In an unconformity between two layers of rock, how is the lower layer usually described?

A. Much older than the lower layer.

B. Much younger than the lower layer.

C. The same age as the lower layer.

D. A little younger than the lower layer

A is the answer to the question

Lower layer is older than the upper layer

Explanation:

The unconformity is defined as the time of non-deposition. In simple words, it a contact surface between the older and younger sedimentary type of rocks, that results from the erosion particles over a specific period of time.

These sediments are deposited over one another over a due course of time, forming sedimentary rock sequences due to the compaction and lithification process. From the sequences it can be determined that the layers of rock that are at the bottom are considered to be the oldest layers, whereas the layers that are on the top are the younger layers. This is also known as the law of Superposition.

Hence, the lower layers are older than the upper layers.