His leisure time was chiefly devoted to the study of what was afterwards called the Stone Age and antediluvian man, as he expressed it. About the year 1830 he had found, in the gravels of the Somme valley, flints which in his opinion bore evidence of human handiwork; but not until many years afterwards did he make public the important discovery of a worked flint implement with remains of elephant and rhinoceros in the gravels of Menchecourt. This was in 1846.