GED Science TestEarth and Space ScienceMedium
A geologist is examining rock layers in a mountainous region. They observe that older rock layers are found above younger rock layers, indicating that the rock sequence has been overturned. Which geological process is most likely responsible for this inversion?
- AFolding
- BDeposition
- CErosion
- DWeathering
Show answer & explanationAnswer & explanation
Correct answer: A. Folding
Intense compressional forces during mountain building can cause rock layers to fold so severely that they overturn, placing older layers on top of younger ones.
Why the other options are wrong
- B. Deposition adds new layers on top of older ones, maintaining the original sequence.
- C. Erosion removes material but does not invert the sequence of rock layers.
- D. Weathering breaks down rocks in place but does not change their stratigraphic order.
Folding (Geology)
The bending or curving of rock layers due to compressional forces within the Earth's crust, often resulting from tectonic plate collisions.
- Caused by compressional stress.
- Can form anticlines (arches) and synclines (troughs).
- Severe folding (recumbent folds) can overturn strata.
Memory trick: Rocks Bend and Break Under Pressure