Soil Rocks and

Minerals4th Grade Science

How was the Earth’s Layers formed?What does the formation of the Earth have to do with rocks?

Crust- the rigid, rocky outer surface of the Earth, composed mostly of basalt and granite. The crust is thinner under the ocean.

Mantle-a rocky layer located under the crust – it is composed of silicon, magnesium, iron, aluminum, and calcium. Convection (heat) currents carry heat from the hot inner mantle to the cooler outer mantle.

Outer core- the molten iron-nickel layer that surrounds the inner core.

Inner core- the solid iron-nickel center of the Earth that is very hot and under great pressure

Comparing the layers of Earth to an apple

Apple Peel = Crust

Fruit = Mantle

Core = Outer Core

Seeds = Inner Core

Layers of the Earth

What are Minerals?

Many properties can help identify minerals and rocks.

Minerals can be identified by:• Hardness• Streak• color

Rocks can be identified by:• Texture• Minerals they are made of• How easily they crumble

A mineral is a solid object found in nature that has never been alive.

Properties of Minerals

Minerals are identified by their properties or characteristics. Some of the properties used to identify minerals are:

• Color• Streak• Luster• Hardness• Magnetism

Hardness is the measure of how difficult it is for a mineral to be

scratched.

Mohs Scale

What is a rock?

A rock is a naturally formed solid made of one or more minerals.

What are the three types of rocks?

Rocks can be divided into three broad categories- igneous, metamorphic, and sedimentary.

“Layer” your brain with

SEDIMENTARY ROCKS!

sedimentary rock- rock formed from material that has settled into layers

Wind and water carry small bits of rock. Layers of these bits of rock form and, under pressure, become sedimentary rock. Most sedimentary rocks are formed from layers of sediments that have been compressed under water for long periods of time.

“Fire up” your knowledge of

IGNEOUS ROCKS!

What is a Volcano?

Igneous rock- rock that was once melted and then

cooled and hardened

Volcanoes bring melted rock (magma) to the surface, where it cools. The cooled rock is igneous.

Igneous rocks or “fire” rocks are formed from hot molten material called magma.

“Change” your thoughts aboutMETAMORPHICROCKS!

metamorphic rock- rock that has been changed by temperature and pressure

Rocks inside the Earth soften from Earth’s high temperature. Pressure inside Earth then squeezes the rock. The rockchanges into metamorphic rock. Metamorphic means to change form. Metamorphic rocks are formed inside the earth.

The Rock Cycle