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USGS CMG InfoBank: Relative Age Sequence

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Comment: 10:39 - 11:23 (00:44)
Source: Annenberg/CPB Resources - Earth Revealed - 10. Geologic Time
Keywords: "Principle of Original Horizontality", "Principle of Superposition", "Principle of Cross-cutting Relationships", unconformity, "James Hutton"

Our transcription: According to the "Principle or Original Horizontality", beds of sediment form as horizontal layers as the sediment settles under the force of gravity.
The "Principle of Superposition" maintains that the oldest layers of undeformed sedimentary strata are on the bottom and the youngest on top.
Finally, the "Principle of Cross-Cutting Relationships" states that a rock is younger than any rocks it cuts across, as in the case of veins of igneous rock cutting across strata or unconformities, such as Hutton studied.

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Page Last Modified: Thu Oct 31 04:26:11 PDT 2013  (chd)