Rivers are the great conveyor belts that carry sediment from mountains to the sea. In the Punjab — the Land of Five Rivers — a wholesale shift occurred in the past that re-routed sediment to different oceans. Rivers don't come much bigger than the Ganges and the Indus, both of which drain the mighty Himalaya. However, as Clift and Blusztajn show in this issue (page 1001), size does not mean permanence. Around five million years ago, the rivers of the Punjab evidently shifted from flowing into the Ganges system and the Bay of Bengal to flowing via the Indus system into the Arabian Sea. This major diversion of continental drainage has been deciphered from the isotopic signature of minerals collected from the Indus fan, a vast undersea cone of sediment stretching for more than 1,000 kilometres from the mouth of the Indus River.
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