TeXes Science Practice Test

What characteristic defines foliated metamorphic rocks?

1. They have a granular texture.

2. They have minerals arranged in parallel layers.

3. They are formed under high pressure and high temperature.

4. They contain no distinct layers.

The correct answer is: They have minerals arranged in parallel layers.

The defining characteristic of foliated metamorphic rocks is that their minerals are arranged in parallel layers. This layered structure occurs due to the high pressures and temperatures that these rocks experience during their formation, which causes the minerals to realign and orient themselves in a planar fashion. This foliation gives these rocks their distinct appearance and makes them different from other types of metamorphic rocks that do not show this layer formation. While high pressure and temperature contribute to the formation of foliated rocks, the presence of parallel mineral layers is the primary defining feature. The other choices do not accurately describe foliated metamorphic rocks; for instance, a granular texture would refer more to non-foliated rocks, which lack this distinct layering, and a description indicating no distinct layers would directly contradict the very definition of foliated rocks.