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Chapter 2 The Earth. Section I. Planet Earth  What do you know about the Solar System?

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Presentation on theme: "Chapter 2 The Earth. Section I. Planet Earth  What do you know about the Solar System?"— Presentation transcript:

1 Chapter 2 The Earth

2 Section I. Planet Earth  What do you know about the Solar System?

3 A. Our Solar System  The sun is at the center of our Solar System  Sun creates a strong pull of gravity  Keeps objects such as Earth revolving around the Sun

4 Our Solar System  Revolution – in astronomy, the Earth’s yearly trip around the sun  365 ¼ days  Why is the ( ¼ ) important to know??  Rotation – the Earths daily trip turning on its axis  How long is a day?

5 In history….  People believed that the solar system revolved around Earth  Geocentrism  Connected to religion  But it was Galileo (16 th century) that actually fought for the now accepted theory that we were the ones moving  Heliocentrism

6 What’s the idea behind the theories?  Why would people think we were geocentric??  Which theory would you side with if you had to choose?  What would happen without the sun?


8 The “Classical” Planets: Neighbors in Space  Before it was believed we had nine planets now we just classify eight  Inner Planets (Terrestrial)  Mercury  Venus  Earth (only one with sustainable life)  Mars

9 The “Classical” Planets: Neighbors in Space  Outer Planets (Gas Giants)  Jupiter  Saturn  Uranus  Neptune  All have moons except Mars & Venus  There are also asteroids, comets and meteoroids

10 Pluto……..planet??  Discovery Channel, August 24 th, 2006  [Much-maligned Pluto doesn't make the grade under the new rules for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a... nearly round shape, and has cleared the neighborhood around its orbit.“]  [Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.]

11 B. Getting to know the Earth  The earth is divided into categories  Hydrosphere – part of Earth made up of oceans, lakes, rivers, and other bodies of water  Lithosphere – part of Earth made up of continents and islands  Atmosphere – a layer of gases that surrounds the Earth  Biosphere – the part of the Earth that supports life

12 Hydrosphere = WATER  Earth is 70% water

13 Lithosphere = Land  Earth is 30% land

14 Atmosphere = Air  Above earth’s surface you have a layer of gases  78% nitrogen, 21% oxygen and the rest argon and other gases  Our natural vegetation is essential to the recyclement of our oxygen

15 Biosphere = life  The part of earth that supports life  Life outside of the biosphere only exist with mechanical life support system  Space shuttle

16 Air + Land + Water = Biosphere!  Bio=life! Hence, Biology….

17 C. Landforms  Natural features of the earth’s surface that vary in shape and elevation  4 major landforms-  Mountains  Hills  Plateaus  Plains Also have valleys, canyons, and basins All contain rivers, lakes and streams

18 Underground Landforms  Landforms underwater are as diverse as those found on dry land  Range from flat plains to mountain ranges, cliffs, valleys and deep trenches

19 Earth’s most visible landforms  From space the most visible landforms are the 7 continents  Australia  Antarctica  Europe  Asia  North America  South America  Africa **** Locate continents on your map ****

20 Continental Shelf  Part of a continent that extends underwater


22 Long narrow underground canyon (Pacific Ocean)

23 Section II. Forces of Change  How does earth change?  What processes are responsible for such changes?

24 Forces of Change  On the surface  Wind, water, etc  Originate from the interior  Volcanic eruptions, earthquakes, etc

25 Earth’s Structure  The earth is composed of three layers

26 Core  Inner core is made up of iron and nickel under enormous pressure  Outer layer is liquid made up of melted iron and nickel

27 Mantle  Thick layer of hot dense rock  Mixture of elements that continually rises, cools, sinks, warms up and rises again  Responsible of 80% of heat generated from earth’s interior

28 Crust  Broken up into more than a dozen great slabs of rock called plates that rest (float) on a partially melted layer in the upper mantle  Carry the earth’s oceans and continents

29 Continental Drift Theory Pangaea  Theory that all the continents were once joined and slowly started to drift apart

30 Plate theory “Continental Drift”  Pangaea – a gigantic supercontinent that eventually broke apart (drifted) into smaller continents due to plate movement

31 Crust=Plates

32 Plate Tectonics  Plates are continually moving  At times they may crash, pull apart, grind or slide past each other  Constantly changing the face of the planet  They push up mountains, create volcanoes, and produce earthquakes  Theory: heat rising from the core create slow-moving currents within the mantle which then shift the plates around

33 Crust=Plates

34 Internal forces of change 1. Colliding 2. Subduction 3. Accretion 4. Spreading 5. Folds 6. Faults 7. Earthquakes 8. Volcanic Eruptions

