BibliOdyssey’s latest map-related find is Jean-Étienne Guettard’s Atlas et description minéralogiques de la France (1780), digitized and available online at the University of Strasbourg, where, peacay notes, “maps start on page 223 … the full maps at the site are large, around 6 MB each.”

See also this page of French geological maps, most of which either by or after Guettard, also via BibliOdyssey.