A Swiss superintendent of mines, Charpentier made extensive field studies in the Alps. Attending a lecture by the naturalist Ignace Venetz (1788–1859) in 1821, Charpentier was persuaded that Swiss glaciers had once been much more extensive. Using evidence of erratic boulders and moraines to support this idea, he finally managed to overcome the resistance of Agassiz by taking him to visit the Aar Glacier. Agassiz then developed further the theory of a former ice age.