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Where is Andros??. Mercator Projection World Ocean.

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Presentation on theme: "Where is Andros??. Mercator Projection World Ocean."— Presentation transcript:

1 Where is Andros??

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4 Mercator Projection

5 World Ocean

6 What is the inner core made of? Why? Why? Because it is very dense and pulled to center by gravity Iron

7 What is the upper mantle ? Solid or Liquid?

8 Which is the highest density? Ocean crust Ocean crust Or Or Continental Crust Continental Crust

9 Process is called Plate Tectonics Proposed by Proposed by –Alfred Wagner –1880-1930 Less dense (lighter) continental plates float on heavier oceanic plates Less dense (lighter) continental plates float on heavier oceanic plates

10 What is the energy source that moves the plates??? Convection Currents- heated material expands (becomes less dense) and is forced up by heavier (more dense) material. Convection Currents- heated material expands (becomes less dense) and is forced up by heavier (more dense) material. Blanket Effect – Super continent, Pangea, insulated hot interior, causing heat build up and convection currents. Plates are drug along by this movement

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14 Convection currents moving plates and forming new land at oceanic ridges

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16 Cindy Ebinger –plate tectonics Studies rift zones.. Has done most of her work in Ethiopia, East Africa Studies rift zones.. Has done most of her work in Ethiopia, East Africa

17 Rift photo by Ebinger in Ethiopia

18 Plates move apart 8-12 cm/year Fingernails grow 6 cm/year

19 Rift in Iceland

20 Youngest rock at the center – oldest rock farthest from the center (rift valleys)

21 Facts that support continental drift 1. Similar shaped continents 1. Similar shaped continents

22 2. Similar fossils across Atlantic

23 3. Magnetic Reversals

24 4.Sediment deepest at edges of continents – thinnest at ridge (dust settling on ocean surface)

25 5.Youngest rocks are at the center and rocks at the edges of the Atlantic are 150 million years old

26 Active Margin Plates running into each other Plates running into each other Volcanoes, mountain building, earthquakes Volcanoes, mountain building, earthquakes

27 Subduction –one plate moves under the other Volcano 100 km from trench

28 South America is moving west colliding with Nazca plate Trench Mountains

29 Passive Margin Growing plates Growing plates

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31 Volcanic Islands are found only at ACTIVE plate boundaries Forms LITHOGENIC SEDIMENT- break up of rocks (Quartz) Forms LITHOGENIC SEDIMENT- break up of rocks (Quartz) Andros no Quartz –no volcano Andros no Quartz –no volcano –Biogenic sediment Made of skeletons and shells of marine organisms Made of skeletons and shells of marine organisms

32 Why study plate tectonics? What do you find at active boundaries? What do you find at active boundaries? Minerals – Iron – Oil – Gold - Diamonds Present active boundaries are easy to find, finding active boundaries pre- dating Pangea requires a lot of study

33 Active Plate Margin vs Passive Plate Margin Active Margin - little or no shelf (shelf is crushed by movement) Active Margin - little or no shelf (shelf is crushed by movement) therefore minimal amount of fishing (no shallow water for plants), EXEPT at upwellings therefore minimal amount of fishing (no shallow water for plants), EXEPT at upwellings Passive plate margin - very wide shelf Passive plate margin - very wide shelf Therefore (shallow water for plants) major fishing, because of shallow water Therefore (shallow water for plants) major fishing, because of shallow water

34 Shelf is only 8% of the oceans surface, but the most valuable. Average width 40 miles Average width 40 miles Average depth 197 feet Average depth 197 feet Slope is undetectable to eye (flat because turbidity (Mud) currents from rivers level out the slope Slope is undetectable to eye (flat because turbidity (Mud) currents from rivers level out the slope Biologically riches part of the ocean Biologically riches part of the ocean

35 Divisions of oceans Benthic – Benthic – –Topography of the ocean bottom Pelagic – Pelagic – –Water environment

36 Pelagic divisions Photic – Photic – –Lighted areas where photosynthesis takes place Aphotic – Aphotic – –Light does NOT penetrate

37 Pelagic (water) environment divided by depth Neritic – water near the shore Neritic – water near the shore Oceanic water beyond the shelf Oceanic water beyond the shelf Deep Ocean – ocean floor Deep Ocean – ocean floor

38 Neritic (near shore) Large variety of conditions Large variety of conditions Salinity changes caused by: Evaporation Dilution from freshwater rivers Temperature changes- water depth MOST BIOLOGICALLY PRODUCTIVE PART OF THE SEA MOST BIOLOGICALLY PRODUCTIVE PART OF THE SEA

39 Oceanic (beyond the shelf) Conditions are more constant Conditions are more constant –Slow moving currents –Temperature constant (except in thermoclines)

40 Deep Ocean Bathyal – edge of shelf Bathyal – edge of shelf Abyssal – deep ocean Abyssal – deep ocean Hadal – trenches Hadal – trenches

41 Environment of Deep Ocean High water pressure?? High water pressure?? Food ?? No light – no plants ?? Oxygen ?? Oxygen ?? No light – no plants ?? No light – no plants ?? O 2 is brought down by cold water density currents –Organisms are primarily H 2 O, because water is not compressible like air Most of food falls from the surface

42 Sea level has risen twice in the last 30,000 years. Why has sea level changed???? Why has sea level changed???? Glaciers change sea level

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