Florida Teacher Certification Examinations (FTCE) Subject Area Practice Test

Which type of rock is formed through the cooling and solidification of lava or magma?

1. Metamorphic

2. Igneous

3. Sedimentary

4. Foliated

The correct answer is: Igneous

The formation of igneous rock is a direct result of the cooling and solidification of either lava or magma. When magma, which originates from the molten material within the Earth's mantle, rises to the surface and erupts as lava, it cools quickly upon exposure to the atmosphere, solidifying into extrusive igneous rock. Conversely, if magma cools slowly beneath the Earth's surface, it forms intrusive igneous rock, characterized by larger crystals due to the extended cooling time. Understanding the features that differentiate igneous rocks helps clarify their classification in the rock cycle. Metamorphic rocks, for example, are produced when existing rocks undergo a transformation due to heat, pressure, or chemically active fluids, which is unrelated to the initial cooling process of molten material. Sedimentary rocks, on the other hand, are formed through the accumulation and compaction of mineral and organic particles, further differentiating them from igneous rocks. Foliated is a term that describes a texture in metamorphic rocks where minerals are aligned in bands, which again does not pertain to the cooling and solidification process that defines igneous rock formation.