The “Prussian Geological Survey” was formed in Berlin on 1st January, 1873. This was the final step in a development which started at the very beginning of the science of geology. It soon became apparent that the best way to present the geological observations made in the field was to have them printed on maps, which. could easily be re-studied and corrected by subsequent surveyors. Besides this the collection of geological observations forms the base for the application of geology in mining and for other economic purposes. Geological maps soon proved to be indispensable.