Reconstructing prehistoric environments in the Son and Belan valleys, north-central India: Retrospect and Prospect

Abstract

Pioneering archaeological surveys in the Son and Belan valleys of north–central India in the 1970s revealed that these valleys had been occupied at least intermittently during the Lower Palaeolithic, Middle Palaeolithic, Upper Palaeolithic and Neolithic. Later work in the early 1980s provided a reliable stratigraphic framework for the prehistoric sites and also resulted in the chance discovery of volcanic ash erupted from Toba volcano in Sumatra, Indonesia, 74,000 years ago. The discovery of the first Quaternary volcanic ash ever found in India prompted a search for the ash across the Indian sub–continent. By the early 1990s it was apparent that the entire sub–continent had been covered in a layer of ash 10–15 cm thick. Later work showed that some of this ash had been reworked by runoff and soil creep soon after deposition and accumulated in topographic depressions and valley bottoms where it remained in a relatively pure state. However, some of the ash has been reworked more than once since first deposited. Use of the ash as an isochronous marker depends upon establishing whether it is still in primary context and if not the degree to which it has been mixed with younger sediment. A key and as yet unresolved issue is whether or not the eruption had a major or minor regional and global environmental (including climatic) impact. High resolution records from speleothems, pollen spectra, varved lake deposits and ice cores will be needed to answer this question. The presence of similar stone artefact assemblages above and beneath the ash tells us nothing useful about the actual environmental impact of the eruption.