If you are interested you can download the official geologic maps from the GeoportalNRW of North Rhine-Westphalia in scale 1:100.000 here:
https://www.opengeodata.nrw.de/produkte/geologie/geologie/GK/ISGK100/GK100analog/
The maps are in JPEG format and georeferenced.
Also available in vector-format:
https://www.opengeodata.nrw.de/produkte/geologie/geologie/GK/ISGK100/ISGK100vektor/
Have fun!