Journal of Archaeological Science 36 (2009) 1006–1017 Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas Reconstructing landscape at Chavı´n de Hua´ntar, Peru´ : A GIS-based approach Daniel A. Contreras* Archaeology Center, Stanford University, P.O. Box 20446, Stanford, CA 94309, United States article info abstract Article history: The landscape around the prehistoric Peruvian ceremonial center of Chavı´n de Hua´ntar has undergone Received 1 October 2008 extensive geomorphic and anthropogenic change since the beginning of monumental construction at the Received in revised form site in approximately 1200 BCE. Archaeological and geomorphic stratigraphy from the site and its near 25 November 2008 periphery provide the data necessary to characterize these changes in detail. This paper reports on the Accepted 28 November 2008 use of GIS-based interpolation tools to approximate a complex prehistoric land surface using unevenly scattered point data. Such an interpolated surface serves as the basis for the reconstruction of the pre- Keywords: Chavı´n landscape and assessment of landscape change contemporary with the site. Peru GIS Ó 2008 Elsevier Ltd. All rights reserved. Chavı´n Interpolation Landscape 1. Introduction distributions of material culture rather than physical surfaces. This article emphasizes instead the interpretive utility of such a surface This paper presents an experiment in using GIS-based interpo- at Chavı´n de Hua´ntar, drawing on the combination of extant liter- lation tools to approximate a complex prehistoric land surface ature and the increased accessibility of software capable of carrying using unevenly scattered point data. Such a project is necessary to out computationally-intensive interpolations to consider what kind understand the archaeological landscape at Chavı´n de Hua´ntar due of a result may be produced, from what quantity and variety of data, to the extensive, complex, and multi-causal depositional history at and with what interpretive potential. As several studies have sug- the site, a first millennium BCE monumental center in the Peruvian gested (e.g. Forte, 2000; Katsianis, 2004; Stafford, 1995), under- Central Andes. The data are derived from a variety of sources, standing the paleolandscape can be critical to both qualitative and including primarily stratigraphic excavation and geomorphologic quantitative assessments of an archaeological site. Systematically survey. Incorporation of these varied data into a GIS has allowed collecting data about paleosurfaces is complicated, however, by the their synthesis into a single model, and ultimately the interpolation difficulty of identifying and accessing such surfaces as well as by of a topographically realistic pre-monument surface. That surface the need to systematically integrate data from diverse sources. In forms the basis for reconstructed landscape to which the modern the case of Chavı´n, where a dynamic geomorphic environment and and archaeological landscapes can be compared. prehistoric anthropogenic landscape modification have combined Interpolation of surfaces from discontinuous data has received to significantly alter that landscape, the task is worth addressing: increasing attention in archaeology in recent years (Conolly and interpolation is an important tool for understanding archaeologi- Lake, 2006; Hageman and Bennett, 2000; Lloyd and Atkinson, cally-relevant landscape change at the site. 2004; Robinson and Zubrow, 1999; Wheatley and Gillings, 2002), I describe the site and its setting and summarize the evidence though it was explored significantly earlier (Zubrow and Harbaugh, for landscape change there, before turning to the sources of data for 1978). Much of the focus has appropriately been methodological, this project, the means of integrating those sources, and the results stressing the advantages and limitations of various methods of of using an interpolated surface as the basis for a reconstructed interpolation as well as the theoretical underpinnings of those landscape. Such an approach has highlighted the linked inputs of methods, and much of the literature has concentrated on geomorphic and anthropogenic change and allowed the quantifi- cation of landscape change associated with the construction of the monumental center. The explicit description of a baseline against * Tel.: þ1 650 736 2852; fax: þ1 650 725 9247. which the archaeological and modern landscapes can be compared E-mail address: [email protected] is the fruit of an interpolated surface, while interpretation of the 0305-4403/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jas.2008.11.025 D.A. Contreras / Journal of Archaeological Science 36 (2009) 1006–1017 1007 processes creating the observed