Rocks

Rocks are solid, naturally occurring substances made up of one or more minerals. They are classified into three main types based on how they are formed: igneous, sedimentary, and metamorphic.

Igneous Rocks

Igneous rocks are formed from the solidification of molten rock material. This can happen either below the Earth's surface (intrusive) or on the surface (extrusive). Examples of igneous rocks include granite, basalt, and obsidian.

Sedimentary Rocks

Sedimentary rocks are formed from the accumulation and compaction of sediments. These sediments can be made up of pieces of other rocks, minerals, or organic materials. Examples of sedimentary rocks include limestone, sandstone, and shale.

Metamorphic Rocks

Metamorphic rocks are formed from the alteration of existing rock through heat, pressure, or chemically active fluids. This process causes the original rock to recrystallize into a new rock with different properties. Examples of metamorphic rocks include marble, slate, and quartzite.

Study Guide

1. What are the three main types of rocks? Provide examples of each.
2. How are igneous rocks formed? Explain the difference between intrusive and extrusive igneous rocks.
3. Describe the formation process of sedimentary rocks. What are the main types of sediments that can contribute to their formation?
4. What causes the formation of metamorphic rocks? Provide examples of common metamorphic rocks.
5. Explain the rock cycle and how each type of rock can transform into another over time.