How Bangladesh was formed and why the Himalayas are still growing taller

Present-day Bangladesh was created in 1971 after India defeated Pakistan in 1971 and the erstwhile East Pakistan won its freedom struggle. But, the real geographical mass that constitutes the small, but thickly populated, eastern neighbour of India was formed in a unique geological process says a consortia of Indian & US earth scientists.

Over millions of years, soil erosion with massive volumes of sediment brought in by the rivers Ganges and Brahmaputra from the Himalayas buried the primitive oceanic rocks of the Bay of Bengal.

Consequently, the steady filling up of the proto Bay of Bengal region led to the formation of a new landmass, which constitutes most part of the Bangladesh territory, says KS Krishna, Head, Centre for Earth, Ocean and Atmospheric Science (CEOAS), at the University of Hyderabad (UoH)

He, along with other members of the research consortia— Mohammed Ismaiel, DST-INSPIRE faculty and the National Institute of Oceanography (NIO) have revealed an ancient ocean floor hidden under Bangladesh. These findings have been published in the latest issue of Current .

The Oil and Natural Gas Corporation (ONGC) and Rice University, Houston, have also been part of the Consortia that have been carrying out painstaking research on understanding the tectonic evolution of the Bay of Bengal and Bangladesh.

Researchers probed into the the scenarios of the great geological breakup of continents and the drifting of landmasses from the ancient Gondwanaland millions of years ago to form many of the present day known continents and mountains, including the Himalayas.

Their focus was on the proto Bay of Bengal region and the gradual formation of most of the Bangladesh territory over the ancient ocean floor.

Explains KS Krishna: “Our work unveiled that oceanic rocks were accredited by the seafloor spreading up to Kolkata and towards the north up to the Rajmahal–Sylhet line, close to the Shillong Plateau.”

The presence of continental slivers in global oceans either completely buried under the sediment or surviving as islands were identified earlier, but the existence of oceanic rocks beneath the landmass is identified for the first time, which may be a unique case on the planet Earth, he claimed.

Interestingly, geological theories have shown how the great Himalayas have been formed as a result of the collision between the Indian Plate and the Eurasian Plate, which began more than 50 million years ago. They still continue, though very slowly, hence the Himalayas still keep growing tall.

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