TeXes Science Practice Test

Which type of rock is formed through the process of high-pressure and high-temperature metamorphism?

1. Igneous

2. Sedimentary

3. Metamorphic

4. Volcanic

The correct answer is: Metamorphic

The formation of metamorphic rock occurs under conditions of high pressure and high temperature, generally within the Earth’s crust. During this process, existing rocks—either igneous or sedimentary—are subjected to these extreme conditions, which cause physical and chemical changes without the rock melting. In contrast, igneous rocks originate from the cooling and solidification of molten material, known as magma or lava. Sedimentary rocks, on the other hand, form from the accumulation and lithification of sediment or organic material. Volcanic is a term that typically describes the process associated with igneous rocks formed from lava flow, which is distinct from the metamorphic process. Metamorphic rocks exhibit characteristics such as foliation or banding due to the directional alignment of minerals that occurs during metamorphism, which is directly related to those high-pressure and high-temperature conditions. This explains why the correct answer focuses on metamorphic rock, as it is the only type that directly results from the metamorphic process described.