The Toba supervolcanic eruption: Tephra-fall deposits in India and paleoanthropological implications

Abstract

The 74,000 year-old supereruption of the Toba volcano, located in northern Sumatra, is recognized as one of Earth’s largest known eruptions and was certainly the largest of the Quaternary period (Smith and Bailey, 1968). It is hypothesized to have led to both global climatic deterioration (Rampino et al., 1988; Rampino and Self, 1992, 1993a) and the decimation of modern human populations (Rampino and Self, 1993b; Ambrose, 1998, 2003a, 2003b; Rampino and Ambrose, 2000). However, the severity of Toba’s impact on climate and hominins has been contested (Oppenheimer, 2002; GathorneHardy and Harcourt-Smith, 2003). Geological and archaeological evidence from the Indian subcontinent provides an excellent opportunity to address these issues. The scale of the Toba supereruption was so vast that it led to the deposition of a blanket of volcanic ash over India, Malaysia, the Indian Ocean, and the Arabian and South China Seas. Resulting terrestrial tephra deposits have been documented in a number of river valleys throughout India (Acharyya and Basu, 1993; Shane et al., 1995; Westgate et al., 1998). A handful of these localities preserve archaeological, paleontological and paleoenvironmental evidence which is in direct association with the tephra. This chapter is the first study to pull together this evidence, looking at the relationship between Toba ash and archaeology from sites across the Indian subcontinent. It is proposed here that the specific local impacts of the Toba eruption can be analyzed by applying a multidisciplinary approach to the archaeological and geological evidence from certain localities in the Indian subcontinent. This data can be combined with additional evidence from a wider context