20 large settlements with monumental architecture, whose origins date to between 3200 and 1800 b.c.e The most intensively researched of these sites are Áspero, at the mouth of the Supe River, and Caral, about 131⁄2 miles upstream from Áspero It was his work at the site of Áspero that in 1975 prompted U.S archaeologist Michael E Moseley to propose a hypothesis conventionally called the “maritime foundations of Andean civilizations” (MFAC) According to the MFAC hypothesis, the initial formation of complex societies in the Andean region took place along the coast and was made possible through the intensive exploitation of maritime resources This, in turn, was made possible largely through the cultivation of cotton, which was used to manufacture the nets needed to harvest the coast’s abundant fish, especially anchovies and sardines Evidence unearthed at Áspero and other sites in the North Chico since the 1970s strongly supports the MFAC hypothesis, though debates continue regarding the origins and characteristics of these societies The site of Áspero presents numerous anomalous features It contains no pottery, only a few maize cobs, and some 17 large earthen mounds, some nearly 16 feet tall The largest structure at the site, a flat-topped pyramid called Huaca de los Ídolos, covers some 16,145 sq feet, upon which, it is hypothesized, Áspero’s elite undertook ritual and ceremonial displays The site also contains some 30 to 37 acres of domestic middens (refuse areas), along with evidence that its residents were continually rebuilding the mounds and other structures This latter characteristic is also apparent at other Pacific coast sites Upriver from Áspero, at the site of Caral, which covers some 150 acres, investigations have revealed some 25 pyramids or mounds, one reaching 82 feet in height and covering some 247,570 sq feet; two large, rounded, sunken ceremonial plazas; arrays of other mounds and platforms; extensive residential complexes; and evidence of long-term sedentary inhabitation Radiocarbon dates indicate that Caral was founded before 2600 b.c.e The same dating procedure applied to other sites in the North Chico indicates that most were founded between 3000 and 1800 b.c.e Middens at Caral and other North Chico sites indicate that maritime resources exploited through cotton cultivation and net manufacture were supplemented by a variety of cultigens, including legumes and squash, and by the gathering of diverse wild foods In addition to Áspero and Caral, the most extensively researched Andes: Neolithic 15 of these sites to date include Piedra Parada, Upaca, Huaricanga, and Porvenir and in the Casma Valley, the sites of Sechín Alto, Cerro Sechín, and Pampa de las Llamas-Moxeke All fall within what is called the Áspero tradition Other major Preceramic Pacific coast traditions are the Valdivia tradition (on the coast of contemporary Ecuador); the El Paraíso tradition (just south of the Áspero sites); and the Chinchoros tradition (centered at the Chinchoro complex near the contemporary Peru-Chile border) Archaeological excavations at these and other Preceramic coastal sites continue, as scholarly efforts to understand the civilizations that created them HIGHLANDS A related arena of debate among Andean archaeologists concerns the relationship between the Pacific coast settlements and the formation of complex societies in the highlands Most scholars agree that complex societies began to emerge in the Central and South-Central Highlands soon after the florescence of complex societies in the North Chico and other coastal valleys In the Central Highlands scholars have investigated what is called the Kotosh religious tradition at the Kotosh site Not unlike those in the North Chico, this site includes a series of raised mounds with platforms, sunken plazas, and an array of small buildings Sites exhibiting similar characteristics in the Central Highlands include Huaricoto, La Galgada, and Piruru In the South-Central Highlands the emergence of complex societies evidently began in the Lake Titicaca Basin around 1300 b.c.e Excavations at the site of Chiripa (in present-day Bolivia) have revealed that by this date there had emerged a nucleated settlement that included an array of small rooms, built of stone, with plastered floors and walls By 900 b.c.e the settlement of Chiripa included a ceremonial center surrounded by residential complexes Between 1000 and 500 b.c.e complex societies had emerged throughout much of the Lake Titicaca Basin To the north the Qaluyu culture reached florescence in the five centuries after 1000 b.c.e The Qaluyu type site, covering 17 acres, includes a large ceremonial mound, sunken plazas, and extensive residential complexes Other Qaluyu sites in the north Titicaca Basin include Pucará, Ayaviri, and Putina TITICACA BASIN The overall trajectory of this period was marked by the decline of North Coast polities and the rise of a