Abstract The western edge of the Deccan Plateau (=Western Uplands) has been depicted in its evolutionary models to be a contiguous crustal block exposing structurally undisturbed subhorizontal stacks of Deccan Trap basalts. The geomorphological and morphometric characteristics of this terrain, Quaternary fluvial sediments capping the Deccan Traps in some river basins, compounded with deformation features in the basalts, and in the overlying sediments, are compiled here. They demonstrate that the Western Upland region of the Deccan Plateau may be constituted of no less than three blocks with differential Quaternary uplift histories, rather than the entire region experiencing a unified uplift.

Abstract The two Early Acheulian sites of Bori and Morgaon in the Deccan Volcanic Province in Upland Maharashtra, India bear some association with an acidic tephra deposit in a fluvial context. Acheulian artefacts in association with tephra were first reported in India from the Bori site and numerous efforts to date this tephra have since been undertaken. These efforts employed various dating methods and produced a total of 10 absolute dates ranging from the Early Pleistocene with a maximum age of 1.4 Ma to the Late Pleistocene with a minimum age of 23.4 ± 2.4 ka. However, field observations and a typo-technological analysis strongly suggests that these Early Acheulian artefacts occur in a semi-primary context, and thus contest the Late Pleistocene age of the tephra and redeposition of the artefacts as argued by some scholars. At Morgaon, the Acheulian artefacts have been recovered from basal fluvial sediments that contain clasts of laterite. These sediments are capped by two low-energy clay facies that are separated by high-energy gravel lenses. The tephra at Morgaon has been reported from the upper clay facies and has produced absolute dates ranging from the Matuyama period (>0.78 Ma) to the Late Pleistocene (41 ka). After more than two decades of investigation at these sites, the number of absolute dates procured through methods such as electron spin resonance (ESR), 39 Ar– 40 Ar, U–Th and palaeomagnetism, although encouraging, are inconclusive. This paper is therefore an attempt to gauge the nature of the palaeolandscapes that most probably existed during the Early Quaternary. This will be achieved by studying local geomorphological variability between the two sites, along with a preliminary analysis of lithic morphology.

Abstract Rivers and river-borne deposits have always been a major attraction for hominins as an important source of sustenance and settlements. Hence, fluvial deposits have long been an important source of evidence for early human occupation throughout the Old World. Apart from being an important palaeoclimatic marker, fluvial sequences have provided archaeologists with frameworks for correlation, along with Palaeolithic markers discovered within them. Moreover, given the influx of sediments eroded and deposited by Indian rivers, these could have acted as a centre of hominin activities. Palaeolithic research in India has been concentrated around some of its major river valleys, which have yielded a rich record of hominin occupation. So far, 305 Palaeolithic sites have been reported from a gravel context throughout the country, yielding Lower to Upper Palaeolithic, Mesolithic and Neolithic evidence. However, most of the derived evidence is secondary deposits and stands contested based on its contextuality. Nevertheless, its importance as a source of information about hominin activity cannot be underestimated. This review presents a provisional synthesis of all of the Indian Palaeolithic sites reported from gravel contexts, thereby presenting scope for future multidisciplinary research at these localities.

Abstract A discrete Toba Ash layer in the northeastern Arabian Sea was detected near the base of a 20.2 m long piston core (289KL) recovered from the oxygen minimum zone off the Indus delta. In addition to the Toba Ash, we discovered two highly disseminated, vitreous, rhyolitic ‘ash layers’ in two annually laminated box cores: a ‘Younger Ash’ (about AD 1885— 1900), and an ‘Older Ash’ (about AD 1815-1830). The glass shards were probably derived from eruptions of Indonesian volcanoes, although it was not possible to correlate these two ashes with well-known historical eruptions. We discuss source, transport and deposition of distal ash-fall layers in the Arabian Sea, which are derived from violent ultra-Plinian eruptions on the Indonesian volcanic archipelago, as well as their use for palaeoclimatic correlation. Core 289KL has a complete, high-resolution stratigraphic record of the past 75 ka with 21 interstadials (IS) or Dansgaard-Oeschger (D-O) cycles and equivalents of Heinrich events H1-H6. The high-frequency record of this core shows rapid climate oscillations with periods around 1.5 ka and can be tuned precisely to the 5 ,8 O record of a Bay of Bengal core and to the GISP-2 ice core from Greenland. The Toba event (70 ± 4 ka bp), which is well documented in the Arabian Sea and Bay of Bengal records at the end of IS-20, as well as in the Greenland ice, is an excellent stratigraphic marker horizon to validate this correlation. The apparent synchronous appearance of the various D-0 oscillations and Heinrich events, which has been documented for many northern hemisphere localities, can be explained only by fairly rapid atmospheric circulation changes. Changes in the intensity of the Indian summer monsoon are tightly coupled with suborbital climate oscillations in the northern hemisphere via atmospheric moisture and heat circulation.