Which type of rock can be foliated?
A. Metamorphic rock
B. Igneous rock that cools quickly
C. Igneous rock that cools slowly
D. Sedimentary
A. Metamorphic rock
The correct answer is A. Metamorphic rock.
The correct answer is A. Metamorphic rock. Metamorphic rocks are formed by the transformation of pre-existing rocks through heat, pressure, or chemical processes deep within the Earth's crust. During this transformation, the minerals in the rock can rearrange themselves, causing the development of a banded or layered texture, known as foliation. Foliation is a characteristic feature of many types of metamorphic rocks, such as gneiss, schist, and slate.
To arrive at this answer, one could start by recalling that the term "foliation" refers to the arrangement of minerals in a parallel or layered fashion within a rock. This knowledge would help eliminate options B and C, which describe types of igneous rocks that do not typically develop foliation. Igneous rocks form from the solidification of molten magma or lava, and their texture is predominantly determined by how quickly they cool – with quick cooling resulting in fine-grained or glassy textures, and slow cooling leading to the development of coarse-grained textures.
One could then consider option D, which describes sedimentary rocks. Sedimentary rocks are formed by the deposition and burial of sediments, such as sand, mud, or organic matter, which eventually become compacted and cemented together. While sedimentary rocks can have various textures, they generally lack the preferred orientation of minerals associated with foliation. Therefore, option D can also be ruled out.
By process of elimination, the correct answer is A. Metamorphic rock, as it is the only option that aligns with the characteristic feature of foliation.