The oldest rocks on earth?
These are the oldest known rocks: http://www.msnbc.msn.com/id/26890176/ The oldest rocks which shown evidence of past life (that i am aware of) are the akilia sediments (3,850 million years old), these do not contain any fossils, but as photosynthetic organisms ‘fix’ a higher proportion of carbon 12 then carbon 13 through photosynthesis, the ratio of these isotopes within the rocks can be measured and compared. The oldest fossils date back around 3,465 millions years, the evidence is patchy, these consist largely of stromatolites, structures formed by sediments being cemented together by microorganisms.
