River response to Quaternary climatic fluctuations: evidence from the Son and Belan valleys, north-central India

Two older phases of prolonged aggradation followed by vertical incision are evident in the Son and Belan valleys before ∼39 ka. One of these phases is centred towards 73±4 ka when ash from the Toba mega-eruption in Sumatra was deposited across peninsular India. The following phase of aggradation has yielded infrared stimulated luminescence ages of 58±6 and 45±12 ka. The youngest phase of aggradation began towards ∼5.5 ka and seems to mark a return to a weaker summer monsoon regime.