Which is the largest delta in India

Where the largest river delta in the history of the earth was

The Ganges-Brahmaputra Delta in South Asia, currently the largest river delta in the world, covers around 110,000 square kilometers. And yet that is only a tenth of what the largest known delta in the history of the earth measured: it would have accommodated one percent of the total land mass today, reports a Norwegian research team in the journal "Geology".

The researchers found traces of this mega-delta in the Barents Sea, a marginal sea of ​​the Arctic Ocean between Norway and Russia. Its area of ​​1.4 million square kilometers should by and large coincide with the area of ​​the former delta, if the team from the University of Bergen has its way. This is supported by data obtained by means of reflection seismics, as well as rock samples taken from test drilling in search of oil deposits.

In the north of the world

Today's piece of seabed experienced its time as a river delta over 200 million years ago in the Triassic. At that time it was on the north coast of the supercontinent Pangea, into which all major land masses on earth had temporarily merged. According to the team around study author Tore Grane Klausen, it was probably several rivers that deposited the sediment layers typical of deltas. The material for this came from the interior of Pangea, the Urals and the Variscan Mountains, the last remains of which can be found today in Europe and the east of North America.

According to the researchers, the delta was likely to have existed for 237 to 227 million years ago - a long period that suggests that the (warm) climate and sea level were quite stable at the time. Fossils of ferns and gingko relatives suggest that the muddy plain of the "Snadd Delta" (named after a rock formation from which samples were taken) was overgrown and kept moist by monsoon rains.

Paradise with an inhospitable hinterland

Due to the lack of fossils, researchers can only speculate about the animal world of the Snadd Delta. Both the dinosaurs and the crocodiles only began to develop during this period. In their place, the humid fern forests between the arms of the river Labyrinthodontia were probably settled: relatives of amphibians that could reach the size of today's crocodiles. Ichthyosaurs are likely to have romped about in the water.

According to the researchers, the vast delta landscape may even have been an important biodiversity hotspot at the time. Because here there was an abundance of water and plants as the basis of a food chain. However, further south, in the arid interior of the supercontinent, it was much more inhospitable: perhaps similar to today's Central Asia, only - like almost everything in Pangea - one size larger. (jdo, April 6, 2019)