 Humboldt showed the three zones of coast, mountains, and Amazonia, based on his own observations, but he also drew on existing Spanish sources, particularly Pedro Cieza de León, which he explicitly referred to.The Spanish American scientist Francisco José de Caldas had also measured and observed mountain environments and had earlier come to similar ideas about environmental factors in the distribution of life forms.Humboldt was thus not putting forward something entirely new, but it is argued that his finding is not derivative either.