Inferences from other bodies for the earth's composition and evolution

Abstract

Properties of the earth are considered in the light of the earth's presumed status as an end member of the class of predominantly silicate solar system bodies. Bulk composition data for the inner planets are presented and processes which may account for compositional variations are discussed. Problems posed by Viking findings on Mars and Pioneer findings on Venus are mentioned. Prominent evolutionary patterns of the inner planets are discussed, including the inverse correlation of lithospheric and crustal thickness with planetary size, and the thermotectonics of Venus, Mars, and earth are compared.