1. Chapter 3 Geology, Chemistry, Physical Features of the World’s Oceans

2. World Ocean Primitive earth and formation of the ocean
early earth thought to be composed of silicon compounds, iron, magnesium oxide, and other elements
gradually, the earth heated, causing melting and separation of elements
water vapor locked within minerals worked its way to the surface, where it cooled, condensed, and formed the ocean

3. World Ocean Ocean and the origin of life
atmosphere formed by gases escaping from deep within the planet
free oxygen formed oxides, oxygen did not accumulate until evolution of modern photosynthesis
Stanley Miller’s apparatus demonstrated that simple organic compounds could have been formed under conditions present on primitive earth

4. Figure 3-1 MILLER’S APPARATUS.

5. World Ocean The ocean today 4 major ocean basins:
Pacific
Atlantic
Indian
Arctic
Pacific Ocean - largest
Arctic Ocean - smallest
Seas - smaller than ocean, essentially landlocked
Gulf-smaller cut off by land

6. Figure 3-3 THE WORLD OCEAN.

7. Continental Drift Earth features are constantly changing
New sea floor added, old removed
Causes movement of continents that rest on it

8. Continental Drift Earth made up of 7 layers Inner core
solid, iron- and nickel-rich
Outer core
liquid (same composition)
Less pressure therefore cooler
Mantle
thickest layer with greatest mass, mainly magnesium-iron silicates
Crust
granite
thinnest and coolest, outermost
Lithosphere
crust and upper mantle
Asthenosphere
region of mantle below the crust

9. Figure 3-4 (upper) COMPOSITION OF THE EARTH.

10. Continental Drift
With more accurate maps in the 17th century scientists began to observe that the continents fit together
Fossils
Distribution and placement of mountains
Moving continents
Alfred Wegener
Continents fit together like pieces of jigsaw puzzle
One supercontinent - Pangaea
Laurasia (Europe, Asia, North America)-Northern
Gondwanaland (India, Africa, South America, Australia, Antarctica)-Southern

11. Figure 3-5 THE SUPERCONTINENT PANGEA.

12. Continental Drift Forces that drive continental movement
With advancement in technology
Magma moves by convection currents
midocean ridges form along cracks where magma breaks through the crust
New crust but earth is not growing
At subduction zones, old crust sinks into the mantle where it is recycled
This activity results in seafloor spreading causing continental drift

13. Figure 3-6 FORMATION OF OCEANIC CRUST AND MOUNTAINS.

14. Figure 3-7 SEAFLOOR SPREADING AND CONTINENTAL DRIFT.

15. Continental Drift Evidence for continental drift
Fit of continental boundaries
Distribution of earthquakes
Seafloor temperatures highest near ridges
Age of crust, as determined by samples drilled from the ocean bottom, increases with distance from a ridge

16. Figure 3-8 (upper) EARTHQUAKE ZONES AND TECTONIC PLATES.

17. Figure 3-A MAGNETOMETER DATA.
Bands indicate reversal of magnetic fields

18. Continental Drift Theory of plate tectonics
lithosphere is viewed as a series of rigid plates separated by earthquake belts (trenches, ridges, and faults)
divergent plate boundaries occur at midocean ridges where plates move apart
They move past each other at faults
Transform faults found in sections of the midocean ridges each side formed by a different plates
Forms a line of cliffs with sharp vertical drops called escarpments
lithosphere splits and moves apart at the rift zones
convergent plate boundaries occur at trenches where plates move toward each other

19. Continental Drift Rift (Deep Sea Vent) Communities
depend on specialized environments found at divergence zones of the ocean floor
first discovered by Robert Ballard and J.F. Grassle in 1977, in the Galápagos Rift
primary producers are chemosynthetic bacteria

20. Ocean Bottom Bathygraphic features
Geological features similar to land: mountain ranges; canyons, valleys; great expanses
Divide ocean bottom into two major regions
Continental margins (lies beneath the neritic zone)
Continental shelf
Shallow submerged extension of the continent
Continental slope
Transition between the shelf and ocean floor
Shelf break
Shelf ends and slope begins
Submarine canyons
Formed by turbidity currents, avalanches of sediment and water that erode the slope
Continental rises
More gentle slope after the continental slope

21. Figure 3-11 CONTINENTAL SHELF.

22. Coral reef, volcano, or island Water-deposited sediment
Sediment from beach erosion
Sediments
Continental rock
Continent
Wave-cut terrace
Subsurface rock
Coral reef, volcano, or island
Water-deposited sediment
River
River sediment
Continental rock
Continental rock
Formation of shelf a, b, c, and d
Stepped Art
Fig. 3-12, p. 56

23. Ocean Bottom Floor of the ocean is the ocean basin
Basaltic rock covered by sediment
Abyssal plains and hills
Flat areas with rises up to 1000m
Seamounts
Form from underwater volcanoes, steep rises
Ridges and rises
Volcanic mountains
Trenches

24. Figure 3-13 LANDSCAPE OF THE OCEAN FLOOR.

25. Table 3-2 Depth of Major Ocean Trenches

26. Life on the ocean floor
continental shelves are highly productive because of nutrient runoff and light
life on the abyssal plains is not as abundant because it relies heavily on surface nutrients and chemosynthesis but more abundant than once believed

27. Composition of the Seafloor
Made of loose particles of inorganic and organic material
Sediment classified according to size or origin

28. Composition of the Seafloor
Hydrogenous sediments
formed from seawater through a variety of chemical processes
e.g. carbonates, phosphorites, manganese nodules
Biogenous sediments
formed from remains of living organisms
mostly particles of corals, mollusk shells, shells of calcium carbonate or silicious planktonic organisms (Form ooze)

29. Figure 3-15 BIOGENOUS SEDIMENTS.

30. Composition of the Seafloor
Terrigenous sediments
produced from continental rocks by the actions of wind, water, freezing, thawing
e.g. mud (clay + silt)
Cosmogenous sediments
iron-rich particles from outer space, land in the ocean and sink to the bottom

31. Finding Your Way around the Sea
Must be able to return to previous locations and find their way around
Basic knowledge of navigation techniques

32. Finding Your Way around the Sea
Maps and charts
Made by projecting features with reference lines
3 Types 
Mercator projections
Type of cylindrical
True direction
Bathymetric charts
Based on depths
Physiographic charts
Perspective drawing

33. Figure 3-17 (a) BATHYMETRIC AND PHYSIOGRAPHIC CHARTS.

34. Figure 3-17 (b) BATHYMETRIC AND PHYSIOGRAPHIC CHARTS.

35. Finding Your Way around the Sea
Reference lines
latitude
longitude

36. Finding Your Way around the Sea
Navigating the ocean
Used moon, stars,a nd sun
principles of navigation
a sextant was used to determine latitude based on the angle of the North Star with reference to the horizon
longitude determined using chronometer (measures time)

37. Finding Your Way around the Sea
Navigating the ocean
Global Positioning System (GPS)
utilizes a system of satellites to determine position
GPS measures the time needed to receive a signal from at least 3 satellites, and calculates position