Abstract The Quaternary sediments and landscapes of the plains of northwestern Haryana and the ancient settlement mounds distributed across them have great potential to reveal the history of the evolution and disappearance of palaeorivers and their relationship to the Indus Civilization and Early Historic periods in NW India. There are numerous palaeochannels in Haryana, and their distribution and burial in the subsurface creates difficulties for accessing the archives and proxies necessary for developing insight into the timing of river flow and shift, and its relationship to settled populations. This paper investigates the deep and shallow subsurface sedimentary lithology of an area around Sirsa that is close to the course of the modern Ghagghar River. The paper presents additional age constraints provided by dates from the site at Rakhigarhi and examines a sedimentary substrate of a new archaeological mound situated on a palaeochannel identified at a mound near Dhir village. New AMS radiocarbon dates of drifted charcoal from natural and cultural strata suggest human activity and/or natural burning in this region as early as 10 405–10 190 cal years BP (8455–8240 cal years BC). The substrate sediments recorded at the Dhir mound indicate flooding events after the urban phase of the Indus Civilization.

Abstract New geochronological and geochemical data from bedded porcellanitic tuffs present within two sedimentary basins at the eastern fringe of the Archaean Bastar Craton, eastern India (the Ampani and Khariar basins) are presented and compared with data available from tuffaceous beds present within adjoining basins. U–Th–total Pb electron probe microanalysis data of monazite grains from the Ampani tuff revealed several age data clusters: c. 2400, c. 2130, c. 1600, c. 1450 and c. 1000 Ma. An age of 1446±21 Ma is proposed as the depositional/crystallization age for the Ampani tuff, considering its maximum probability. Comparable ages for the tuffaceous units from the Khariar (1455±47 Ma) and Singhora ( c. 1500 Ma) basins allow us to infer a major felsic volcanic event during c. 1450 Ma at the eastern margin of the Indian Craton. Detailed geochemical data suggest rhyolite to andesite character for the siliceous tuff units from three geographically separated basins and point towards the presence of an active volcanic arc in a subduction-related setting in the region. The geochronological and geochemical data prompted us to search for other contemporaneous events in the Indian continent and beyond, that is, within its erstwhile neighbours in the Precambrian supercontinent ‘Columbia’.