Llama distinguished by the inhabitants of South America are recognized as distinct species, though with difficulties in defining their distinctive characteristics. These are: The llama and alpaca are only known in the domestic state, and are variable in size and of many colors, being often white, brown, or piebald. Some are grey or black. The guanaco and vicuña are wild, the former being endangered, and of a nearly uniform light-brown color, passing into white below. They certainly differ from each other, the vicuña being smaller, more slender in its proportions, and having a shorter head than the guanaco. The vicuña lives
Peru–Chile Trench convergent boundary, where the eastern edge of the oceanic Nazca Plate is being subducted beneath the continental South American Plate. Two seamount ridges within the Nazca Plate enter the subduction zone along this trench: the Nazca Ridge and the Juan Fernández Ridge. From the Chile Triple Junction to Juan Fernández Ridge the trench is filled with 2.0–2.5 km of sediments, creating a flat bottom topography. Sediments are mainly turbidites interspersed with oceanic deposits of clay, volcanic ash, and siliceous ooze. The Peru–Chile Trench, the forearc and the western edge of the central Andean plateau (Altiplano), delineate the dramatic "Bolivian Orocline"