Earth’s first emerged landmassDate: 13 November 2021 Tags: Geography & Environment
A new study has found out that Jharkhand’s Singhbhum region was the earliest continental landmass to emerge out of the sea.
Previous studies had indicated that continents rose from the oceans about 2.5 billion years ago. This has now been contested.
Geological signatures of ancient river channels, tidal plains and beaches were found in sandstones in Singhbum, aged over 3.2 billion years.
Researchers analyzed uranium and lead contents of tiny minerals present in the sandstones to find the age and the conditions for their formation.
The stones were found to have formed in river beds, shallow seas and beaches. These water bodies could exist only if continental land was formed.
This was the reason researchers inferred that Singhbum region existed above the ocean before 3.1 billion years.
This is not the only place which existed 3.1 billion years ago. Similar areas also exist in Australia and South Africa.
Granites forming the continental crust in Singhbum were analyzed. These granites were formed as a result of extensive volcanism that occurred 35-45 km deep inside the Earth.
This process took place about 3.5 to 3.1 billion years ago and continued for hundreds of millions of years until all the magma solidified to form continental crust.
The continental crust was less dense and thick, which allowed it to emerge above surrounding dense oceanic crust.
Researchers believe that the formation of land allowed proliferation of photosynthetic organisms.
These organisms increased oxygen levels in the atmosphere and helped in development of life in future.