contrasts depends on the fleshing archaeological research in the Andes since Julio C. Tello’s 1919 visit, out of a reconstructed landscape on the skeleton of the interpolated and has been key to understandings of Peruvian culture history surface. (Burger, 1992; Conklin and Quilter, 2008; Kembel and Rick, 2004; Lumbreras, 1989; Tello, 1943, 1960). While there are some 2. Background disagreements about details of Chavı´n’s chronology and sociopo- litical mechanisms underlying its rise, there is broad archaeological Chavı´n de Hua´ntar, in a valley bottom at 3180 m on the eastern consensus that the site served as an important Andean ceremonial slope of Peru’s Cordillera Blanca, is a complex of stone-faced plat- center in the first millennium BCE. form mounds, terraces, and sunken plazas (Fig. 1) dating to roughly I here focus on the reconstruction of the landscape around 1200–500 BCE (all dates are given in calibrated radiocarbon years; Chavı´n before the beginnings of monumental construction, the chronology remains debated (Burger, 2008; Conklin, 2008; Rick currently dated to approximately 1200 BCE. This date is a conser- et al., 2008)). The site as visible today consists of two U-shaped vative choice; in spite of debates over Chavı´n’s chronology (see groups of structures, each opening to the east. Each group above), no suggestion of monumental architecture predating 1200 surrounds a sunken plaza (Fig. 2); the whole array is the product of BCE has been offered. many distinct construction phases spread over at least five hundred The site’s steep setting on the eastern flank of the Andes implies years (Kembel, 2008). One of only a handful of monumental high- a geomorphically active landscape (see Fig. 3), and a variety of land sites from this early period, the site has been a focus of pieces of evidence now suggest that the landscape associated with Fig. 1. Site map. Labels indicate features discussed in the text and site sectors. 1008 D.A. Contreras / Journal of Archaeological Science 36 (2009) 1006–1017 2007; Rick, 2005). Remnants of walls that canalized the Mosna River are still visible today, and Tello’s pre-aluvio´n photos show similar wall fragments lining the Wacheqsa River (Tello, 1960). It is also now apparent, from multiple excavations and investigations of natural exposures, that much of the near periphery of the monu- mental core, which does not today appear to be part of the built complex, in fact consists of series of terraces and platforms that have been obscured by colluvium. 3. Evidence of landscape change Chavı´n’s landscape between 2000 and 200 BCE was, recent work has made clear, significantly different than that visible today (Contreras, 2007; Rick, 2005; Turner et al., 1999). The changes of the last 3–4 millennia include both geomorphic and anthropogenic elements. 3.1. Geomorphic change Fig. 2. View of Chavı´n, looking west across the Mosna River at the site’s monumental Several generalized landscape processes can be distinguished as core. Note the Square Plaza (at left) and the Circular Plaza (above and to the right of the Square Plaza), each surrounded by platform mounds forming U-shaped arrays. active on a human timescale around Chavı´n. These include land- slide activity, colluvial deposition, flooding, landslide-driven river channel wander, and periodic debris flows. Evidence of such the monumental center was distinct from that now visible. Apart activity is spatially widespread and present across various land- from the substantial construction of the monumental complex scape phases. itself, the modern landscape is different in several particulars. Several significant geomorphic events heavily shaped the pre- Depositional events that have obscured the complex as well as its Chavı´n landscape. The notably flat expanse of valley floor on which setting include landslide and earth flow activity, including the modern town is situated is the result of a substantial (covering a historically documented major debris flow (known locally as an perhaps 70 hectares) paleolake, formed when the Mosna River was aluvio´n) in 1945 (Indacochea and Iberico, 1947). Moreover, move- dammed by a major rotational landslide on the east side of the ment of river channels as a result of landslide activity is a prom- valley (Contreras, 2007; Turner et al., 1999). inent feature of the local geomorphology; such channel The pre-monumental landscape was also significantly affected displacement not only constitutes a substantive landscape change by a substantial debris flow, the diamicton of which is visible in the but is also a major cause of erosion. cut on the south side of the Wacheqsa River. Also visible in the West In addition to these geomorphic changes, the landscape engi- Field