rocks

Rocks are everywhere.

The crust of the earth is made of rock.

When magma cools, it forms intrusive igneous rock

Intrusive igneous rock cools slowly and usually has large grains. .

gabbrogranite

When lava cools, extrusive

igneous rock is formed.

Extrusive igneous rock cools quickly and usually has small grains.

basalt pumice

Some extrusive igneous rocks cool so fast, they

have no grains at all!

obsidian (volcanic glass)

Rivers can carry sediment that piles up under water.

The layers pile up and eventually become hardened into rock

Sedimentary rocks often look like glued together rocks, pebbles, or sand.

sandstone conglomerate

Some sedimentary rock forms when water evaporates and minerals are left behind.

Halite (salt) and gypsum are formed

this way.

Fossils are often found in sedimentary rocks.

Plants & animals are caught in the layers of sediment and leave an imprint in the rock.

Fossils tell us a lot about things that lived long ago.

Metamorphic rock is rock that has been changed by heat

and pressure.

.

Heat & pressure can change sandstone into

quartzite.

Granite can become gneiss,

…and shale can become schist!

But rocks don’t always stay the same. Any kind of rock can change into

another kind of rock.

Any rock that weathers into sediment can be pressed and cemented. It becomes sedimentary rock.

Any rock that is melted, Any rock that is melted, can cool off and can cool off and

become igneousbecome igneous rock. rock.

With enough pressure and lots of heat, any rock can

change and become metamorphic rock.

This pattern of This pattern of changing rock is changing rock is

called the…called the…

This changing is called the rock cycle

REVIEWREVIEW

1. Rocks are made of minerals.1. Rocks are made of minerals.

2. There are 3 kinds of rocks.2. There are 3 kinds of rocks.

3. Rocks made from cooled lava 3. Rocks made from cooled lava or magma are igneous.or magma are igneous.

4. Sedimentary rocks are made of 4. Sedimentary rocks are made of layers of sediments that have layers of sediments that have been cemented together.been cemented together.

5. Metamorphic rocks have been 5. Metamorphic rocks have been changed with heat and changed with heat and pressure.pressure.

6. All rocks can change in the 6. All rocks can change in the rock cycle.rock cycle.