1. Introduction to Oceanography

2. Layers of the Earth

3. Layers Crust Mantle Core Asthenosphere Mesosphere Outer Core
Inner Core

4. Crust
2 types
1. Continental km thick
2. Oceanic- 8 km thick

5. Lithosphere
Crust and Upper Mantle
Made of 7 major plates
Solid

6. Asthenosphere Semi solid (Plastic) Magma is formed here
Magma Convection currents
Lithosphere (plates) move on top of asthenosphere

7. Mesosphere
Solid because of high temperature and pressure

8. Outer Core Nickel and Iron Liquid Spins around inner core
Causes the Earth’s Magnetic Field
Very dense

9. Inner Core Nickel and Iron Solid
Extreme high temperatures and pressure- compacts molecules=solid

10. Plate Movement- Past, Present and Future

11. Plate Tectonics
The Theory of Plate Tectonics
Plate Boundaries
Spreading Centers(Divergent)
Subduction Zones(Convergent)
Sliding Faults (Transform)
Plate Movement

12. The Theory of Plate Tectonics
“Continental Drift” - theory* proposed by
Alfred Wagner, a German meteorologist (1915)
Explained by:
geologic fit
fossils
* Not accepted by scientific community
- no mechanism to explain plate movement

13. Plate Tectonics - evidence for theory of continental drift
The Theory of Plate Tectonics (cont’d.)
Plate Tectonics - evidence for theory of continental drift
Found 3 types lithospheres plate boundaries,
ridges (spreading centers) Divergent
trenches (subduction zones) Convergent
transform faults (plates sliding past one another)

14. Constructive Margin Mid-Ocean Ridge
Destructive Margin  Subduction Zones
Constructive Margin Transform

15. Conservative Margins-Transform Faults

16. Driving Mechanisms for Plate Motions
3-3
Constructive margins
Midocean ridges
Destructive margins Subduction zones
Driving Mechanisms for Plate Motions

17. Density differences – cool vs. hot
Plate Boundaries
a) Divergent- Spreading centers - ‘rift zones’
Process:
Convection cells form
Density differences – cool vs. hot
Convection cells cause frictional drag on lithosphere
Lithospheric crust weakens

18. Faulting – break in overlying lithosphere Magma flows upward
Plate Boundaries (cont’d.)
a) Spreading centers - ‘rift zones’ (cont’d.)
Faulting – break in overlying lithosphere
Magma flows upward
New lithospheric crust formed

19. Plates split apart -‘divergent plate’ boundary
Plate Boundaries (cont’d.)
a) Spreading centers - ‘rift zones’ (cont’d.)
Plates split apart -‘divergent plate’ boundary
New crust formed - ‘constructive’ plate boundary
Convection Video

20. Lithospheric Plates collide - ‘convergent’ plate boundary
Plate Boundaries (cont’d.)
b) Convergent- Subduction zones
Lithospheric Plates collide - ‘convergent’ plate boundary
Crust destroyed - ‘destructive’ plate boundary
Forms trenches and mountains

21. 3 types of subduction zones:
Plate Boundaries (cont’d.)
b) Subduction zones (cont’d.)
3 types of subduction zones:
Ocean lithosphere into continental lithosphere – form trenches and
mountain ranges
Ex. a): Cascade Mtn. Range
Ex. b): Andes Mtn. Range

22. Plate Boundaries (cont’d.)
b) Subduction zones (cont’d.)
Ocean lithosphere into ocean lithosphere – forms trenches and island arcs
Ex. A): Aleutian Islands (Alaska)
Ex. B) Isthmus of Panama

23. Plate Boundaries (cont’d.)
b) Subduction zones (cont’d.)
Continental lithosphere into continental lithosphere – form mountain ranges
Ex. A) Himalayas

24. Plates slide past one another
Plate Boundaries (cont’d.)
c) Transform faults
Plates slide past one another
Lithospheric crust neither created nor destroyed - ‘conservative’ plate boundary
Ex. A) San Andreas Fault

25. Plate Boundaries (cont’d.)

26. New crust is created at spreading centers at a rate of approximately
Plate Movement
New crust is created at spreading centers at a rate of approximately
1-10cm per year
Old crust is destroyed at the same rate at subduction zones

27. Magnetic anomalies in ocean crust...look at spreading centers
Plate Movement (cont’d.)
Magnetic anomalies in ocean crust...look at spreading centers
paleomagnetism
every so often Earth’s magnetic field flips (every 300K-500K years)
magnetic signal recorded in crust at spreading center as it’s formed

28. More evidence of plate moving..

29. Plate Boundaries (cont’d.)

30. islands or sea mountains formed over hotspots
Plate Movement (cont’d.)
Hot spots
Hawaiian Islands
islands or sea mountains formed over hotspots
(fixed area where magma comes up)
lithosphere moves over hotspot
volcanic mountain over hotspot and in ‘front’ of hotspot

31. Hot Spots?

32. 3-3
Mantle plumes
deep in the asthenosphere as molten rock which rises and melts through the lithospheric plate forming a large volcanic mass at a “hot spot”.

