Unit 3 Dynamic Earth

1-2 What are the main parts of Earth? Lesson Summary • A sphere is a round, three-dimensional object; Earth is a sphere. • The lithosphere is the solid part of Earth; it includes the continents and the land under the oceans. • The hydrosphere is made of liquid water or ice; it includes the oceans, rivers, lakes, glaciers, and the polar ice caps. • The atmosphere is the envelope of gases surrounding the Earth; nitrogen and oxygen make up most of the atmosphere.

The Earth is divided into 4 layers 1. Crust (Lithosphere) 2. Mantle (Magma) 3. Outer Core 4. Inner Core

1-3 What is the structure of Earth? Lesson Summary • Earth has four layers; the crust, the mantle, the inner core, and the outer core. • The crust is the outer layer of Earth; it forms the upper lithosphere. • The layer of Earth beneath the crust is the mantle; more than two-thirds of Earth’s mass is in the mantle. • The core is the innermost layer of Earth; it has a liquid outer layer and a solid inner layer.

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.

Composition (make-up) Layer Description Composition (make-up) Physical Properties Crust (Lithosphere) Thinnest layer (5-100 km thick) Made of rock Rock Solid Mantle Thickest Layer just beneath the crust (2,900 km thick) Made of molten (liquid) rock – MAGMA More dense than the crust Hot molten rock 2/3 of Earth’s Mass MOVE Outer 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

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 Plates Type of Force Force Description Ridge Push Lava coming out of the mantle ‘pushes’ the plates apart View 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 Gravity View 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.

Fault Line

Google Earth

EARTHQUAKES An earthquake is the shaking of the Earth’s crust. The study of earthquakes is called Seismology The instruments used to measure and display an earthquake’s magnitude (strength) is a seismometer and a 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

Recent Earthquakes http://earthquake.usgs.gov/earthquakes/map/

Three Types of Plate Boundaries Convergent Divergent Transform This motion creates: Volcanoes Seafloor spreading Ridges Mountains 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 Safety Before 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 Safety During the shaking: Get under a table Get in a doorway Stay away from objects that may fall on you

Earthquake Safety After the shaking: Get away from danger Go to your previously appointed emergency location Do not go back indoors until advised