Note 16 — Chapter III

In the preface to his “Florula Atacamensis,” Dr. Philippi, who has explored this region more thoroughly than any other traveller, states that on the range of coast hills between the Pan de Azucar (lat. 26° 8′ south) and Miguel Diaz (lat. 24° 36′) the fogs, called in Peru garua, or garruga, deposit during a great part of the year some moisture which occasionally takes the form of fine rain, such as is familiarly known to occur on the hills near Lima. He remarks as singular the fact that the same phenomenon is not observed on the coast north or south of those limits. From more recent observations, it would appear that this is not strictly true as regards the higher coast hills near Coquimbo, but it seems to hold as regards the tract of coast to the northward, between the neighbourhood of Taltal and that of Iquique, a distance of about four degrees of latitude. It may be that the coast hills are lower here than further south, and that as the desert region inland rises very gradually, and has a higher temperature inland than near the coast, the formation of fog is prevented. Whatever be the cause, the absence of fog would go far to account for the utter sterility of this region.