Contents

17 September 1976
Vol 193, Issue 4258

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El Misti, a young (Pleistocene) stratovolcano in southern Peru. The volcano is composed of andesites bearing a 300-million-year strontium isotopic age imprint inherited from ancient sub-Andean lithosphere. See page 1086. [C. Brooks et al., Carnegie Institution of Washington, Washington, D.C.]