Why It Matters: Rocks and the Rock Cycle

Identify processes of the rock cycle and the different rock types associated with each step.

Introduction

In this section we will learn about the rock cycle and the different types of rocks. Please watch this short video for an introduction:


As you can see, the rock cycle is never ending. The video explained how rocks change from one rock type to another, and—just as important—it showed the processes that cause those changes.

Learning the rock cycle and understanding the processes involved helps all of us. For example, you saw in the video how all rocks are eroded into fine particles. This is how soil forms, through the breakdown of rocks. We need soil to survive—imagine trying to grow vegetables without it. This is an immediate connection to the food chain. The rock cycle also gives scientists and engineers an idea on where energy sources (mainly fossil fuels, which are found only in sedimentary rock) and building materials such as marble or granite may be located. We will see throughout the course how this cycle plays into just about every aspect of geology.

Here’s a visual representation of the rock cycle:

Representation of the rock cycle in a rough circle. Metamorphic rocks lead to erosion or melting. Melting leads to magma, which leads to crystallization (freezing of rock), which leads to igneous rocks. Igneous rocks lead to metamorphic rocks, melting, or to erosion. Erosion leads to sedimentation, which leads to sediments and sedimentary rocks. Sedimentary rocks leads to erosion or tectonic burial and metamorphism. Tectonic burial and metamorphism leads to metamorphic rocks.

As you continue through the module, refer back to this image. Remember that all the processes of the rock cycle are interconnected.

Learning Outcomes

  • Identify igneous rocks and the steps of the rock cycle related to their formation.
  • Identify sedimentary rocks and the steps of the rock cycle related to their formation.
  • Identify metamorphic rocks and the steps of the rock cycle related to their formation.