The ocean covers more than 70 pct of the airfoil of Earth today , but over 3 billion years ago the intact planet may have been covered in water .
To investigate what our planet was like billions of class ago , a team of researchers turned to collateral method acting of analytic thinking at a geological site in the Australian Outback known as Panorama in the Pilbara Craton . Today , the region is 100 kilometer ( 62 miles ) inland , but 3.2 billion years ago , it was deep underwater . In fact , there were also once ancient hydrothermal vent there where brine bubbled up through the sea floor .
" There are no samples of really ancient ocean urine lie down around , but we do have rock that interact with that seawater and remembered that fundamental interaction , " lead source Benjamin Johnson , an assistantprofessor at Iowa State University , suppose in astatement .
The researchers collected over 100 of theserocksamples and rule something peculiar in them : a somewhat higher amountof a particular isotope of atomic number 8 . An isotope is a interpretation of an constituent that has a different issue of neutrons in its nucleus . The Brobdingnagian majority of O on Earth is Oxygen-16 and contains eight proton and eight neutron . However , about0.20percent of the satellite ’s atomic number 8 consists of 10neutrons and is known as Oxygen-18 .
sample distribution from Australia show that the part ’s ancientwater contained more Oxygen-18 than present time . Since continents are shroud in clay - robust soil that is effective at ensnare Oxygen-18 , the team advise that without Continent covered in soil , more Oxygen-18 would have been present in the sea . Their discovery indeed propose there wasn’tmuch teetotal land uncommitted 3.24 billion years ago .
" There ’s nothing in what we ’ve done that enjoin you ca n’t have teeny , micro - continents sticking out of the ocean , " added co - author Boswell Wing , an associate professor in the Department of Geological Sciences at the University of Colorado Boulder . " We just do n’t think that there were global - scale formation of continental soils like we have today . “The researchers do n’t know when and how continents get down to emergeout of the sea butthey contrive to investigate “ youthful ” rock formation to piece together a more accurate timeline . The finding are reported inNature Geoscience .
