Question

the geologic cross sections show the locations of fossilized shells found at two sights about 2 miles from each other in the mountains of virginia. which of the following conclusions can made about the fossilized shells found at the two locations? the fossilized shells at q and z are most likely the same age. the fossilized shells at q formed before the fossils at m. the fossilized shells at m and q are most likely the same age. the fossilized shells at q formed before the fossils at z.

Explanation:

To determine the age relationship of fossils, we use the principle of correlation via a key bed (volcanic ash here). The volcanic ash layer is a time - marker. Fossils Z and Q are in rock layers that are correlated through this volcanic ash layer (they are at the same relative position with respect to the volcanic ash layer). So, the fossilized shells at Q and Z are most likely the same age.

• For the option "The fossilized shells at Q formed before the fossils at M": M is above the volcanic ash layer, and Q is below the volcanic ash layer (in its rock layer). So Q is older than M? No, wait, actually, the layer with M is above the volcanic ash, and Q's layer is below the volcanic ash (relative to the ash layer). Wait, no, looking at the cross - sections, the volcanic ash is a horizontal layer. The layer with Z is below the volcanic ash, and the layer with Q is also below the volcanic ash (in their respective cross - sections). Wait, no, in the left cross - section, from bottom to top: W (limestone - like), Z, volcanic ash, M. In the right cross - section: limestone, sandstone (with Q), volcanic ash, and the top layer. Wait, the volcanic ash is a key bed. So the layer containing Z and the layer containing Q are both below the volcanic ash layer. So they are of the same age (because the volcanic ash was deposited at the same time, so the layers below it in both locations were formed before the ash, and if the ash is a time - marker, then Z and Q's layers are contemporaneous).
• For "The fossilized shells at M and Q are most likely the same age": M is above the volcanic ash, Q is below, so they can't be the same age.
• For "The fossilized shells at Q formed before the fossils at Z": Since they are both below the volcanic ash (and the volcanic ash is a time - marker), they should be the same age, not Q before Z.

Answer:

The fossilized shells at Q and Z are most likely the same age.