The other day I was talking to a geologist friend of mine who told me about a pebble she found that held a clue to the amount of carbon dioxide in Earth's atmosphere 3.2 billion years ago.The walnut-sized pebble, she explained, was found in a slender core sample drilled from a gold mine in South Africa its timeworn surface long ago weathered to a rind by running water. My geologist friend discovered that the pebble's crusty skin is made of quartz (like white beach sand) and iron-rich carbonate minerals.The iron-rich carbonate is the clue. Carbonate contains a lot of carbon.
De skal dypere ned i urtiden. Forskerne Victor A. Melezhik og Aivo Lepland skal bore seg inn i 2,5 til 2 milliarder år gamle bergarter i Russland. De jakter på samspillet i de geologiske prosessene som skapte den "moderne Jorden".