MT ISSN 0327-5159 (impresa) / ISSN 1853-8126 (en línea) 169 ARTÍCULO Arqueología 25(1) enero-abril: 169-186 (2019) The use of air photointerpretation in archaeological landscape research: the case-study of a Colombian Andean plateau Lorena Rodríguez Gallo* Recibido: " 23 de febrero de 2018 Aceptado: 16 de agosto de 2018 Abstract The aim of this paper is to use historical aerial photographs for the reconstruction of Keywords archaeological areas nowadays disappeared due to urban growth; this is supported Aerial Archaeology by data from excavations and colonial documentation. In this case, we intend to Photointerpretation reconstruct and analyze the raised fields system built by the pre-Hispanic groups in Landscape Archaeology the Bogotá savanna, located in the Colombia Andean highlands. The results show that Bogotá savanna the hydraulic system significantly transformed the ecological environment: it controlled Pre-Columbian raised fields the mobility of rivers and seasonal floods, blocked water flows and flooded specific areas of the savanna. The objective of the pre-Hispanic groups was not to drain the savanna, but to manage the water to get the most out of it, coexisting with it. El uso de la fotointerpretación en la investigación de paisajes arqueológicos: el caso de estudio de una meseta andina colombiana Resumen El objetivo de este trabajo es mostrar el uso de la fotografía aérea para la reconstrucción Palabras clave de áreas arqueológicas hoy en día desaparecidas por el crecimiento urbano, apoyada Arqueología aérea por los datos provenientes de las excavaciones o de la documentación colonial. En Fotointerpretación este caso se pretende reconstruir y analizar el sistema hidráulico de campos elevados Arqueología del paisaje de cultivo construidos por los grupos prehispánicos de la Sabana de Bogotá en los Sabana de Bogotá Andes colombianos. Los resultados muestran que el sistema hidráulico transformó Campos elevados precolombinos significativamente el medio ecológico: controló la movilidad de los ríos y las inundaciones estacionales, bloqueó flujos de agua e inundó zonas específicas de la Sabana. El objetivo de los grupos prehispánicos no fue desecar la Sabana sino manejar el agua para sacar el máximo provecho, conviviendo con ella. * Coordinación de Investigaciones, Universidad Manuela Beltrán (UMB). Calle 36 Nro. 21-39 (CP 111311) Bogotá, Colombia. E-mail: [email protected] 170 ISSN 0327-5159 (impresa) / ISSN 1853-8126 (en línea) 171 Arqueología 25(1) enero-abril: 169-186 (2019) L. Rodríguez Gallo Introduction Throughout our time on the planet we have left traces of our actions, creating layers that overlap and form a palimpsest. This has been achieved through an intimate relationship between people and the environment whose synthesis is the landscape (Crumley, 1994). One of the tasks of archeology is to discover, understand and explain this particular interrelationship over time. Each human group, from hunter-gatherers to city dwellers, have lived in a specific ecological environment, transforming it for years or centuries according to their needs and the potential of nature, making it their home, their place of resource exploitation, the abode of their gods, in short, the space of creation and recreation of their social, political, economic, cultural and symbolic worlds (Balée, 2006; Crumley, 2007). However, today, when we look at the space that surrounds us, it is hard to imagine that it might reveal something of the life of human groups that lived there before us. In fact, most of the remains of this activity are currently found in the subsoil (with the exception of cases such as abandoned architectural structures or rock art found in rocks and caves). How can we reveal them when they are invisible to our eyes? In the main, archaeologists dig, searching for traces of human activity in the past. But, there are also other methodologies that allow us to “see” and study from the surface what is buried: aerial archeology is one of these (Parcak, 2009). The savanna is a lacustrine fluvial plain, difficult to drain, with a high number of seasonal and permanent water bodies. There, the pre-Hispanic groups built raised field systems, whose vestiges today have disappeared due to the urban growth of the country’s capital —Bogotá—over the last fifty years (Figure 1). However, we have an important collection of aerial photographs, taken in the decades from 1930 to 1960, where vestiges of the hydraulic system are still visible allowing us to reconstruct and analysis them. These remains, which represent the last phase of the pre-Hispanic period (Late Muisca: AD 1000 – 1550) were analyzed through aerial photography, with the support of data from excavations and colonial documentation, the aim being to understand how