1. CHAPTER 1 Introduction to Planet “Earth”
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CHAPTER 1 Introduction to Planet “Earth”

2. Overview The world ocean is the most prominent feature on Earth.
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The world ocean is the most prominent feature on Earth.
Oceans cover 70.8% of Earth’s surface.
The origin and development of life on Earth is connected to the ocean.
The oceans have a long history on Earth.

3. Earth’s Oceans Earth has one ocean.
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Earth has one ocean.
It is divided into four principle oceans, and one other.
Pacific Ocean
Atlantic Ocean
Indian Ocean
Arctic Ocean
Southern, or Antarctic Ocean

4. Ocean Size and Depth
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5. Earth’s Oceans Pacific Ocean World’s largest ocean
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Pacific Ocean
World’s largest ocean
Accounts for more than half of Earth’s ocean space
World’s deepest ocean
Earth’s largest geographic feature
Named in 1520 by Ferdinand Magellan

6. Earth’s Oceans Atlantic Ocean Indian Ocean
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Atlantic Ocean
Half the size of the Pacific Ocean
Shallower than the Pacific Ocean
Separates the Old World from the New World
Indian Ocean
Smaller than the Atlantic Ocean
Similar depth as the Atlantic Ocean
Primarily in the Southern Hemisphere

7. Earth’s Oceans Arctic Ocean Southern Ocean or Antarctic Ocean
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Arctic Ocean
Seven percent the size of the Pacific Ocean
Shallowest world ocean
Permanent layer of sea ice a few meters thick
Southern Ocean or Antarctic Ocean
Circumnavigates Antarctica
Is really the parts of the Pacific, Atlantic, and Indian Oceans that lie south of 50° S latitude

8. The Seven Seas Smaller and shallower than oceans Salt water
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Smaller and shallower than oceans
Salt water
Usually enclosed by land
Sargasso Sea defined by surrounding ocean currents
Directly connected to the ocean

9. The Seven Seas
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Before the 15th Century, Europeans considered the seven seas to be the following:
Red Sea
Mediterranean Sea
Persian Gulf
Black Sea
Adriatic Sea
Caspian Sea
Indian Ocean

10. Comparing Oceans to Continents
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Average ocean depth is meters (12,234 feet)
Average continental elevation is 840 meters (2756 feet)
Deepest ocean trench is the Mariana Trench at 11,022 meters (36,161 feet)
Highest continental mountain is Mt. Everest at 8850 meters (29,935 feet)

11. Early Exploration of the Oceans
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Early “explorers” used boats to seek new fishing grounds for food.
The ocean facilitated trade and interaction between cultures.

12. Pacific Navigators
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The peopling of the Pacific Islands required extensive travel in open boats and exceptional navigation skills.
It was difficult because islands are widely scattered.
Used an understanding of natural phenomena to navigate

13. Ancient Polynesian Explorations and Discoveries
The significance of Polynesian seafaring is that it is the earliest known regular, long distance, open ocean seafaring beyond sight of land.
It’s estimated that it took more than 1000 years for the area to be fully settled. But had been so for hundreds of years when the first Europeans arrived.

14. Pacific People
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No written records exist of Pacific human history before the 16th Century.
Archeological evidence suggests island occupation by people from New Guinea as early as 4000–5000 B.C.
Polynesians reached nearly all the Pacific islands by about 1200 AD
Thor Heyerdahl sailed on a balsa raft – the Kon Tiki – to demonstrate migration of South Americans to Pacific Ocean islands.

15. Polynesian Stick Chart
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16. Chinese Explorations and Discoveries
Although science and exploration lay idle in Europe during the Middle Ages, that wasn’t the case in China.
Among many important contributions in that era, the Chinese were responsible for inventing the magnetic compass.
Shipbuilding: central rudders and watertight compartments.

