image: The contact between a 3,250 million year old granite and 3,000 million year old sedimentary rocks, White Mfolozi Inlier, KwaZulu-Natal Province, South Africa. Chemical analyzes of such sediments shows that rocks similar in composition to the granites were the most abundant rocks in Earth's emerged lands since at least 3,500 million years ago. This material relates to a paper that appeared in the Sept. 22, 2017, issue of Science, published by AAAS. The paper, by N.D. Greber at University of Chicago in Chicago, Ill., and colleagues was titled, "Titanium isotopic evidence for felsic crust and plate tectonics 3.5 billion years ago." view more
Credit: © Axel Hofmann