Mapping the Source of the Amazon

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Searching for the Source

The first published discussion of the source of the Rio Amazonas appears in 1641. Father Cristobal de Acuna's New Discovery of the Great River of the Amazons suggests that rivers in three of the kingdoms within the Viceroyalty of Peru were  possible sources of the Amazon: the Napo in Quito, the Caqueta in New Granada, and the  Maranon in Peru. By the mid-nineteenth century improved maps of the eastern slopes of the  Andes showed the Rio Ucayali to be longer than the above rivers. In the 1930s a Peruvian  Army survey identified the Ucayali's longest tributary, the Tambo-Ene-Apurimac system, as  the source of the Amazon. In 1971 National Geographic writer and photographer Loren  McIntyre used airphotos and map sheets to identify the Hornillos-Challamayo-Lloqueta as  the longest tributary system of the Rio Apurimac. From the summit of Nevado Mismi McIntyre  and Victor Tupa, nomenclature director for Peru's Servicio Geodesico Interamericano,  observed a perennial tarn on the mountain's north slope just above Quebrada Carahuasanta.  Using air photos and maps, Tupa determined the coordinates of the tarn and designated it Laguna McIntyre.

Rio Lloqueta

The Lloqueta lies within the Cadena de condos volcanicos part of the high Puna plateau. While the Andes are dominantly  compressive, this area is characterised by neutral or extensional stresses. Soils within  the valley are primarily alluvium and colluvium originating from late Cretaceous to early  Tertiary volcanic rocks. Vegetation cover is sparse, with only short grasses and mosses  lying near drainage channels. Land use in the Rio Lloqueta basin is seasonal and limited to grazing alpacas and  llamas on the grasses near the quebradas. During the dry season herders occupy six remote  estancias in the basin, and the animals are corralled at the estancias during the night.  The pass above the Lloqueta is used as a trade route between Cailloma, a mining center to  the north, and Lari, a pueblo in the Rio Colca valley.

For more information, please contact:

Andrew K. Johnston
Smithsonian Institution
National Air and Space Museum
Center for Earth and Planetary Studies