included in the final dataset to ensure transparency.

The data base for this compilation consists of over 25000 legend descriptions from published geological map sheets at the scale of 1:50,000, added by GeoFAST maps at the same scale (maps compiled from selected archival material without additional fieldwork), as well as regional maps, partly at a scale of 1:25,000. However, the corresponding vector datasets exhibit considerable heterogeneity in both geological content and data structure. In some cases—particularly for older maps—vector data are entirely absent. Therefore, the second major objective is to consolidate these different datasets into a unified structure and to digitize older analogue maps to close existing digital gaps. It should be noted that this initial version will not include any geometric adjustments (e.g., correction of “sheet boundary faults”).

The first version of the integrated dataset, incorporating the preliminary general legend as far as possible, will be published on the Tethys Data Repository (www.tethys.at) by the end of 2026 and will be made publicly accessible via the Geosphere Austria web service (www.maps.geosphere.at). An additional metadata layer will provide information on the quality of the underlying published sources.