Following this introduction, chapter 2 provides an overview of theoretical approaches to exchange and to raw material procurement areas from anthropological studies worldwide. Chapter 3 shifts the focus to the Andes with a review of the existing research that informs this investigation. In chapter 3 a discussion of economy, exchange, and long-distance interaction in the region is presented, as well as a summary of the evidence of Chivay obsidian consumption through time. Chapter 4 is a geographically oriented chapter with a discussion of the region in terms of climate, economy, geology, obsidian deposits, and finally the original chemical sourcing work that accompanied this research project. Chapter 5 describes the methods used in this dissertation with a focus on the novel methods employed by this project. Chapter 6 presents the results and analysis of a 33 km2 archaeological surface survey in six blocks throughout the Upper Colca study area. Chapter 7 describes the results of the testing program that included eight 1x1m test units, five of which are analyzed in detail here. Finally, chapter 8 is the summary of significant findings from this research and chapter 8 strives to reconcile the results of this research with the theoretical objects of the study.
While a major methodological goal of this project was to exploit new technologies for spatial data and the organization of information, the presentation in this Ph.D. dissertation is largely confined by the traditional format of the library monograph. Large segments of data from this project are available online at
http://www.MapAspects.org/colca/
where additional maps, photos of features and artifacts, and searchable GIS datasets are available permanently. Links to online materials are provided, as well, in the Appendices at the end of this document.
Throughout this dissertation chronology will be discussed in calibrated years Before the Common Era (BCE). Where possible, 14C dates will be completely reported using the form that follows. The actual radiocarbon years before present will be presented with a lowercase "bp", the laboratory identification will follow, and then the range of 2? (95.4%) calibrated Before Common Era dates are shown as reported by OxCal v3.9 (Ramsey 1995;Ramsey 2003) using data presented in Stuiver, et al. (1998). Calibrated Before Common Era dates are shown with the uppercase letters "BCE".
Most spatial data from the Andes is in coordinate systems referenced to the Provisional South American Datum of 1956 (La Canoa) based on the International 1924 ellipsoid. In order to be compatible with topographic data, imagery, and the datum native to the GPS system the coordinates have all been converted to the modern WGS1984 datum using the ArcGIS three parameter transformation function "1208: PSAD_1956_To_WGS_1984_8". The 1991 three parameter transformation to WGS1984 for metric UTM data for Peru is as follows ?X = -279 m ± 6 m, ?Y = +175 m ± 8 m, ?Z = -379 m ± 12 m, and was based on 6 collocated points (Mugnier 2006).
A GIS database of chemically-sourced obsidian samples has been compiled from the central and south-central Andes based almost entirely on published materials. In the text that follows travel times are been reported between the source and the consumption locale as calculated using Tobler's (1993) Hiking Function. This function models travel velocity as a function of slope.
Walking velocity (km/hr) = 6 exp (-3.5 * abs (S + 0.05))
Where S = slope in degrees (?Z/?X)
Figure 1-2. Tobler's (1993) Hiking Function models foot travel velocity as a function of slope.
Tobler's function follows Imhof (1950) in deriving travel speeds of 5 km/hr on flat terrain and an optimum travel speed of just over 6 km/hr on a -3.5° downslope. Further elaboration of this hiking speed function, such as on or off path travel and llama caravan versus hiking speed was not attempted as there are too many unknowns to reliably model such differences. While the absolute travel velocity may be unreliable, the relative speeds for comparing one consumption site to the next are informative and correctly factor in the effects of travel over steep terrain versus travel across the gentle slopes of the altiplano. The function has been used elsewhere in archaeological contexts (Gorenflo and Gale 1990;Jennings and Craig 2001; href="/biblio/ref_4270">Kantner 1996;Van Leusen 2002).
Topographic data used in this project derive from GPS and from Digital Elevation Models (DEM) generated from two space-borne remote sensing platforms. Three dimensional GPS data was gathered throughout the project using Trimble GPS units and post-processed using the Arequipa IGS base station. Local topographic relief was acquired from the ASTERDEM dataset (30m), and regional scale topographic data was acquired from the SRTM (90m) dataset. As will be described in more detail in Chapter 5, ASTER imagery and DEM data proved to be extremely useful in designing and executing this work in the mountainous terrain of the Chivay source area.
Quickbird satellite imagery for portions of the study region were made available in 2006 as a part of GoogleEarth v4. These data are distributed by DigitalGlobe and they are 2.4m per pixel multi-spectral imagery pan-sharpened with 0.68m per pixel panchromatic imagery for natural color imagery, and GoogleEarth topographic relief is blended into the imagery from the SRTM 90m layer.
Linear units used in this project are exclusively metric. A tape measure was extended to exactly 1m in landscape photographs to provide scale. Despite the tape not being legible, the total length of the exposed tape is always 1m unless otherwise noted. In some instances the tape is not perpendicular to the photographer position, a situation that could lead to foreshortening and in such cases the 1m scale would become invalid. Laboratory photos were taken on a matte grey background with a 1cm grid in the background. Additional notes regarding the methodology are provided in Chapter 5.