This paper presents a summary of work carried out by the author and his colleagues over the past 30 years. A register of sites with geoglyphs, together with their associated cultural and environmental contexts, constitutes the most complete database known for northern Chile, offering new possibilities for interpretation of the geoglyphs. The already classic bibliographic references of Alberto Plageman, summarised in his work 'Los Pintados de Chile' presented at the XIVth Congress of Americanists, and of Bollaert and O'Brien in the nineteenth century on the geoglyphs of the northern desert, were our precursors, and served as stimuli for other investigators in the second half of the twentieth century to follow in their footsteps--for example, Niemeyer, Nunez, Monstny, Bittmann; and, most recently, Clarkson, Briones, Chacama, Espinosa, Cerda and others.
The first systematic study of geoglyphs in Tarapaca was carried out by Lautaro Nunez (Nunez 1976), who presented an interpretation related to the traffic of caravans in the late period in the Chilean desert. Later, starting in 1978, and as a consequence of the deterioration of various sites around the Panamerican highway, a programme of appraisal and conservation was initiated in the valleys of Lluta, Azapa, Chiza, Tiliviche, Cerro Rosita, Cerro Unita and Cerros Pintados in the region of Tarapaca; and of Quillagua, Tranque Sloman and Chug-Chug in the region of Antofagasta. This process enabled us to discover new archaeological sites, carry out their exhaustive recording and documentation, and incorporate new background information on the geographical context and the landscape in which they occur. Together with previous observations (Boallaert 1860; Nunez 1976; Cerda et al. 1985; Mostny & Niemeyer 1983), this information has been gathered together to form a new comprehensive database. Based on this corpus, I offer a first analysis of regional groups and some preliminary interpretations (Figure 1).
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The term 'geoglyphs' was coined by Mostny & Niemeyer in 1983 to define the large figures laid out on the hillsides and pampas of the desert, distributed over an area extending from the lower course of the Lluta valley in the north, to the river Loa in the south. Geoglyphs occur in similar geographic locations in southern Peru where, in the desert strip next to the Pacific, there are spectacular examples, studied by Reiche (1980), Reinhard (1983), Clarkson (1992, 1998) and others. Taking both groups together, their distribution in the sub-area of the Western Valleys (southern Peru, northern Chile) covers an area of 1000km in length and 150km in width. The geoglyphs are found alone, or in groups of what we call 'panels', some of which may contain more than 50 figures.
The geoglyphs were made by taking full advantage of the geological and geographical characteristics of the desert. The majority were made by 'scraping' the oxidised layer of the surface, producing a light design that contrasts with the darker material all around. This is defined as an 'extractive' technique. We find examples of this technique in the groups at Cerros Pintados 1, Cerro Mono, Cerro Sombrero, Santa Rosita, in the gullies of Tarapaca, Altos Ariquilda, Mapocho and others, or on the pampas of Bajada Iquique, Cerro Unita, etc. The other technique, found less frequently, involves bringing together surface material (stones) like a mosaic, and is known as the 'additive' technique, in which the dark figures contrast with the lighter background of the desert floor. A third technique, which combines the two others, is known as the 'mixed' technique, and makes it possible to produce a harmonious contrast in the geoglyphs through both extraction and addition of material. The result is a figure of more complex design such as at Cerros Pintados, Altos de Tamentica, Guatacondo, Cerro Rosita and elsewhere. One example of an atypical or even unique technique is seen in the geoglyph of Alto Sur at the mouth of the Camarones gully: it is a 'sun' figure in a double 'mixed' technique--that is to say, it not only uses extraction and addition of surface material, but also red (liquid) paint. …