1. Exploring the inner and outer shells of earth
I begin the lecture by showing the preview of the movie “The Core”, this to get them excited – hopefully!

3. WHY DO WE CARE ABOUT THE GEOMORPHOLOGY OF THE OCEAN
FLOOR?
(in the context of Oceanography)

4. Earth's magnetic field I care!
Einstein described geomagnetism as one of the chief unsolved puzzles of physics. Neither Earth's liquid outer core nor its solid, yet superhot, inner core has struck scientists as likely sources of its magnetic field. Heat cooks the magnetism out of magnets, and liquefaction melts it away. Physicists were flummoxed.
From Science News, Vol. 156, No. 20, November 13, 1999

5. Chemical Layers Physical Layers
Earth consists of a series of concentric layers or spheres which differ in chemistry and physical properties.
Chemical
Layers
Review of earth physcial/chemical layers.
Physical
Layers

6. Increasing pressure raises the melting point of a material.
Physical state is determined by the combined effects of pressure and temperature.
Increasing pressure raises the melting point of a material.
Increasing temperature provides additional energy to the atoms and molecules of matter allowing them to move farther apart, eventually causing the material to melt.
Both pressure and temperature increase toward the center of the Earth, but at variable rates.
Role of pressure and temperature

7. How do we learn about the inner
structure of the planet?
Seismic waves

8. Seismology is the study of elastic waves that travel through the earth
Two main wave types:
Compression waves (P- waves): travel by squeezing and expanding medium they travel through. They can travel through both solids and liquids (e.g., sound waves).
Shear waves (S-waves): travel by shearing medium they pass through. S-waves can travel only through solids since particles need to be bonded to each other to propagate wave (similar to a bull whip)

9. Earthquake are an incredible source of seismic waves
Seismic waves travel along there quickest route, generally through, the planetary interior to the seismic stations, changing speed every time material properties change.

10. Reconstructing the internal structure of the planet
Combining information from many seismic waves we can get a detailed internal structure of the earth.
Seismic Velocity and Density
solid
Crust & upper mantle: large increases in seismic velocities and density
solid,
more dense
Mantle: Gradual velocity and density increase
Liquid Iron
Outer core: dramatic density increase and no S-waves
At the end of this transparency there is a link on the 03- Quakes_SolarSystem.ppt file to show how earthquakes occur on different plantets of the solar system. You can show this in a very quick and inofrmative way just to make the point.
Inner core: Jump in density and P-wave velocity, S-waves return
solid Iron
Other planets?

11. Earthquakes produce waves in the ocean
NOAA-GlobalOceanWave.mov

12. Earthquakes produce waves in the ocean
Sea level:
RISE
FALL
Courtesy: K. Satake, unpublished

13. World Seismicity Many large earthquakes occur along subduction zones
( )
Many large earthquakes occur along subduction zones
Most “Great” earthquakes are subduction mega-thrust events

14. Major Research Programs in Geophysics
The is also a powerpoint file on EarthScope. I typically show until transparecny number 4 of the EarthScope powerpoint, where it shows the observational network.

15. The Physiography of the North Atlantic Ocean Floor
continental
margins
deep ocean
basins
midoceanic
ridges
This section begins the “physiography”. Begin by saying that his ia a map of the ocean floor obtained by satellite. Then engage the audience to ask them to identify features.

16. Continental Margin Continental margins
Description of each of the physiographic elements
Continental Margin

17. Continental margins are the submerged edges of the continents and consist of massive wedges of sediment eroded from the land and deposited along the continental edge. The continental margin can be divided into three parts: the Continental shelf, the Continental slope, and the Continental rise.
Description of each of the physiographic elements
Continental Margin

18. Deep Ocean Province is between the continental margins and the midoceanic ridge and includes a variety of features from mountainous to flat plains: Abyssal plains, Abyssal hills, Seamounts, and Deep sea trenches.
Deep Ocean Basin

19. Midoceanic Ridge Province consists of a continuous submarine mountain range that covers about one third of the ocean floor and extends for about 60,000 km around the Earth.
Midocean Ridge

20. Midoceanic Ridge Province consists of a continuous submarine mountain range that covers about one third of the ocean floor and extends for about 60,000 km around the Earth.
Midocean Ridge

21. Midoceanic Ridge Province consists of a continuous submarine mountain range that covers about one third of the ocean floor and extends for about 60,000 km around the Earth.
Midocean Ridge

22. WHY DO LAND AND OCEAN EXIST?
Why do land and ocean exist? Continents and ocean basins differ in composition, elevation and physiographic features.

23. Geologic Differences between Continents and Ocean Basins
2-3
Continents and ocean basins differ in composition, elevation and physiographic features.
Elevation of Earth’s surface displays a bimodal distribution with about 29% above sea level and much of the remainder at a depth of 4 to 5 kilometers below sea level.
Continental crust is mainly composed of granite, a light colored, lower density (2.7 gm/cm3) igneous rock rich in aluminum, silicon and oxygen.
Oceanic crust is composed of basalt, a dark colored, higher density (2.9 gm/cm3) volcanic rock rich in silicon, oxygen and magnesium.

24. OCEANIC CRUST = THIN AND DENSER CONTINENTAL CRUST = THICK AND LITHER
Geologic Differences between Continents and Ocean Basins
OCEANIC CRUST = THIN AND DENSER
CONTINENTAL CRUST = THICK AND LITHER

25. 100 cm3
39 g A
10 cm3
12 g B
Explain concept of buoyancy. Question to the students: what happens when these sheres are released into the water? Do they sink or float? How to determine this?
WATER

26. 100 cm3
39 g A
WATER

27. A=positively buoyant
100 cm3
39 g
B=negatively buoyant
WATER

28. Isostasy refers to the balance of an object “floating” upon a fluid medium. Height of the mass above and below the surface of the medium is controlled by the thickness of the mass and its density (similar to ice floating in water).
The concept of Buoyancy is at the heart of Isostasy principle

29. Oceanic Crust Versus Continental Crust
Continents are thick (30 to 40 km), have low density and rise high above the supporting mantle rocks.
Sea floor is thin (4 to 10 km), has greater density and does not rise as high above the mantle.
Oceanic Crust Versus Continental Crust

30. Three spheres surround the rocky portion of the Earth.
Hydrosphere includes all of the “free” water of the Earth contained in the ocean, lakes, rivers, snow, ice, water vapor and groundwater.
Atmosphere is the gaseous envelope that surrounds the Earth and is mainly a mixture of nitrogen and oxygen.
Biosphere refers to all living and non-living organic matter.

31. End of lecture

32. Exploring the inner and outer shells of earth
NOAA-GlobalOceanWave.mov
NOAA-IndianOceanWave.mov