Early Evolution of Continents

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Science  24 Jan 1997:
Vol. 275, Issue 5299, pp. 498-499
DOI: 10.1126/science.275.5299.498

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How did the continents form, and how long ago? These questions have been the subject of debate for 30 years. As Hofmann discusses in his Perspective, results reported by Sylvester et al. (p. 521) reveal that measurements of niobium and uranium isotopes indicate that ancient rocks from Western Australia are indistinguishable from modern mantle rock. This finding suggests that the mass and extent of continents today is comparable to that 2.7 billion years ago.