Cultivated Wetlands and Emerging Complexity in South-Central Chile and Long Distance Effects of Climate Change
Dillehay, Tom D., Quivira, Mario Pino, Bonzani, Renee, Silva, Claudia, Wallner, Johannes, Le Quesne, Carlos, Antiquity
Archaeologists, geographers and historians have seen the grasslands and temperate forests of the southern cone of South America as backwater environments where only hunters and gatherers lived until AD 1550 to 1650 when the Spanish and other European cultures introduced new technologies. But new archaeological discoveries in the Amazon basin (Heckenberger et al. 2003) and mid-Atlantic region (Iriarte et al. 2004; Stahl 2004) have revealed unexpected cultural complexity in the form of monumental architecture, sedentary villages and social differentiation in cultural areas previously conceived as marginal. In this paper we focus on the region of Araucania, south-central Chile, where raised fields imply extensive artificial agricultural systems, associated with ceremonial mounds, in the cool, temperate rainforests between AD 1000 and 1500. From these landscape features we infer intense crop production in wetlands and correspondingly new principles of order and organisation and social differentiation.
Although mounds in the study area have been investigated previously (Latcham 1928; Dillehay 1985; 1990a; 2007), raised and canalised fields and their association with mound complexes have only recently been identified and studied. Cultivated fields in the region reported here are located in the coastal drainage of Lake Budi, in the delta of the nearby Imperial River and in the floodplain of the Puren and Lumaco Valley (Figure 1). We go on to explore the possibility that the technology of these fields might have been introduced by central Andean or Amazonian populations moving into more humid southern environments in response to prolonged aridity between AD 1000 and 1300 in their homelands.
Mound complexes in Araucania
Archaeological mound complexes in the floodplains and riverine estuaries of south-central Chile are large and numerous, date prior to AD 1000, and have their origins in local traditions and probably in central Chile (Dillehay 1985; 1990a & b; 2007). In the Puren and Lumaco Valley, more than 350 ceremonial and burial mounds, or kuel, are built on artificial platforms that are associated with public plazas (Figure 2). Some Puren/Lumaco complexes comprise up to 40 mounds, but most are small sites consisting of five structures or fewer and usually associated with nearby agricultural settlements, later defensive sites and the agricultural features discussed below. Diagnostic ceramics recovered from the fields and from nearby mounds and habitation sites are of the late Pitren and polychrome El Vergel traditions which are radiocarbon dated between c. AD 1000 to 1500 (Menghin 1962; Dillehay 1990a; 2007; Adan & Mera 1997; Quiroz & Sanchez 1997). Kuel are also found in other valleys in the Araucanian region, including the Budi and Imperial areas, but are less numerous and appear to date after AD 1100. Although the period of concern here is between AD 1000 and 1300, these complexes range between 2 and 10ha in size and date from c. AD 900 to the present-day. Some complexes are still in ceremonial use today by a few Mapuche communities in the Puren and Lumaco Valley (Dillehay 1985; 2007).
Raised and canalised fields
Raised fields are platforms where the topsoil has been elevated to protect it from excessive water and they provide a highly productive and important economic base for several Old World and New World civilisations (Denevan 1970; 2001). The most extensive raised fields in the New World are located in the tropical lowlands of Latin America (Turner & Brush 1987; Denevan 2001; Balee & Erickson 2006). Canalised fields are sinuous ridges that follow the natural contours of levees in the floodplain wetlands. Channels are often cut artificially between levees to facilitate and manage the flow of water for cultivation of the flat surfaces. Raised and canalised fields have been documented in several areas of the northern and central Andes, but never before in the southern cone and Araucanian region of South America. …