The Rock Cycle for Middle School Science

Feb 20

3 min read

The rock cycle describes how rocks change on Earth. Rock can transition between sedimentary, igneous, and metamorphic rock as it moves through the Earth's crust. This blog post will help students understand and remember all the different parts of the rock cycle.

If you would like a copy of the picture book, you can get it along with the reading passage, flashcards, and comprehension activities at Teachers Pay Teachers.

The Rock Cycle

The rock cycle describes how rocks change as they move through the environment. There are three main types of rocks on Earth: igneous rocks, sedimentary rocks, and metamorphic rocks. Through the rock cycle, these rocks transform into each other.

Like the water cycle, the rock cycle does not have a beginning, but the first rocks on Earth appeared when the hot liquid lava that made up the entire surface of the forming Earth cooled. Today, cooling magma continues to create igneous rocks.

When wind, water, plants, and animals weather and erode igneous rocks, they become sediments. Sediments are small pieces of rocks, minerals, plants, or animals. For example, sand is a sediment. Over time, sediments build up into many layers. The top layers put immense pressure on the bottom layers. Compaction and cementation turn the sediments into sedimentary rock. Compaction is the process of individual sediments being squeezed together, and cementation is the process of dissolved minerals gluing the sediments into rock as water moves through the layers.

Over millions of years, the movement of tectonic plates can force rocks from the surface of the Earth underground. If sedimentary rock or igneous rock gets buried deep under Earth's surface, the high temperatures and pressure turn them into metamorphic rock.

Weathering and erosion, as well as the movement of tectonic plates, eventually bring metamorphic rock to the surface. Once at the surface, weathering can turn it into sediments that will someday become sedimentary rock.

If any of the rocks are forced too deep underground, the heat from the mantle will melt them. We call melted rock magma when it is underground. When it reaches the surface, we call it lava. When the magma or lava cools, it becomes igneous rock.

Through the rock cycle, any type of rock can become another type of rock. A sedimentary rock deep underground can become metamorphic rock that melts and then cools to become igneous rock. Another sedimentary rock can be weathered into sediments that someday become a new sedimentary rock.

Some parts of the rock cycle happen quickly. In Hawaii, you can watch as lava flowing from a volcano cools into igneous rock. However, most of the rock cycle is so unbelievably slow that we can't see it. Metamorphic rocks discovered in Greenland are 3.8 billion years old.

The rocks that make up the continental crust are much older than the rocks that make up the oceanic crust deep underwater because continental crust is less dense than oceanic crust. Under the ocean, the dense oceanic crust is forced into the mantle at subduction zones. New oceanic crust replaces the old crust at mid-ocean ridges where magma from deep within the crust pushes into the ocean floor and cools into igneous rock.

Like the rocks of the oceanic crust, the rocks of the continental crust are moving between the three types of rock; they just do it much more slowly.

Rock Cycle Flashcards

Understanding the rock cycle is just one part of learning the steps in the rock cycle. Students also have to practice remembering the vocabulary and the information. Flashcards are incredibly helpful for this task. Printed and digital flashcards make a great addition to your classroom routine. You can get these flashcards on the rock cycle at Teachers Pay Teachers.

You can also see and practice all of the flashcards right here!

Rock Cycle Videos

I like to use videos to teach new concepts because students can use visual cues to support their learning. Here are some of my favorite videos on the rock cycle.