Is there a database of the geologic/stratigraphic units of France?
The best I have been able to turn up is the paid BD-logs service, which provides standardised lithology for borehole data. Open Geospatial Consortium data all appears to be listed on the Geoservices page, and does not appear to include a lithological database/lexicon. The French Geological Reference Platform does not appear to include a standalone database. The BRGM's list of resources also does not appear to provide pointers to any relevant information. Given that the FRGM is in active development, it seems plausible that this is not in fact a dataset that currently exists.