AFOQT Practice Test

What is the primary cause of changes in metamorphic rocks?

1. The flow of water

2. Heat, pressure, and chemical reactions

3. Cycling of weather patterns

4. Evaporation and condensation

The correct answer is: Heat, pressure, and chemical reactions

The primary cause of changes in metamorphic rocks is heat, pressure, and chemical reactions. Metamorphic rocks form when existing rocks—igneous, sedimentary, or other metamorphic rocks—undergo a transformation due to significant increases in temperature and pressure typically associated with deep burial or tectonic processes. Heat can cause minerals within the rocks to recrystallize, leading to changes in their physical properties and appearance. Additionally, the application of pressure can result in the alignment of minerals along specific planes, creating a foliation effect within the rock. Chemical reactions often occur in conjunction with these processes, especially in the presence of mineral-rich fluids that can facilitate the exchange of ions, promoting the growth of new minerals that are stable under the new temperature and pressure conditions. This comprehensive interaction of heat, pressure, and increased chemical activity is what ultimately leads to the formation of distinct metamorphic rocks, differentiating them from their parent rock types. The other provided options do not appropriately capture the primary mechanisms involved in metamorphism. The flow of water and cycling of weather patterns relate more to sedimentary processes, while evaporation and condensation pertain to hydrological cycles rather than the transformation of rocks under metamorphic conditions.