Notes on the Climate and Physiography of Southwestern Ecuador

Resumen

T HE coastal region of southwestern Ecuador has attracted considerable attention through the investigations for petroleum lately carried on there under the stimulus of the rapidly increasing development of the rich Peruvian fields of the Paita-Tumbes coastal region immediately to the south.' Apart from commercial possibilities the region might well claim the interest of geographers on account of the peculiar features of its surface configuration. In recent geological times an immense amount of erosion has taken place, resulting in a remarkable sculpture; and the processes can be seen in operation at the present day. The region, however, is one of scant rainfall. Dr. R. C. Murphy has called attention to the existence of a meteorological frontier running across it from north to south to eastward of which rain falls annually, while to the westward truly appreciable quantities fall only at intervals of years (compare Figs. 6 and 7).2 In the Santa Elena Peninsula in an average year rain falls only in the months of January-April, this season being the hottest part of the year, and the amount is negligible, rarely exceeding much more than three inches. It is impossible to explain the existence of such enormous tracts of denuded land surface by assuming only the erosion of a succession of normal rainy seasons. The normal regime, however, is interrupted by the periodic occurrence of exceptionally wet seasons. The extraordinary rains and floods of 1925 and 1926 that swept the arid west coast from Ecuador to Chile are fresh in the memory (Fig. 2). The events of 1925 have been vividly described by Dr. Murphy.3 Though such rainy years are of irregular periodicity, they have none the less left evidence of their existence in the devastating results of superficial denudation. There is little doubt that most of post-Quaternary earth sculpture, such, for example, as erosion remnants, tablazo fringes, inland lagoon areas, badland features, and certain steep V-shaped