Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

What type of rock is Basalt classified as?

1. Intrusive igneous rock

2. Extrusive igneous rock

3. Metamorphic rock

4. Sedimentary rock

The correct answer is: Extrusive igneous rock

Basalt is classified as an extrusive igneous rock because it forms from the rapid cooling and solidification of lava that erupts onto the Earth's surface. When lava flows out during a volcanic eruption, it loses heat quickly as it comes into contact with the atmosphere or water, resulting in the formation of basalt. This rock is typically fine-grained due to the rapid cooling process, which does not allow large crystals to develop. Extrusive igneous rocks, like basalt, are characterized by their formation from volcanic activity, while intrusive igneous rocks form from magma that cools slowly beneath the surface, leading to larger crystal sizes. Metamorphic rocks are created through the alteration of pre-existing rocks due to heat, pressure, or chemically active fluids, and sedimentary rocks form from the accumulation and lithification of sediment. Each rock type has distinct formation processes, and understanding these processes is crucial for proper classification.