What does the law of superposition state about the relative age of deeper rock layers?

• A. Younger than layers above
• B. Older than layers above
• C. Contains more advanced species
• D. Depth cannot indicate age

Answer: (B)

The law of superposition says that in a stack of sedimentary rock laid down in sequence without disturbance, the oldest material is at the bottom and each higher layer is younger. So deeper rock layers are older than the layers above them. This principle lets us compare relative ages even without exact dates. If the sequence has been tilted, folded, faulted, or intruded by magma, the straightforward order can be disrupted, but in an undisturbed stack, depth directly indicates that the bottom layers are oldest.