Sedimentary layer A is found above sedimentary layer B, and the two are separated by a horizontal layer of ash, C. Therefore, the order from oldest to youngest is
A) B, C, A.
B) C, B, A.
C) A, C, B.
D) none of these.

Question

Quizplus · Accepted Answer

According to the principle of superposition in geology, in an undeformed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it. Therefore, if layer A is above layer B, and they are separated by a layer of ash, C, the order from oldest to youngest is B (oldest), then C, and A (youngest).

Sedimentary Layer a Is Found Above Sedimentary Layer B, and the Two