Question

the third fossil is found in a rock layer near the bottom of the canyon (c).
what can a scientist infer about the relative ages of the fossils?
a. fossil a is younger than fossil c.
c. fossil c is younger than fossil a.
b. fossil b is younger than fossil a.
d. fossil c is younger than fossil b.

Explanation:

To determine the relative ages of fossils in rock layers, we use the principle of superposition: in undisturbed rock layers, the oldest layers are at the bottom, and younger layers are on top.

• For option A: Fossil A is in a layer (A) above fossil C's layer (C). So A's layer is younger, meaning Fossil A is younger than Fossil C. This is correct.
• For option B: Fossil B is in a layer (B) below Fossil A's layer (A). So B's layer is older, meaning Fossil B is older (not younger) than Fossil A.
• For option C: Fossil C is in a lower (older) layer than Fossil A, so Fossil C is older (not younger) than Fossil A.
• For option D: Fossil C is in a lower (older) layer than Fossil B, so Fossil C is older (not younger) than Fossil B.

Answer:

A. Fossil A is younger than fossil C.