This week and next week we will study the different kinds of Rocks.

I will upload 2 videos and the lesson from the book to help you understand the lesson.

 What Are the Types of Rocks?

VOCABULARY

Igneous rock

Sedimentary rock

Metamorphic rock

Types of Rocks

Suppose you want to start a rock collection. How would you group the rocks? By color, by grain size, by whether they have layers? Rocks can look very different, but there are just three main types of rocks. The three types of rocks are grouped by how they form.

Igneous rock is a rock that was once melted and then cooled and hardened. Some igneous rocks cool quickly and look like glass. Other igneous rocks cool more slowly and have large grains.

Rock that forms from material that has settled into layers is called Sedimentary rock. The layers are squeezed together until they form rock.

The third type of rock is called metamorphic rock. Metamorphic rock is rock that has been changed by temperature and pressure.

How Rocks Form

The three types of rock form differently. Melted rock can reach Earth’s surface through a volcano. Then it cools and becomes igneous rock.

Sedimentary rock, by contrast, begins with the breaking of rocks. Wind and water break rock into bits. Then the wind and water carry the bits of rock and soil away. The bits settle into layers. After a long time, the layers harden into rock.

Metamorphic rock forms deep in Earth’s crust in yet another way. The pressure and temperature there change rock into metamorphic rock.

Wind and water break rock into small bits. Then wind and water carry away the bits of rock. Layers of these bits of rock form and, under pressure, become sedimentary rock.

  

    Wind and water break rock into small bits. Then wind and water carry away the bits of rock. Layers of these bits of rock form and, under pressure, become sedimentary rock.

Rock inside Earth softens from Earth’s high heat.Pressure in Earth’s crust then squeezes the rock.  The rock changes into metamorphic rock. The Rock Cycle Over time, one kind of rock can become any other kind. The process of rocks changing from one kind of rock to another kind of rock is called the rock cycle. The diagram on the right page shows this cycle. Wind and water break down all kinds of rocks to form sedimentary rocks. Any kind of rock that melts and cools can become an igneous rock. Any rock can end up in Earth’s crust and be pressed and heated. Then that rock can become metamorphic rock. The Rock Cycle Over time, one kind of rock can become any other kind. The process of rocks changing from one kind of rock to another kind of rock is called the rock cycle. The diagram on the right page shows this cycle. Wind and water break down all kinds of rocks to form sedimentary rocks. Any kind of rock that melts and cools can become an igneous rock. Any rock can end up in Earth’s crust and be pressed and heated. Then that rock can become metamorphic rock.