Question

which statement explains one reason why unconformities occur?
o rocks along a fault break and move.
o igneous rock forms at earths surface.
o no sediment is deposited over a long time.
o igneous rock forms between sedimentary layers.

Explanation:

• Analyze each option:
• Option 1: Rocks along a fault breaking and moving relates to faulting, not directly to unconformities (unconformities involve gaps in the rock record due to erosion or non - deposition).
• Option 2: Igneous rock forming at Earth's surface (extrusive igneous rock formation) does not explain unconformities. Unconformities are about the lack of sediment deposition or erosion between rock layers.
• Option 3: Unconformities represent gaps in the geological record. If no sediment is deposited over a long time, there will be a gap between the older and younger rock layers, which is an unconformity.
• Option 4: Igneous rock forming between sedimentary layers is an intrusion, which is a different geological process and does not cause unconformities.

Answer:

C. No sediment is deposited over a long time.