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The earth as a planet - Paradigms and paradoxesThe independent growth of the various branches of the earth sciences in the past two decades has led to a divergence of geophysical, geochemical, geological, and planetological models for the composition and evolution of a terrestrial planet. Evidence for differentiation and volcanism on small planets and a magma ocean on the moon contrasts with hypotheses for a mostly primitive, still undifferentiated, and homogeneous terrestrial mantle. In comparison with the moon, the earth has an extraordinarily thin crust. The geoid, which should reflect convection in the mantle, is apparently unrelated to the current distribution of continents and oceanic ridges. If the earth is deformable, the whole mantle should wander relative to the axis of rotation, but the implications of this are seldom discussed. The proposal of a mantle rich in olivine violates expectations based on evidence from extraterrestrial sources. These and other paradoxes force a reexamination of some long-held assumptions.
Document ID
19840037635
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Anderson, D. L.
(California Institute of Technology Pasadena, CA, United States)
Date Acquired
August 12, 2013
Publication Date
January 27, 1984
Publication Information
Publication: Science
Volume: 223
ISSN: 0036-8075
Subject Category
Lunar And Planetary Exploration
Accession Number
84A20422
Funding Number(s)
CONTRACT_GRANT: NSF EAR-81-15236
CONTRACT_GRANT: NSG-7610
Distribution Limits
Public
Copyright
Other

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