News of the WeekGeophysics

Core Takes a Page From the Sea Floor

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Science  17 Nov 2000:
Vol. 290, Issue 5495, pp. 1274-1275
DOI: 10.1126/science.290.5495.1274b

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Summary

On page 1338, a group of geophysicists suggests that the mysterious boundary between Earth's molten iron core and its rocky mantle most resembles an inverted sea floor, with liquid-iron-laced sediments collecting on the roof of the core. They argue that a slow, inverted rain of precipitates rising to the core-mantle boundary and settling into a kilometers-thick layer might explain a variety of observations, from a subtle nodding of Earth's axis to seismic speed zones at the boundary. Their story will be difficult to verify, however, because painting a portrait of the core-mantle boundary depends on very indirect geophysical evidence.