The notebooks of mineralogist and petrographer Friedrich Johann Karl Becke (1855-1931) give impressive testimony to the scientific practices at the turn of the century. Moreover, they provide a detailed insight into Becke's working style and depict a disciplined and experimentally adventurous scientist who meticulously documented observations of nature and arrived at new and fundamental conclusions from an objective point of view that were way ahead of his time. Until now, his study books have received little attention. For the first time ever, Margret Hamilton extensively examines the records of Friedrich Johann Becke, drawing a detailed panorama of earth sciences around the year 1900.