Among the many unusual features of the desert coast of northern Peru are the five major beach-ridge sets: Santa (9˚S), Piura (5˚30' S), Colán (5˚S), Chira (4˚50' S), and Tumbes (3˚40’ S). These features of the landscape began forming after 5800 cal yr B.P., initiated by severe El Niño and seismic events. Archaeological remains on the beach-ridge sets of Santa, Colán, and Chira provide evidence of local prehistoric peoples. The extent of prehistoric occupation and utilization of beach ridges varied due to environmental limitations influenced by beach-ridge substrate material, local paleoenvironments, and climate-change events.
Reid, David A., "Peruvian Beach Ridges: Records of Human Activity and Climate Change" (2007). Honors College. 2.