17. Chinese Explorations and Discoveries
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Chinese Explorations and Discoveries
Seven voyages from 1405 to 1433
The fleet consisted of giant nine-masted junks
Escorted by dozens of supply ships, water tankers, transports for cavalry horses,
and patrol boats.
The armada's crew totaled more than 27,000 sailors and soldiers.
The largest of the junks were said to be over 400 feet long and 150 feet wide.
(The Santa Maria, Columbus's largest ship, was a mere 90 by 30 feet and his
crew numbered only 90.)

18. Chinese Explorations and Discoveries
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Chinese Explorations and Discoveries
Zheng He
Zheng He, was a mariner, explorer, diplomat, and fleet admiral during China's early Ming dynasty.
Exploration took place half a century before the first Europeans, rounded the tip of Africa in Portuguese caravels, and "discovered" the Indian Ocean.

19. European Navigators
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Phoenecians – first from Western Hemisphere to develop navigation arts
Navigated circa 2000 B.C.
Explored Mediterranean Sea, Red Sea, and Indian Ocean
First circumnavigation of Africa
Reached the British Isles

20. Ancient Phoenician Explorations and Discoveries
Phoenicia was an ancient civilization centered in the north of ancient Canaan, with its heartland along the coast of modern day Lebanon, Syria and northern Israel. Phoenician civilization was an enterprising maritime trading culture that spread across the Mediterranean during the first millennium BC, between the period of 1200 BC to 900 BC.

21. Ancient Phoenician Explorations and Discoveries

22. Ancient Phoenician Explorations and Discoveries
The ancient Phoenicians were among the most important early Western seafarers.
Traveled great distances for their day.
Established the first trade routes throughout the Mediterranean and as far north as Great Britain.
They steered at night by observing the constellations and the north star (Polaris, 430 l.y.a.) – in the ancient world, the north star was called the Phoenician Star. This is one of the earliest references to using the North Star for navigation.

23. European Navigators Greek Pytheas
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Greek Pytheas
Sailed northward using a simple method to determine latitude in 325 B.C.
Navigated using the North Star
Eratosthenes determined Earth’s circumference fairly accurately.

24. Ancient Greek Explorations and Discoveries
The Greek Pytheas noted that he could predict the tides in the Atlantic based on the phases of the moon.
About 150 years later, Eratosthenes ( B.C.) calculated the Earth’s circumference and invented the first lattitude/longitude system – a system of imaginary lines on the Earth, used for navigation and mapping.
Hipparchus invented a better system – the one used today – later.

27. The Latitude/Longitude System
One of the Greeks’ primary contributions to oceanography and seafaring is the latitude/longitude system.
Latitude lines run east-west and longitude lines run north-south.
Because they run around the sphere of the Earth, they are numbered in degrees. For further accuracy, degrees are numbered into 60 minutes and minutes into 60 seconds like time.

28. Latitude Lines

29. Longitude Lines

30. Prime Meridian and Equator
Longitude lines begin at one pole and end at the other. Sometimes called meridians, the 0⁰ meridian runs through the Royal Naval Observatory in Greenwich, England.
This is called the Prime Meridian. Directly on the other side of the world is the 180⁰ meridian.
If you are looking north, the meridians on the right of the prime meridian are called east longitude all the way to the 180⁰ meridian.

32. Let’s apply what we just learned to find the wreck of the Titanic!!!
49⁰ 56’ 49’’ W, 41⁰ 43’ 57’’ N

33. Did you navigate correctly?
49⁰ 56’ 49’’ W, 41⁰ 43’ 57’’ N

34. Europeans Herodotus produced inaccurate world map around 450 B.C.
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Herodotus produced inaccurate world map around 450 B.C.
Claudius Ptolomy produced fairly accurate world map around 150 A.D.
Erroneously updated Eratosthenes’ original circumference estimation, later causing Christopher Columbus to believe he had reached Asia

35. The Middle Ages Arabs dominant navigators in the Mediterranean Sea
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Arabs dominant navigators in the Mediterranean Sea
Traded extensively with East Africa, India, and Southeast Asia
Learned to use Indian Ocean monsoon winds for travel

