1. Concepts of Oceanography Chapter 1 Earth’s Structure © 2014 Pearson Education, Inc.

2. © 20## Pearson Education, Inc. Concepts for Oceanography Chapter 1 Part C Describe the Earth’s internal structure based on chemical composition. Describe the Earth’s internal structure based on physical properties. Explain how the Earth’s atmosphere and oceans were formed.

3. © 20## Pearson Education, Inc. Concepts for Oceanography Chapter 1 Part C Discuss why life is thought to have originated in the oceans. Describe how the age of the Earth has been determined.

4. © 20## Pearson Education, Inc. Internal Structure of the Earth is the result of density stratification Density is a physical property of matter and is the mass per unit volume. Structure of the Earth

5. © 2014 Pearson Education, Inc. Density Stratification Early Earth experienced gravitational separation that resulted in layers forming in the Earth due to differences in density. –High-density materials (iron and nickel) settled in core. –Less dense materials formed concentric spheres around core.

6. © 2014 Pearson Education, Inc. Earth’s Internal Structure Layers defined by Chemical composition Physical properties

7. © 2014 Pearson Education, Inc. Layers by Chemical Composition Crust –Low-density, mainly silicate minerals Mantle –Mainly iron (Fe) and magnesium (Mg) silicate minerals Core –High-density, mainly iron (Fe) and nickel (Ni)

8. © 2014 Pearson Education, Inc. Layers by Physical Properties Lithosphere Asthenosphere Mesosphere Outer core Inner core

9. © 2014 Pearson Education, Inc. Lithosphere Cool, rigid shell Includes crust and upper mantle About 100 km (60 miles) thick

10. © 2014 Pearson Education, Inc. Continental vs. Oceanic Crust

11. © 2014 Pearson Education, Inc. Asthenosphere Relatively hot, plastic Flows with high viscosity –Important for movement of lithospheric plates Base of lithosphere to about 700 km (430 miles) deep

12. © 2014 Pearson Education, Inc. Isostatic Adjustment 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

13. © 2014 Pearson Education, Inc. Isostatic Adjustment

14. © 2014 Pearson Education, Inc. Origin of Earth’s Atmosphere Outgassing – occurred during density stratification –Water vapor –Carbon dioxide –Hydrogen –Other gases Earth’s early atmosphere different from today

15. © 2014 Pearson Education, Inc. Origin of Earth’s Oceans 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.

16. © 2014 Pearson Education, Inc. Development of Earth’s Oceans

17. © 2014 Pearson Education, Inc. Life’s Possible Ocean Origins Earth’s earliest known life forms are 3.5-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.

18. © 2014 Pearson Education, Inc. Oxygen Humans require O 2. Ozone (O 3 ) protects from ultraviolet radiation. Early Earth had little free oxygen. The lack of ozone may have helped originate life.

19. © 2014 Pearson Education, Inc. Stanley Miller’s Experiment Organic molecules formed by ultraviolet light, electrical spark (lightning), and a mixture of water, carbon dioxide, hydrogen, methane, and ammonia

20. © 2014 Pearson Education, Inc. Evolution and Natural Selection 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.

21. © 2014 Pearson Education, Inc. Plants and Animals Evolve Heterotrophs –Very earliest life –Require external food supply –Food was nonliving organic matter that was abundant Autotrophs –Evolved later –Manufacture own food supply

22. © 2014 Pearson Education, Inc. First Autotrophs 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

23. © 2014 Pearson Education, Inc. Photosynthesis and Respiration Complex autotrophs developed chlorophyll. Chlorophyll allowed the autotrophs to use the Sun for photosynthesis. Photosynthesis uses the suns energy to combine water and carbon dioxide together to make sugar (organic material) and oxygen.

24. © 2014 Pearson Education, Inc. Photosynthesis and Respiration Cellular respiration allows an organism to use the sugar made in photosynthesis along with oxygen to produce energy that can be used for all of the organisms life processes.

25. © 2014 Pearson Education, Inc. Photosynthesis and Respiration Photosynthesis and Respiration are complementary processes. The products of photosynthesis are used in respiration and the products of respiration are used in photosynthesis. Autotrophs and Heterotrophs need each other to survive.

26. © 2014 Pearson Education, Inc. Great Oxidation Event 2.45 billion years ago Increased oxygen and ozone eliminated the anaerobe food supply. Light and oxygen kill anaerobes. Cyanobacteria adapted and thrived.

27. © 2014 Pearson Education, Inc. Changes to Earth’s Atmosphere Photosynthetic organisms are responsible for life as we know it today. Reduce CO 2, increase O 2 to 21% High oxygen = biodiversity increase Low oxygen associated with extinction events

28. © 2014 Pearson Education, Inc. Plants and Earth’s Environment

29. © 2014 Pearson Education, Inc. Age of Earth Radiometric age dating –Spontaneous change/decay –Half-life:time for one-half of the atoms in a sample to decay to other atoms. Earth is about 4.6 billion years old.

30. © 2014 Pearson Education, Inc. Radioactive Decay One half-life of Uranium 235 is when half of the radioactive atoms of Uranium 235 decay into lead 207. Counting the number of each type of atom in a rock sample allows the age of the rock to be determined.

31. © 2014 Pearson Education, Inc. Geologic Time Scale