CLIMATE, LANDSCAPE AND THE INDUS VALLEY CIVILIZATION IN SOUTH ASIA
Initial correlations between settlement geography and climatic signals were based upon deep testing and radiometric dating calibrated to soil formation chronologies, depositional histories of the Beas floodplains and terraces, and the cultural sequences of the Indus mounds. These integrated sequences are tied to a baseline climatic model that considered regional circulation systems and localized variability at gauging stations in the vicinity of the primary sites. These data underscored a trend to relatively stable and moister climates at the onset of settlement in the region, accelerations of channel migration and realignments of the Beas during the peak period of urbanization, and drastic realignments in precipitation and river discharge in the later stages of the civilization. Threshold transitions in the precipitation balance caused disruptions of the drainage net and hydrography that would have produced destabilization of landscapes tied to relocation of populations and abandonments of previously sustained settlements. In this study we consolidate the results of additional methodologies to test the settlement/environmental interpretations that were initially generated by first run field work, sequence chronologies, geomorphic analysis and climatic models. New data sets include higher resolution of relict channel configurations (observable in remote imagery and land use/soil maps), shifts in C4 to C3 stable isotope ratios attesting to transitions in vegetation covers and paleobotanical successions based on cropping patterns. Convergent global and local trends in the data sets bolster arguments for the impacts of climatic dynamics in the realignment of settlements in the Indus civilization during later stages of occupation.