Smivs writes "The BBC reports that Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada. Writing in Science journal, a team reports finding that a sample of Nuvvuagittuq greenstone is 250 million years older than any rocks known. It may even hold evidence of activity by ancient life forms. If so, it would be the earliest evidence of life on Earth — but co-author Don Francis cautioned that this had not been established. 'The rocks contain a very special chemical signature — one that can only be found in rocks which are very, very old,' he said."