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Difficulty: EasyEarth's History and Paleontology

According to the Law of Superposition, in an undisturbed sequence of sedimentary rock layers, where is the oldest layer of rock located?

  1. A
    At the very top of the sequence
  2. At the very bottom of the sequenceAnswer
  3. C
    Within any igneous rock cutting across the strata
  4. D
    Evenly distributed throughout the middle strata

Answer

At the very bottom of the sequence
The Law of Superposition is a fundamental principle of relative dating which states that in an undisturbed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it. Consequently, the oldest layer is always situated at the very bottom.

Step-by-Step Solution

1
Identify the geological principle referenced in the question
The Law of Superposition applies to undisturbed horizontal layers of sedimentary rock.
Understanding the rule governing relative age determination in stratigraphy is the first step.
2
Apply the rule of deposition to determine relative age based on depth
Since new sediments accumulate on top of pre-existing sediments, the deepest layer was deposited first and is the oldest.
Gravity causes successive sediments to settle on top of older foundations.

Key Concept

Law of Superposition in Relative Dating
Estimated Time:40s
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Topics

Earth's History and Paleontology

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