Chapter 1: Section 1

Earth’s Interior

The Science of Geology, pg. 17

• Geologists are scientists who study the forces that make and shape planet Earth.

The Science of Geology, pg. 17

• Geology is the study of planet Earth and the rocks found on the surface.

The Science of Geology, pg. 17

• Geologists:– Study chemical and physical characteristics

of rock: material that forms Earth’s hard surfaces.

– Map where different types of rock are found on and beneath the Earth’s surface.

– Describe landforms (features formed in rock and soil by water, wind and waves).

– Search for clues about Earth’s history by studying processes that create Earth’s features.

Studying Surface Change

• Forces beneath the Earth’s surface constantly change Earth’s appearance.

• 2 forces that change the surface are:– Constructive Forces– Destructive Forces

Studying Surface Change

• Constructive Forces: Forces that shape the surface by building up mountains and landmasses (such as islands and continents).

Studying Surface Change

• Destructive Forces: Forces that slowly wear away mountains and other features on the surface (Example: When ocean waves wear away the shoreline).

• How old is Earth?• How has Earth’s surface changed

over time? • Why are there oceans, and how did

they form? • What’s INSIDE Earth?

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

Finding Indirect Evidence, pg. 18

• Since geologists cannot dig a hole to the center of the Earth and make direct observations (because of extreme temperature conditions) they rely on indirect methods of observations.

• FYI: The deepest level reached was at a gold mine in South Africa (Depth of 3.8km) You would need to travel 1,600 times that depth to reach the center of the Earth, or approximately 6,000km.

Finding Indirect Evidence, pg. 18

• Geologists use Seismic Waves: A vibration that travels through Earth carrying the energy released during an earthquake.

• They record the waves and study how they travel through Earth (speed, paths taken).

Finding Indirect Evidence, pg. 18

• These indirect observations allowed scientists to learn about the Earth’s interior:– It is made up of several layers. – Each layer surrounds the layers beneath

it (Similar to an onion).

A Journey to the Center of the Earth, pg. 19

• To get to the center of the Earth, you will travel through several different layers.

• The 3 main layers of the Earth’s Interior are:1. Crust2. Mantle3. Core• Each is made up of its own materials and

has its own conditions.

A Journey to the Center of the Earth, pg. 19

• Temperature: – On the surface of the Earth, the rocks

are cool– As you reach about 20m below they

become warmer. Every 40m from this point, the temperature rises 1oC for several km then continues to increase slow and steady

A Journey to the Center of the Earth, pg. 19

• Pressure is the force pushing on a surface or area.

– As you travel further below the Earth’s surface, the pressure increases.

The Crust, pg. 20

• The Crust is the layer of rock that forms Earth’s outer skin.

• This is where we find rocks, mountains, soil and water. It includes the dry land as well as the ocean floor.

The Crust, pg. 20

• The crust is the thinnest beneath the ocean and the thickest under mountains.

• Thickness averages at 32 kilometers thick. • The crust beneath the ocean is called

oceanic crust which has very dense rocks such as basalt; a dark dense rock with a fine texture.

Basalt

The Crust, pg. 20

• The crust that forms the continents is called continental crust which is made up of less dense rocks such as granite; a light colored, less dense rock.

Gran

ite

The Mantle• As you move beneath the crust you will

reach the Mantle made up of a layer of hot rock.

• Thickness is 2,900 kilometers and goes almost halfway to the center of the Earth.

• As you move towards the Earth’s center, the mantle is hotter and under increasing pressure.

• The mantle is soft, like tar and can bend, like plastic and can flow easily.

The Mantle

• The upper part of the mantle AND the crust together form the lithosphere, meaning “stone.” It is solid and rigid.

• Below the lithosphere, where you encounter the soft and bendable layer of the mantle, it is called the asthenosphere, meaning “weak.”

The Core, pg. 21

• 2 parts of the core: • Outer Core• Inner Core

• Combined they make up 1/3 of the Earth’s mass. But only 15% of its volume.

• Together they are slightly smaller than the moon.

• Temperature ranges from 2,0000C to 5,0000C, about the temperature of the sun’s surface.

The Core

• Outer Core:• Surrounds the inner core. • Layer of molten metal. • Thick liquid• A lot of pressure!

The Core

• Inner Core:• Dense ball of solid metal. • Extreme pressure squeezed atoms of iron and

nickel so much that they cannot spread out to become a liquid.

Earth’s Magnetic Field, pg. 24

• Currents in the liquid outer core force the solid inner core to spin slightly faster than the rest of the planet.

• The currents in the outer core creates Earth’s magnetic field, causing the planet to act as a giant magnet.