This page is taken from Album noir no. 23, dedicated to archaeological discoveries in the Somme. The drawing, by Édouard Collomb, reproduces in minute detail the strata studied during the excavations that he carried out with Louis Lartet. Like Jacques Boucher de Perthes, Louis Lartet, a correspondent of the Commission de Topographie des Gaules, was very interested in the subject of human fossils. By adopting the principles of stratigraphy, in the 1860s, he was able to determine the chronology of human occupation and provide proof that man had existed alongside extinct animal species.