Earth’s Interior

The Science of Geology

• Geologists- scientists who study the forces that make and shape planet Earth.– They also:

• study the chemical and physical characteristics of rock.• map where different types of rock are found• describe landforms

• Rock- the material that forms Earth’s hard surface.• Geology- the study of planet of Earth. It began in

the late 1700s.

Is Change a Good Thing?

• Forces beneath the surface are constantly changing Earth’s appearance.

• The forces that change the Earth’s surface are divided into two groups:1. Constructive forces- shape the surface by building up mountains and landmasses

2. Destructive forces- slowly wear away mountains and eventually every other feature on the surface.

A Journey to the Center of the Earth

• As you start to travel beneath the surface the rock is cool for about 20 meters.

• Then the rock starts to get warmer.• The deeper you go the greater the

pressure.–More pressure because of the weight of the

rock above.– Pressure is the force pushing on a surface area.

A Journey to the Center of the Earth

• 3 main layers– Crust–Mantle – Core

The Crust

• Not this crust!

The Crust

• Crust- Earth’s solid and rocky outer layer.– This includes the land surface and the ocean floor. • Rocks, mountains, soil and water

– The crust ranges from 5-40 km thick. • The thinnest of all the layers.

– The crust beneath the ocean is called oceanic crust. • Consists mostly of basalt.

– Continental crust is mainly made up of granite.

The Mantle• A layer of hot rock.• 2,900 km thick• Pressure and temperature increase the deeper you go.

The Core

• The core is made up of two parts.– O U T E R C O R E - 2,250 km thick• L I Q U I D• A layer of molten metal

– I N N E R C O R E -1,200 km thick• S O L I D• The extreme pressure squeezes the atoms of iron and

nickel so much that they cannot spread out and become liquid.

• The outer and inner core together are just smaller than the E A R T H ’ S M O O N

Earth’s Magnetic Field• Currents in the liquid outer core cause the solid

inner core to spin.• The inner core spins inside Earth.• This movement causes Earth’s magnetic field.– A magnetic field is caused by moving electrical charges.

• This is what causes the compass needle to point north. It aligns with Earth’s magnetic north pole.

Who Went to the Center of the Earth?

• No one!• The extreme conditions

prevent us from going below the surface

• The deepest mine in the world (gold mine) is in South Africa.- 3.8 km– You would have to travel 1,600

times that (6,000 km) to reach Earth’s center.

So How Do We Know What is There?

• Scientists rely on indirect methods• They use seismic waves (similar idea to

knocking on a wall to listen for a change in sound if you were looking for a beam to nail a picture to).– A vibration that travels through Earth carrying

the energy released during an earthquake.– The speed of the seismic waves and the paths

they take reveal how the planet is put together.