Carte des Etats-Unis de l'Amérique-Nord : pour servir aux observations géologiqueir

Geologic maps originated in Europe during the first half of the 18th century, but it wasn’t until the 19th century that they were more frequently produced. American geologists, following European advancements, were also producing maps. William Maclure ̶ Scottish-born but based in the United States ̶ was a pioneer in the field of American geology. His first map on the subject was issued in 1809. The 1811 French edition of the map is displayed here. Using color, Maclure indicates different rock units according to their ages over large swaths of the country, although the map lacks a legend and specific details.
Courtesy of Boston Public Library