35 1. Colliding  Giant continental plate collide  Creates mountains  Himalayas

36 2. Subduction  A heavier sea plate dives beneath the lighter continental plate  Plunging into the earth’s interior, the sea plate becomes molten material  Then as magma it bursts through the crust to form volcanic mountains  Andes

37 3. Accretion  Pieces of earth’s crust come together slowly as the sea plate slides under the continental plate  Creates underwater mountains with steep sides and sharp peaks  Creates new land often island chain at the boundary

38 4. Spreading  Sea plates pull apart  Deep cracks (rift) allow magma from within the earth to well up between the plates  Magma hardens to build undersea volcanic mountains or ridges  Spreading keeps Europe and N. Ame apart

39 5. Folds (bends)  Moving plates squeeze the earth’s surface until it buckles or creates folds in layers of rock

40 6. Faults  Plates grind or slide past each other creating cracks in earth’s crust  When land can no longer be folded the earth’s crust cracks and breaks into huge blocks  Small tremors occur  San Andres Fault in CA

41 7. Earthquakes  Sudden, violent movements of plates along a fault line  Dramatically change the surface of the land and the floor of the ocean  Happen when different plates meet each other. Tension builds up as the plates stick. The strain becomes so intense that the rocks suddenly snap and shift. This releases stored up energy along the fault. Eventually the ground trembles as sends shock waves which are felt

42 Ring of Fire  Earthquake and volcano zone surrounding the Pacific Ocean  Boundary where the plates that cradle the Pacific meet the plates that hold the continents surrounding the ocean

43 8. Volcanoes  Volcanoes are mountains formed by lava or magma that breaks through the earth’s crust  Often rise along plate boundaries where one plate plunges beneath another  In such a process the rocky plate melts as it dives downward into the hot mantle. Pressure builds, a funnel is created and hot magma rushes to the surface. The lava will eventually create a volcano

44 Volcanoes  As a moving plate passes over these hot spots, molten rock flowing out of the earth’s surface may create volcanic island chains  Hawaiian Islands  Molten rock may also heat underground water causing hot springs or geysers  Yellowstone

45 External Forces of Change  Wind and water change the earth’s surface (two processes)  Weathering – process that breaks down rocks on the earth’s surface into smaller pieces  Erosion – wearing away of the earth’s surface by wind, glaciers, and moving water 1. Weathering 2. Wind Erosion 3. Glacial Erosion 4. Water Erosion

46 Weathering  Either physical weathering or chemical weathering  Physical – when large masses of rock are physically broken down into smaller pieces  Water seeps into the cracks in a rock and freezes, then expands and causes the rock to split  Chemical – changes in the chemical makeup of rocks (transforming their minerals or combining them)  Water mixed with carbon dioxide from the air easily dissolves certain rocks such as limestone

47 Wind Erosion  Movement of dust, sand, and soil from one place to another  Can be devastating or beneficial  Dust Bowl  China Yellow River basin is thickly covered with loess (fertile yellow-gray soil deposited by wind)

48 Glacial Erosion  Glaciers – large bodies of ice that slowly move across the earth’s surface  Glacial movements change the landscape by destroying forests, carving our valleys, etc  However, when glaciers melt and recede they leave behind large pules of rocks and debris (moraines)  Moraines can form long ridges of land or create glacial lakes

49 Water Erosion  Most significant cause of erosion  Fast moving water – rain, rivers, streams, and oceans – cuts into the land wearing away the soil and rock  The resulting sediment (small particles of soil, sand and gravel) act like sandpaper and cut away at land  Grand Canyon

50 Section 3 – Earth’s water  Hydrosphere!!  Almost all of the hydrosphere is salt water found in the oceans, seas and seawater lakes  The remainder is freshwater found in lakes, rivers, and springs

51 Water Cycle  Regular movement of water through 1. Evaporation – sun, changing liquid into vapor or gas 2. Condensation – excess water vapor changes into liquid form 1. Forms clouds 3. Precipitation – rain, snow, or sleet that sinks into the grounds and soon is evaporated again

52 Bodies of Salt Water (97%)  Oceans 1. Pacific 2. Atlantic 3. Artic 4. Southern 5. Indian  Seas, Gulfs, and Bays  Desalination – conversion saltwater into freshwater

53 Freshwater (3%)  Lakes, Streams, and Rivers  Groundwater – freshwater that lies beneath the earth’s surface  Comes from rain and melted snow that filter through the soil and from water that seeps into the ground from lakes and rivers  Can use wells to tap into freshwater  Aquifer – underground porous rock layer saturated with water in the form of streams

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