The Thar Desert and its antiquity

For long, widely divergent views (based on isolated pieces of historical evidence or broad geological evolution of the subcontinent, notably the rise of the Himalayas in mid-late Miocene), had prevailed regarding origin and antiquity of the Thar Desert. Studies of the past few decades have since provided a wealth of new information on landform styles, evolutionary processes and palaeoclimate history with chronometric and isotopic constraints. Salt lakes, dunes and calcrete-bearing alluvial aggradations have been the focus of interest. This review synthesizes the multidisciplinary work to present the state of the Thar during the Quaternary period. Studies on salt lakes have provided high-resolution palaeoclimate records, but of the past ~ 15 ka BP only. Strong aeolian activity is a characteristic of the latest 200–300 ka period and is marked by several episodes of greater aridity, strong wind regime and sand dynamism followed by periods of stability implying climate amelioration and some pedogenesis. However, the preceding mid and early Quaternary periods are marked by alluvio-colluvial and sheetwash aggradations with pronounced, well-evolved calcretes therein. These findings strongly suggest that for much of the Quaternary period, the Thar region enjoyed a semiarid climate and the desertic conditions came to dominate much later.