33. Age of Ocean Crust

35. Geological Periods

36. Geological Periods Precambrian 4.6 B - 570 Ma solidification
Cambrian Ma Gondwana, hard shell anim.
Ordovician Ma separation, coldest
Silurian Ma Laurentia collides with Baltica
Devonian Ma pre-Pangea, equatorial forests
Early Carboniferous 356 Ma
Late Carboniferous 306 Ma western Pangea is complete
Permian Ma deserts, reptiles, major ext.
Triassic Ma Life begins to rediversify,Pangea
Jurassic Ma Dinosaurs, Pangea starts to break
Late Jurassic 152 Ma Pangea rifts apart, Atlantic
Cretaceous 94 Ma New oceans, India
K/T extinction 66 Ma end of dinosaurs
Eocene Ma India collides with Asia
Miocene 14 Ma Modern look
Modern
Future World Ma N. Atlantic widen
Future Ma new subduction
Future Ma new Pangea

37. Precambrian
break-up of the supercontinent, Rodinia, which formed 1100 million years ago.   The Late Precambrian was  an "Ice House" World.
Source:
Cambrian Animals with hard-shells appeared in great numbers for the first time during the Cambrian.  The continents were flooded by shallow seas.  The supercontinent of Gondwana had just formed and was located near the South Pole.

38. Ordovician
The end of the Ordovician was one of the coldest times in Earth history.  Ice covered much of the southern region of Gondwana.
Silurian Coral reefs expand and land plants begin to colonize the barren continents.

39. Devonian
By the Devonian the early Paleozoic oceans were closing, forming a "pre-Pangea".  Freshwater fish were able to migrate from the southern hemisphere continents to North America and Europe.  Forests grew for the first time in the equatorial regions of Artic Canada.
Early Carboniferous During the Early Carboniferous the Paleozoic oceans between Euramerica and Gondwana began to close, forming the Appalachian and Variscan mountains.   An ice cap grew at the South Pole as four-legged vertebrates evolved in the coal swamps near the Equator.

40. Late Carboniferous
By the Late Carboniferous the continents that make up modern North America and Europe had collided with the southern continents of Gondwana to form  the western half of Pangea.  Ice covered much of the southern hemisphere and vast coal swamps formed along the equator.
Permian Vast  deserts covered western Pangea during the Permian as reptiles spread across the face of the supercontinent.

41. Triassic
The supercontinent of Pangea, mostly assembled by the Triassic, allowed land animals to migrate from the South Pole to the North Pole; and warm-water faunas spread across Tethys. The first mammals and dinosaurs appeared;
Jurassic By the Early Jurassic, south-central Asia had assembled.  A wide Tethys ocean separated the northern continents from Gondwana. 
Subduction zone Rocky Mountains

42. Formation of the Rocky Mountains

43. Late Jurassic In the Late Jurassic the Central Atlantic Ocean was a narrow ocean separating Africa from eastern North America. 
Cretaceous
Notice that North America was connected to Europe, and that Australia was still joined to Antarctica.

44. K/T extinction The bull's eye marks the location of impact site of a 10 mile wide comet caused global climate changes that killed the dinosaurs and many other forms of life.  By the Late Cretaceous the oceans had widened, and India approached the southern margin of Asia.
Eocene
million  years ago India began to collide with Asia forming the Tibetan plateau and Himalayas (destroying the last of Tethys ocean).  Australia, which was attached to Antarctica, began to move rapidly northward.

45. Miocene 20 million years ago, Antarctica was covered by ice and the northern continents were cooling rapidly.  The world has taken on a "modern" look, but notice that Florida and parts of Asia were flooded by the sea. Arabia moved away from Africa forming Gulf of Aden and Red Sea;
Last Ice Age
When the Earth is in its "Ice House" climate mode, there is ice at the poles.  The polar ice sheet expands and contacts because of variations in the Earth's orbit (Milankovitch cycles).  The last expansion of the polar ice sheets took place about 18,000 years ago. 

46. Modern World
If we continue present-day plate motions the Atlantic will widen, Africa will collide with Europe closing the Mediterranean, Australia will collide with S.E. Asia, and California will slide northward up the coast to Alaska.

47. Future +100
Earth is ~ 4.6 bill years old – suggested cyclic of 500 mill year pattern of assembling and disassembling the land masses;
Future +250