The Indian subcontinent was the scene of dramatic upheavals a few thousand years ago. The Northwest region entered an arid phase, and erosion coupled with tectonic events played havoc with river courses. One of them disappeared. Celebrated as -Sarasvati' in the Rig Veda and the Mahabharata, this river was rediscovered in the early nineteenth century through topographic explorations by British officials. Recently, geological and climatological studies have probed its evolution and disappear...