Ancient Agriculture on Lava Flows: Using LiDAR and Soil Science to Reassess Pre-Hispanic Farming on Malpaís Landforms in West Mexico

Abstract. The Mexican Central Highlands have been a major cluster for human settlement since pre-Hispanic times and its soils provide much of the food for modern Mexico. Rainfed cultivation yielded and still yields most of the agricultural products. However, pre-Hispanic rainfed cultivation has been less documented than other practices. Moreover, textual and ethnographic records, mostly postdating the deep modifications made by the Spanish conquerors, have long been prevalent in studies on pre-Hispanic farming and have tended to bias our conception of the latter. Archaeology provides new key information but struggles to address rainfed techniques, which leave few remains behind in some landscapes. To that regard, spatial approaches considering geoecological parameters are helpful. Furthermore, remote sensing techniques and airborne laser scanning (LiDAR), above all, offer increasing potential for feature detection and provides new ways to address fossilized landscapes at both archaeological and environmental levels. This paper offers new insights on pre-Hispanic rainfed cultivation through an interdisciplinary approach. It focuses on archaeological settlements on malpaís landforms (young and rugged lava flows) in the Malpaís de Zacapu, in western Mexico. There, a method combining fieldwork and remote sensing in archaeology and soil science was developed to reassess pre-Hispanic farming. After presenting the method and this study's main results, I discuss the latter in light of examples of ethnohistorical and ethnographical uses of malpaís landforms. They suggest that widespread conceptions about agricultural soils of the Mexican Central Highlands held by external observers differ from Indigenous and local farmers' notions, which seem partly inherited from pre-Hispanic times.