Science. 1984 Jan 27;223(4634):347-55. doi: 10.1126/science.223.4634.347.
The 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.
在过去的二十年中，地球科学的各个分支的独立发展导致了地球物理、地球化学、地质学和行星学模型在地球组成和演化方面的分歧。小天体的分化和火山活动以及月球上的岩浆海洋与主要由原始、未分化和均匀的地幔组成的假说形成了鲜明对比。与月球相比，地球的地壳薄得惊人。大地水准面本应反映地幔中的对流，但它显然与当前大陆和大洋脊的分布无关。如果地球是可变形的，整个地幔相对于旋转轴应该会漂移，但这种情况很少被讨论。地幔富含橄榄石的提议违反了基于外星来源证据的预期。这些和其他悖论迫使人们重新审视一些长期以来的假设。
