In the first decades of the ninteenth century, the country was visited by numerous foreign naturalists who travelled through the country on reconnaissance trips. Among them, Alcide d’Orbigny and Charles Darwin stood out for their pioneering observations and descriptions. Alcide d’Orbigny was sent by the Muséum d’Histoire Naturelle in Paris and after several years of stay in the southern sector of South America, he compiled a colossal work published in Paris. His contributions were mainly devoted to the Cenozoic deposits and the study of their abundant fauna. Charles Darwin carried out his studies along the Atlantic coast and made a complete crossing of the Argentine-Chilean Andes that was made known to the Geological Society of London. His monumental contribution in his book Geological Observations in South America remains a milestone in the understanding of the geological history of this region. These observations were fundamental for the development of his theory on the evolution of species, as he acknowledges was based on what he learned in those years of study in the visited region.