Unit 3Dynamic Earth

The Earth is divided into 4 layers

1. Crust (Lithosphere) 2. Mantle (Magma) 3. Outer Core 4. Inner Core

Layers of the Earth (List the 4 layers of the earth, choose a color for each layer

and color diagram the appropriate color)

Why does the Earth have layers?

The layers formed because of their different densities.

The less dense material is found in the crust.

The more dense compounds sank to the center of Earth.

Crust

Outermost layer Thinnest layer (5-100 km thick) Two types: Continental and Oceanic Click here to see the 2 types of crust

Oceanic and Continental Crust

Mantle

Just beneath crust Contains most of Earth’s mass (67%) Thickest layer (2900 km thick) Hot, gooey layer made of magma (liquid

rock – molten rock)

Outer Core

Hot liquid Iron 2,200 km thick

Inner Core

Solid Iron/Nickel (metal) 1250 km thick

Earth’s Layers The crust is also known as the lithosphere. The broken sections of the crust are

referred to as plates (tectonic). These plates fit together along Earth’s

surface like a puzzle. The plates move along the surface very

slowly. The upper part of the mantle acts like a

plastic and is called the asthenosphere. It allows the plates to move.

Layer Description Composition (make-up)

Physical Properties

Crust (Lithosphere)

Thinnest layer (5-100 km thick)

Made of rock • Rock• Solid• Thinnest

layerMantle Thickest Layer

just beneath the crust(2,900 km thick)

Made of molten (liquid) rock – MAGMAMore dense than the crust

• Hot molten rock

• 2/3 of Earth’s Mass

• MOVEOuter Core Liquid layer of

the core(2,200 km thick)

Hot liquid iron • Liquid

Inner Core Solid layer of the core (METAL)(6,380 km below surface)

Solid iron and nickel

• Solid

Tectonic Plates

• Plate tectonics is the theory that the lithosphere is divided up into plates that move along the asthenosphere. (upper part of the mantle)

Three types of Plate Boundaries• 1. Convergent – where two plates are

colliding• 2. Divergent – where two plates are

separating• 3. Transform – where two plates slide

against each other

Convergent Boundaries

Divergent Boundary

Transform Boundary

Wegener’s Hypothesis of Continental Drift

• Continental Drift – is the hypothesis that the continents once formed a single continent called Pangaea. This continent broke up and the pieces have moved to their present locations.

Evidence that helps support Continental Drift

Similar findings on opposite sides of the Atlantic include:• Fossils• Plants• Mountain Ranges• Matching Rock Types

Movement of Tectonic Plates• What causes the tectonic plates to

move?Convection Currents

• Convection – the movement of thermal energy through a fluid.

Hottest magma rises Cooler magma sinks

Forces that move Tectonic PlatesType of Force

Force Description

Ridge Push Lava coming out of the mantle ‘pushes’ the plates apartView Ridge Push

Convection Hot liquid rock rises and cooler liquid rock sinks causing the crust to go away from the ridge.

Slab pull Oceanic Crust slides downward because of the force of GravityView Slab Pull

Deformation of the Earth’s Crust

• Deformation – Shape of rock changes (folds).

• Compression – Stress that occurs when forces act to squeeze an object.

• Tension – Stress that occurs when forces act to stretch an object.

Types of stress that deform rock:

• Folding – the bending of rock layers

• Faulting – the surface along which rocks break and slide past each other.

http://geology.com/articles/images/san-andreas-fault-map.jpg

• Fault Line

Google Earth

EARTHQUAKES• An earthquake is the shaking of the Earth’s

crust.

• The study of earthquakes is called Seismology

• The instrument used to measure an earthquakes magnitude (strength) is a seismometer and seismograph

Seismometers and Seismographs

EARTHQUAKE DAMAGE

EARTHQUAKES

• Earthquakes occur along PLATE BOUNDARIES (edges of the crustal plates)

• The most active earthquake zone is along the pacific ocean, also known as THE RING OF FIRE.

EARTHQUAKES

Three Types of Plate Boundaries

• Convergent

Mountains

This motion creates:

• Divergent • Transform

VolcanoesSeafloor spreadingRidges

Earthquakes

Seismic Waves• When an earthquake occurs it produces

vibrations, also known as seismic waves.

• Seismic waves are the reason we know the interior of the Earth.

Seismic Waves

• Speed: FAST Speed: SLOW

Shadow Zones• The solid core of the Earth blocks and bends

the vibrations from an earthquake from reaching the other side of the Earth.

• P-waves can travel through the interior of the earth

• S-waves can not pass through the liquid portions of the earth.

Measuring Earthquakes• Richter Scale – measures the magnitude

(strength) of the earthquake from 1 to 10.

• Mercalli Scale – measures the amount of damage done from an earthquake from I-XII.

Earthquake SafetyBefore the shaking:

• 1. Prepare emergency kit– Water– First Aid Kit– Radio / Batteries– Canned food / Can opener

• 2. Prepare escape route

• 3. Home Safety Plan– Remove objects from high shelves

Earthquake SafetyDuring the shaking:

1. Get under a table

2. Get in a doorway

3. Stay away from objects that may fall on you

Earthquake SafetyAfter the shaking:

1. Get away from danger

2. Go to your previously appointed emergency location

3. Do not go back indoors until advised