Maps of the geology of Eastern Europe reflect the historic political instability of the region. Before the First World War, empires prevailed – Austrian /Austro-Hungarian, Russian, German. Within these were provinces or regions, whose names have been lost as they were subsumed and/or divided by subsequent nation states that followed the break-up of empires. With the drastic shifts of population and changes of languages and sometimes of alphabets, place names on early maps are often difficult to locate in the present.
Bukovina was the most eastern province of the Austro-Hungarian empire and is now divided between Romania and the Ukraine.
Kurland was a German region including Lithuania and part of Poland. The map extends to Latvia, Estonia.
In Silesia, coal was of immense economic interest. The area of this map straddled the frontier between the Russian Poland and the Austrian Empire.
European Russia was opening up to railway development and exploration to bring valuable resources to western factories.
Baku at the eastern tip of the Caucasus region provided the earliest oil millionaire in Europe.
Romania's geology was explored as part of eastward expansion. The map shown was produced with Hungarian assistance and printed in Berlin.
Poland re-emerged as a nation state after WW1 and produced geological maps in its own name.
Following the Second World War, the Iron Curtain created a new division containing Eastern Europe and the ensuing Cold War continued for four decades. During this period, national maps and map sets were generated to provide geological overviews often for western consumption at international congresses
For post congress field trips, larger scale route corridor maps and regional maps provided more detail such as this Bulgarian excursion series.
For information on the geological maps of Eastern Europe, predating the above, I recommend Early Geological Maps of Europe; Central Europe 1750-1840, ISBN 978-3-319-22487-9, published in 2016. For a full review see the History of Geology Group Newsletter no. 60 (PDF, on p. 23)