ASVAB (Armed Services Vocational Aptitude Battery)General Science (GS)Medium
A geologist is studying rock formations and observes distinct layers with fossils of marine organisms. Which type of rock is she most likely examining?
- AVolcanic rock
- BMetamorphic rock
- CIgneous rock
- DSedimentary rock
Show answer & explanationAnswer & explanation
Correct answer: D. Sedimentary rock
Sedimentary rocks are formed from the accumulation and compaction of sediments, often in layers, and are the only type of rock that commonly contains fossils due to their formation process from organic remains.
Why the other options are wrong
- A. Volcanic rock is a type of igneous rock and does not typically contain fossils.
- B. Metamorphic rocks are formed from existing rocks altered by heat and pressure, usually destroying any original fossils.
- C. Igneous rocks form from cooled magma/lava and typically do not contain fossils.
Sedimentary Rock
Rocks formed from the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation.
- Often characterized by layers (strata).
- The only rock type that commonly contains fossils.
- Formed through processes like weathering, erosion, deposition, compaction, and cementation.
Memory trick: Igneous is fiery, Sedimentary is layered, Metamorphic is changed.