[en] Duke A. K. Giedraitis (1848-1909)-a geologist with a renowned professional career, evidenced by his extensive inquiry reports and publications in German, Polish, and Russian (Duke..., 2023). He is well known in Lithuanian and neighbouring countries' scientific history. A. K. Giedraitis created the first geological map of such a large region by international standards, well understood the characteristics of Quaternary deposits, and took at that time an audacious position that previously the area had been covered by two or three glaciations. A standard label and an authorized stratigraphic chart, as well as his observations were used to create the M 1 : 420 000 geological map. A. K. Giedraitis's summary publication with the map, however, did not appear until 1895 (Гедройц, 1895). The objects of his investigations were relief, outcrops, springs, boreholes, and mines. All of them have undergone different changes over time. Some outcrops significant for Quaternary geology have been destroyed or overgrown with trees, or entered the Cultural Heritage System, and others have become stratigraphic standards, etc.