Earth

Earth: Early continents were formed 500 million years ago than what was estimated

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Most of the Earth’s surface is surrounded by water. Only 30 per cent of it is land. The Origin of Continents is considered to be a critical stage in the history of the Earth. Life on Earth is also regarded as necessary in the development of life on Earth. In this sense also the coming into existence of continents is considered a significant link. It is unclear when the continents’ landmass first developed on Earth and under what tectonic processes they were formed. In the new study, researchers have found that the continents came into existence 500 million years earlier than previously expected.

Old rocks of these countries
In the study, published in the National Academy of Sciences, researchers studied the oldest continental fragments, called cratons, from older rocks from India, Australia and South Africa. The sand made from those rocks formed the world’s first beaches.

50 million years before the old estimate
According to previous research estimates, the researchers concluded that the first giant continents began to form around sea level about 3 billion years ago, compared to 2.5 billion years ago. When the continents began to emerge from the oceans, the wind and water began to break their rocks, which made sand, and through the rivers, they reached the beaches, which started the formation of beaches.

Signs of this are still present today
These processes can be seen on today’s beaches, but they have worked for billions of years. Geologists tried to know the history of continental formation by studying the records of signs of deposits of ancient sea coasts. In the eastern parts of the Indian subcontinent, a continental crust is made of old sand rocks in many places.

Zircon mineral particles
The crust consists of layers that were initially been deposits of sand on beaches, rivers and their mouths, which were later buried into rocks. The researchers tried to determine their age by studying the deposits of zircon mineral particles through microscopy studies. These minerals contain tiny amounts of uranium, which slowly turns into lead through radioactivity.

Estimating the age of the particles
Through this, the researchers got an opportunity to estimate the age of these zircon particles using the uranium-lead dating technique, which effectively determines the age of ancient rocks. These particles showed that the Singhbhum sandstone was deposited 3 billion years ago. This made them the oldest beach deposits in the world.

It also showed that the oceanic landmass that emerged in India was at least 3 billion years old. Interestingly, some sedimentary rocks from this period have been found in the Pilbara and Yilgarn Cratons of Australia and the Kapwal Craton in South Africa. This shows that many continental landmasses must have been formed during that period.

Researchers found that these continents were also very thick. Their protruding part was about 45 km wide, while their inner part used to be up to 40 km. Many parts were formed between 3.5 and 3 billion years ago and flourished a lot during this time. Their presence had a profound effect on the early Earth’s climate, atmosphere and oceans.