Divided simply by five
East Asia's mightiest rivers were once a single, even mightier torrent April 12th 2013 | CHENGDU | From your print release
The amazing First Bend
BY BUILDING atteinte in the Himalayas, Chinese technicians are tinkering with one of the planet's great units of watersheds. Five great streams—the Red River, the Yangzi, the Irrawaddy, the Salween and the Mekong—flow within just about one hundred and eighty kilometres (110 miles) of 1 another in the south-eastern edge of the Tibetan plateau, segregated by parallel mountain varies, before charging off to empty at some point in different seas. Yet study suggests that ahead of this plateau began to rise, 50m in years past, at least two of these streams, and possibly more, had been one. The evidence, gathered simply by Peter Clift of Louisiana State School and Zheng Hongbo of Nanjing Normal University, originates from examination of the Red River delta in the Gulf of Tonkin in Vietnam plus the middle reaches of the Yangzi. The notion the Red River delta was your mother estuary of East Asia was conceived about ten years ago by Marin Clark, after that at the Washington dc Institute of Technology, and Mr Clift believes that he offers confirmed it. By analysing data gathered by the olive oil industry, this individual has found the fact that volume of residue in the delta is much larger than it ought to be, given the Red River's relatively moderate size today. He has also shown, by studying isotopes of a material called neodymium, that much of this sediment, through the Himalayas, once came from a block of crust referred to as Yangzi craton, which underlies Yunnan and Sichuan. The ratio of two isotopes of neodymium differs among rocks from these two places. Between 45m and 23m years ago that shifted in one rich in Yangzi-craton rocks to 1 dominated by Himalayan rocks as now.
That shift, Mr Clift thinks, marks the steady separation with the Red and Yangzi rivers, and in particular the formation of a characteristic, famous in China, referred to as the Initially Bend of the Yangzi. This kind of bend, in...