36. The Middle Ages Vikings explored North Atlantic Ocean
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Vikings explored North Atlantic Ocean
Settled Iceland and Greenland in 9th and 10th centuries A.D.
Leif Eriksson designated part of eastern Canada Vinland (now Newfoundland) in 995 A.D.
Greenland, Vinland settlements abandoned by 1450 A.D. due to climatic cooling

37. Viking Routes and Colonies
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38. Viking Explorations and Discoveries
The Viking period stretches from about 790 A.D. to 1100.
During this period Vikings raided nearby land, explored, and established trade routes throughout Britain, Ireland, Southern Europe, Northern Africa, and Asia.
This was the only significant exploration taking place in Europe during this period.

39. Viking Explorations and Discoveries
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Viking Explorations and Discoveries
Sun compass

40. Viking Explorations and Discoveries
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Viking Explorations and Discoveries
Leif Erikson:
1st European to discover North America
Erik the Red: Discovered Greenland

41. The Age of Discovery in Europe 1492–1522
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Search for new Eastern trade routes by sea
Prince Henry the Navigator of Portugal sought trade routes around Africa. Established an institute for sea fairing knowledge in Portugal
Europeans explore North and South America
Christopher Columbus was financed by the Spanish to find new trade routes to Asia.
Englishman John Cabot arrived in northeast North America in 1497.

42. The Age of Discovery in Europe 1492–1522
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Spaniard Ferdinand Magellan circumnavigated the globe.
Was killed on a Pacific Island in 1521
Juan Sebastian del Caño completed the circumnavigation in 1522.
Voyages paved the way for the Spanish to take gold from the Incas and Mayas.
Spain’s maritime dominance ended when England defeated the Spanish Armada in

43. Voyages of Columbus and Magellan
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44. The longitude problem was eventually solved in the mid-18th century
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John Harrison
The longitude problem lines of longitude get narrower towards the poles and makes sea navigation difficult over long distances
The longitude problem was eventually solved in the mid-18th century
To solve the longitude problem, Harrison would have to devise a portable clock which kept time to within three seconds a day – far more accurate than even the best watches of the time.

45. Voyaging for Science Ships HMS Endeavour, Resolution, Adventure
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The English wanted to retain maritime superiority.
Captain James Cook (1728 – 1779) undertook three scientific voyages.
Ships HMS Endeavour, Resolution, Adventure
Mapped many islands in Pacific
Systematically measured ocean characteristics
Marine chronograph (longitude)

46. Cook’s Voyages
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47. Oceanography Continues
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More high-technology tools available today
Sonar
Robotics
Computers
Satellites

48. Nature of Scientific Inquiry
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Natural phenomena governed by physical processes
Physical processes similar today as in the past
Scientists discover these processes and make predictions
Called the scientific method

49. The Scientific Method
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50. Theories and Truth Science never reaches absolute truth.
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Science never reaches absolute truth.
Truth is probable and based on available observations.
New observations yield scientific progress.
In reality, scientists have no formal method.

51. Formation of Earth and the Solar System
Nebular hypothesis – all bodies in the solar system formed from nebula
Nebula = cloud of gases and space dust
Mainly hydrogen and helium
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52. Nebular Hypothesis
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Gravity concentrates material at center of cloud (Sun)
Protoplanets form from smaller concentrations of matter (eddies)

53. Protoearth Larger than Earth today Homogeneous composition
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Larger than Earth today
Homogeneous composition
Bombarded by meteorites
Moon formed from collision with large asteroid

54. Protoearth Radioactive heat Spontaneous disintegration of atoms
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Radioactive heat
Spontaneous disintegration of atoms
Fusion reactions
Heat from contraction (protoplanet shrinks due to gravity)
Protoearth partially melts
Density stratification (layered Earth)

55. Density Stratification
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High density = heavy for its size
Early Earth experienced gravitational separation.
High density materials (Iron and Nickel) settled in core.
Less dense materials formed concentric spheres around core.

