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 (16th 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 24th, 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 Originate from the interior
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
Colliding
Subduction
Accretion
Spreading
Folds
Faults
Earthquakes
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
Weathering
Wind Erosion
Glacial Erosion
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
Evaporation – sun, changing liquid into vapor or gas
Condensation – excess water vapor changes into liquid form
Forms clouds
Precipitation – rain, snow, or sleet that sinks into the grounds and soon is evaporated again

52. Bodies of Salt Water (97%)
Oceans
Pacific
Atlantic
Artic
Southern
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