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USGS CMG InfoBank: Radioactive Decay and Differentiation

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Comment: 12:05 - 12:52 (00:47)
Source: Annenberg/CPB Resources - Earth Revealed - 2. The Restless Planet
Keywords: "James Sadd", "radioactive decay", differentiation, "crustal formation"

Our transcription: The event which triggered the differentiation process was a dramatic heating of the Earth early in its history.
Several factors may have contributed to this heating, but the most important was the presence of radioactive elements in the rocks of primitive Earth.
As these elements decayed, their atoms emitted vast quantities of energy, which was rapidly converted into heat.
As the temperature of the Earth rose, rocks began to soften and partially melt.
While it's unlikely that the Earth became entirely molten, the heating and melting allowed the rocks to flow and change position or differentiate according to density.
The lightest material floated to the surface, forming a scum or crust on the Earth.
Denser rock and magma sank concentrating the heaviest material in the Earth's core.

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