What is a rock?
Introduction:
Rocks are one of the most basic and fundamental components of the Earth’s crust. They are made up of minerals or other organic matter that has been compacted and hardened over millions of years. In this lesson, we will examine what rocks are and how they are formed.
Key Concepts:
- Rocks are made up of minerals or other organic matter that has been compacted and hardened over time.
- There are three main types of rocks: igneous, sedimentary, and metamorphic.
- Each type of rock has unique characteristics that distinguish it from the others.
Igneous Rocks:
- Igneous rocks are formed from solidification of molten magma or lava.
- They can be classified as intrusive or extrusive depending on whether they form inside or outside of the Earth’s crust.
- Examples of igneous rocks include granite, basalt, and pumice.
Sedimentary Rocks:
- Sedimentary rocks are formed from the accumulation and lithification of sedimentary materials such as sand, mud, and organic matter.
- They can be classified as clastic, chemical, or organic depending on the type of sedimentary material involved.
- Examples of sedimentary rocks include sandstone, limestone, and coal.
Metamorphic Rocks:
- Metamorphic rocks are formed from the alteration of pre-existing rocks due to high temperatures and pressures.
- They can be classified as foliated or non-foliated depending on whether they have visible layers or not.
- Examples of metamorphic rocks include marble, slate, and schist.
Equations and Formulas:
- There are no specific equations or formulas related to the formation or classification of rocks.
Examples:
- A granite rock is an igneous rock that forms from the slow cooling of magma deep beneath the Earth’s surface.
- A sandstone rock is a sedimentary rock that forms from the accumulation and lithification of sand particles.
- A marble rock is a metamorphic rock that forms from the recrystallization of limestone under high heat and pressure.
References for Further Learning:
- Earth Science: Geology, the Environment, and the Universe textbook by Glencoe/McGraw-Hill.
- The Rock Cycle interactive activity on the National Geographic website.
- The Geological Society of America’s website, which provides information and resources about rocks and geology.
