AFOQT Practice Test

Metamorphic rock is a result of what processes acting on existing rock?

1. Heating, cooling, and forming new minerals

2. Melting, solidifying, and crystallizing

3. Heat, pressure, or chemical reactions

4. Weathering, erosion, and transport

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

Metamorphic rock forms primarily due to the processes of heat, pressure, and chemical reactions acting on pre-existing rocks. This transformation occurs deep within the Earth's crust, where temperatures and pressures are significantly higher than at the surface. During this metamorphic process, the original minerals in the rock change, and new minerals can form as a result of the altered conditions. Heat can cause minerals to become unstable, leading to recrystallization and the development of new textures. Pressure can cause the minerals to align or fold, resulting in distinct layering or foliation. Additionally, chemical reactions can occur when mineral components mix with fluids, further transforming the rock. This clarification highlights how these specific processes contribute to the formation of metamorphic rocks, distinguishing them from processes such as weathering and erosion, which relate to sedimentary rock formation, or melting and solidifying, which pertain to igneous rocks.