57. Earth’s Internal Structure
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Layers defined by
Chemical composition
Physical properties

58. Layers by Chemical Composition
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Crust
Low-density, mainly silicate minerals
Mantle
Mainly iron (Fe) and magnesium (Mg) silicate minerals
Core
High-density, mainly iron (Fe) and nickel (Ni)

59. Layers by Physical Properties
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Lithosphere
Asthenosphere
Mesosphere
Outer core
Inner core

60. Lithosphere Cool, rigid shell Includes crust and upper mantle
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Cool, rigid shell
Includes crust and upper mantle
About 100 km (60 miles) thick

61. Continental vs. Oceanic Crust
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62. Asthenosphere Relatively hot, plastic Flows with high viscosity
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Relatively hot, plastic
Flows with high viscosity
Important for movement of lithospheric plates
Base of lithosphere to about 700 km (430 miles) deep

63. Isostatic Adjustment Vertical movement of Earth’s crust
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Vertical movement of Earth’s crust
Buoyancy of lithosphere on asthenosphere
Less dense continental crust floats higher than denser oceanic crust
Isostatic rebound – rising of crust formerly weighed down by glacier ice

64. Isostatic Adjustment
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65. Origin of Earth’s Atmosphere
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Outgassing – occurred during density stratification
Water vapor
Carbon dioxide
Hydrogen
Other gases
Earth’s early atmosphere different from today

66. Origin of Earth’s Oceans
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Outgassed water vapor fell as rain.
The first permanent oceans formed 4 billion years ago.
Salinity developed from dissolved rock elements.
Early acidic rain dissolved more crustal minerals than today.

67. Development of Earth’s Oceans
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68. Life’s Possible Ocean Origins
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Earth’s earliest known life forms are billion-year-old bacteria fossilized in ocean rocks.
These are the building blocks for life on early Earth.
There is no direct evidence of early Earth’s environment.

69. Oxygen Humans require O2.
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Humans require O2.
Ozone (O3) protects from ultraviolet radiation.
Early Earth had little free oxygen.
The lack of ozone may have helped originate life.

70. Stanley Miller’s Experiment
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Organic molecules formed by ultraviolet light, electrical spark (lightning), and a mixture of water, carbon dioxide, hydrogen, methane, and ammonia

71. Stanley Miller and his Experiment
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72. Evolution and Natural Selection
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Organisms adapt and change through time.
Advantageous traits are naturally selected.
Traits are passed to the next generation.
Organisms adapt to environments.
Organisms can modify environments.

73. Plants and Animals Evolve
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Heterotrophs
Very earliest life
Require external food supply
Autotrophs
Evolved later
Manufacture own food supply

74. First Autotrophs Probably similar to modern anaerobic bacteria
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Probably similar to modern anaerobic bacteria
Survive without oxygen
Chemosynthesis from chemicals at deep hydrothermal vents
Supports idea of life’s origins on deep ocean floor in absence of light

75. Photosynthesis and Respiration
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Complex autotrophs developed chlorophyll.
This allowed the use of the Sun for photosynthesis.
Cellular respiration

76. Photosynthesis and Respiration
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77. Great Oxidation Event 2.45 billion years ago
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2.45 billion years ago
Increased oxygen and ozone eliminated the anaerobe food supply.
Light and oxygen kill anaerobes.
Cyanobacteria adapted and thrived.

78. Changes to Earth’s Atmosphere
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Photosynthetic organisms are responsible for life as we know it today.
Reduce CO2, increase O2 to 21%
High oxygen = biodiversity increase
Low oxygen associated with extinction events

79. Plants and Earth’s Environment
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80. Age of Earth Radiometric age dating
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Radiometric age dating
Spontaneous change/decay
Half-life
Earth is about 4.6 billion years old.

81. Radioactive Decay
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82. Geologic Time Scale
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83. End of CHAPTER 1 Introduction to Planet “Earth”
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End of CHAPTER 1 Introduction to Planet “Earth”