Question

the diagram above shows part of a geologic rock layer cross section. which of the following is correct about the diagram above? rock layer h is younger than igneous intrusion a, since a cuts across h. rock layers q and z were originally tilted, and later became flat. rock layer b is older than rock layer s rock layers q and z were originally flat, and later became tilted.

Explanation:

To solve this, we use the principle of original horizontality (sedimentary rocks are originally deposited flat) and cross - cutting relationships (a feature that cuts across another is younger).

• For the first option: If A cuts across H, then A is younger than H, so this is wrong.
• For the second option: Based on original horizontality, Q and Z (sedimentary - like) were originally flat and then tilted, so this is wrong.
• For the third option: In undisturbed layers, the lower layer is older. S is below B, so B is younger than S, this is wrong.
• For the fourth option: By the principle of original horizontality, sedimentary layers (Q and Z) are deposited flat and then tectonic forces tilted them. This matches the geological principles.

Answer:

Rock layers Q and Z were originally flat, and later became tilted.