Question

assuming the rock layers in the diagram have not been disturbed, which of the three rock layers listed below is oldest?
toroweap formation
hermit shale
temple butte limestone

Explanation:

In undisturbed rock - layer sequences, the principle of superposition states that the lower the layer, the older it is. Without seeing the actual diagram, assuming a typical undisturbed sequence, the oldest layer is the one that was deposited first. Usually, the bottom - most layer among the given options is the oldest. Among the options, if we assume a normal depositional sequence, the Temple Butte Limestone is likely to be the oldest as it is likely to be the bottom - most layer in a typical undisturbed rock sequence compared to the others.

Answer:

Temple Butte Limestone