Question

in which situation is the principle of cross - cutting relationships useful in determining relative age?
a fault breaks through sedimentary layers.
fossils of two different species are found in different rock layers.
sedimentary layers form over millions of years in a lake bottom
lava flows form on top of one another from several eruptions over time.

Explanation:

The principle of cross - cutting relationships states that a geologic feature (such as a fault, intrusion) that cuts through another feature is younger than the feature it cuts. In the case of a fault breaking through sedimentary layers, we can use this principle. The sedimentary layers were formed first, and then the fault (which is a cross - cutting feature) broke through them.
For the option “Fossils of two different species are found in different rock layers”, we use the principle of fossil succession. For “Sedimentary layers form over millions of years in a lake bottom”, we use the principle of superposition (younger layers are on top of older layers). For “Lava flows form on top of one another from several eruptions over time”, we also use the principle of superposition.

Answer:

A. A fault breaks through sedimentary layers.