Land came up from within the sea, dramatically rising up from the water, changing the entire planet's geography, climate, and increasing chances of life in all its forms. Before this event, Earth was one massive ocean.
Before this rapid emergence of land, the planet's mantle was too soft to support mountain ranges and all the geographic features seen today, a new study has found, reports R&D. Researchers have found that shale sampled from various parts of the planet contains archived evidence of nearly unrecognisable traces of rainwater that led to the weathering of land from about 3.5 billion years ago.
Before this event, the Earth was nothing more than a large body of water, hot and inhospitable. As the mantle cooled down, land emerged from the sea and climate on Earth also became a lot more temperate and bearable. Also, as new land clashed with each other, mountains, valleys, and plateaus came to be.
In the Earth's timeline, about 2.7 billion years ago, the first supercontinent came to be. Called the Kenorland, researchers till now always thought that the continent formed over a period of between 1.1 and 3.5 billion years ago. This new study, however, suggests that this change happened rather quickly, reports Daily Mail. The study found that about two-thirds of all the landmass seen today emerged from the sea about 2.4 million years ago.
"The crust needs to be thick to stick out of the water," said Ilya Bindeman from the University of Oregon who led the study.
"When the Earth was hot and the mantle was soft, large, tall mountains could not be supported. Our data indicate that this changed exponentially 2.4 billion years ago. The cooler mantle was able to support large swaths of land above sea level," he explained.
It was also around this time that dramatic changes in climate triggered the blooming of life that was far more complex than life at sea, like plants, algae, and fungi. It was followed by a series of "glacial events", notes the report, between 2.4 and 2.2 billion years ago. "This bright surface afforded by the vast ice covering the poles started to radiate and reflect heat away from the planet. What we speculate is that once large continents emerged, light would be reflected back into space and initiate runaway glaciation," said Bindeman.
'Earth would have seen its first snowfall.'
This, in turn, led to the Great Oxygenation Event which happened about 2.1 billion years ago, where atmospheric oxygen spiked, which in turn increased the chances of life blooming.
The study was first published in the journal Nature.