In the second half of the 19th century, territorial states began to establish governmental geological surveys in order to produce large-scale detailed geological maps on the basis of military topographic map series. Especially the mining administrations were highly interested. In Prussia, Ernst Beyrich already submitted a mapping program 1:25,000 in 1866, and in 1873 he was appointed head of the newly founded Prussian Geological Survey. In the Kingdom of Saxony, Hermann Credner was charged with the "Geognostische Landesuntersuchung" in 1872. Under his direction, 123 map sheets were produced by 1895. This made Saxony the first German state to have detailed geological maps covering the whole country. After Prussia and Saxony, other German states followed, e.g. Hesse in 1881, Württemberg in 1903 and Bavaria in 1909. To this day, geological mapping 1:25,000 for Germany has not been completed.
We have digitised and catalogued our entire collection of geological maps 1:25,000, altogether more than 1700 data sets for individual map sheets have been created. Besides the official geological maps, we also included some seam maps, mainly from the Ruhr area, and about 230 sheets with agronomic drilling details. The latter maps were used to evaluate soil conditions and soil quality with respect to its agronomic usability.
As with the topographic map sheets, the cataloguing included an indexing of natural landscapes, rivers and lakes.