What does the law of superposition state?

What does the law of superposition state?

• A. Fossils are identical across layers.
• B. Deeper layers are younger than shallower layers.
• C. Underground layers closer to the surface were deposited more recently.
• D. The age of a rock is determined by its color.

Answer: (C)

In an undisturbed sequence of sedimentary rocks, the oldest material settles at the bottom and newer layers are deposited on top. As you move upward, the rocks become progressively younger because each new layer is laid down after the ones beneath it. So, layers closer to the surface were deposited more recently. This principle lets geologists establish relative ages of rocks and fossils within a sequence, provided the stack hasn’t been broken up by folding, faulting, or intrusion. Color isn’t a reliable indicator of age, and fossils don’t have to be identical across layers.

In an undisturbed sequence of sedimentary rocks, the oldest material settles at the bottom and newer layers are deposited on top. As you move upward, the rocks become progressively younger because each new layer is laid down after the ones beneath it. So, layers closer to the surface were deposited more recently. This principle lets geologists establish relative ages of rocks and fossils within a sequence, provided the stack hasn’t been broken up by folding, faulting, or intrusion. Color isn’t a reliable indicator of age, and fossils don’t have to be identical across layers.