“ During twenty years he laboured at the preparation of a geological map of Belgium (1849) . He spared no pains to make his work as complete as possible, examining on foot almost every area of importance in the country. Journeying to the more southern parts of Europe, he investigated the shores of the Bosphorus, the mountains of Spain and other tracts, and gradually gathered materials for a geological map of Europe: a work of high merit which was “one of the first serious attempts to establish on a larger scale the geological correlation of the various countries of Europe.” ”