Muisca society transformed their ecological environment; how was their relationship with the water through the hydraulic system; how the process of human occupation took place and what was the spatial relationship between settlements and local croplands. Background: raised fields in the Bogotá savanna and its environment The Bogotá savanna is a plain of 1.413 km², located at 2600 m high in the eastern mountains of the Colombian Andean System (Figure 2). It was formed 25,000 years ago from the emptying of an ancient Pleistocene lake. The presence of multiple tributaries, whose only drainage valley was the Bogotá River, and its sandy-clay soil that was hard to drain, made of the savanna a floodplain with numerous marshes and lakes (Van der Hammen, 1995). The Bogotá River Basin crosses the plateau, cutting it in half in a northeast-southwest direction and running a length of 90 km (CAR, 2006), it constitutes the savanna’s main waterway. It is fed by several rivers such as the Frio, Chicú, Juan Amarillo, San Francisco, Fucha, Tunjuelito, and Balsillas. It also has wetlands such as La Conejera, Juan Amarillo, Jaboque, La Florida, El Guali, Cordoba and Tibanica, and Lake La Herrera (Figure 3). The plateau has a flat slope in the east-west, north-central and south-central directions. This makes the Funza-Bosa area the lowest and most prone to flooding of the plain, the altitude of which ranges from 2600 m at the foot of the eastern mountains to 2545 m on the floodplain of the Bogotá River (Boada, 2006, p. 26; Etayo, 2002, pp. 32-33). 170 ISSN 0327-5159 (impresa) / ISSN 1853-8126 (en línea) 171 The use of air photo interpretation in archaeological landscape research... Arqueología 25(1) enero-abril: 169-186 (2019) Figure 1. Aerial view of the Bogotá savanna plateau from east to west. In the central area it can be seen the Bogotá River limiting the expansion of Bogotá D.C. city. © L. Rodríguez Gallo Figure 2. Location of the study area. © L. Rodríguez Gallo It has an average annual temperature of 15ºC and is covered by forest vegetation (Van der Hammen, 1998). The varied geographical, morphological and ecological features of the savanna promoted the development of different types of human occupation, given that the presence of water was not a problem. The earliest human settlement in the region dates to 12400 years BC (Correal & Van der Hammen, 1977). The inhabitants were hunter-gatherers who settled in rock shelters and later on open-air settlements located in terraces or on the plain, away from the effect of floods. According to archaeological 172 ISSN 0327-5159 (impresa) / ISSN 1853-8126 (en línea) 173 Arqueología 25(1) enero-abril: 169-186 (2019) L. Rodríguez Gallo Figure 3. Study area. Bogotá savanna. © L. Rodríguez Gallo. Note: The rivers and wetlands as they looked in the 1950s; In green color: areas with remains of raised fields identified during the photointerpretation analysis. and bio-anthropological evidence, these same groups eventually shifted to horticulture and later agriculturalists organized into chiefdoms (Rodríguez Cuenca, 1999, 2011). Nevertheless, in order to successfully inhabit the floodplain, they had to transform its ecological structure by building raised fields. Throughout Latin America raised fields systems were constructed by pre-Hispanic societies. Both in the highlands and low tropical lands, from Mexico to Peru, these people transformed floodplains into productive agricultural systems (Delgado-Espinoza, 2002; Denevan, 1970; Erickson, 1988; Gassón, 1998; Hammond, 1984; Plazas et al., 1993; Valdez, 2006). The raised fields are earth structures with channels for drainage interspersed with elevated platforms for cultivation, built with the residual land of the channels. These channels distributed water in a controlled manner along the plain during winter. During summer, they could act as reservoirs, ensuring good harvests throughout the year. The raised fields system permitted not only the cultivation of flooded areas but also an increase in the productivity compared to traditional methods, since the organic matter accumulated in the channels during the floods was subsequently deposited on the platforms, enriching them with silt sediments. The raised fields system also helped to solve a problem that even today affects farmers in Andean regions: frost. During warmer months, from December to February and June to August, the temperature ranges from daytime maximums of 22 °C, to night temperatures of -5 °C. Consequently, the crops can get frost-damage. This hydraulic system neutralized this adverse effect, since the water channels were heated during the day, thereby keeping the earth warm at night, and thus preventing frost from damaging the plants. In the Bogotá savanna, the axis of the hydraulic