Perhaps the most impressive factors in D.L. Anderson's analysis of new physical models of the earth are contributions from the numerous disciplines of modern geophysics, including 3-dimensional seismological observations, high-pressure experiments, highly precise isotope analyses, and studies of other solar system bodies [Science, 223, pp. 347–355, 1984].
The results? In short, there are the “ins” and the “outs.” For example, the basalt-eclogite transition is back in fashion, whereas the notion of an olivine-rich deep mantle assemblage is no longer in fashion. This analogy is not to be construed as any return to old, preplate-tectonic concepts. Modern research, in the purest sense, is forcing “a reexamination of some long-held assumptions.”