1. Bell Ringer
In which ways do tectonic plates move?

2. MARINE BIOLOGY Essential Question: How do tectonic plates move?
Learning Goals:
Review concept of Pangea and formation of the Earth.
Learn how the tectonic plates move and what structures they form.
Agenda:
Pangea handout
Chapter 2 (part 2) Lecture
Upcoming:
Chapter 1 Quiz (Due Next Class)
Current Event (Due Next Class)

3. The Water Planet (SLIDE CORRECTION)
Our planet is mostly WATER
Land coverage = 30% of the surface!
Water coverage = 70% of the surface!
The oceans are NOT distributed evenly!
Northern Hemisphere is 60% Water vs. 40% Land
Southern Hemisphere = 80% Water vs. 20% Land

5. The Sea Floor
Chapter 2 (Part 2)

6. The Mid-Ocean Ridge System
Technological advancements developed during World War II led to the first detailed survey of the ocean floor & discovery of the Mid- Ocean Ridge System.
The Mid-Ocean Ridge System is largest geological feature on Earth!
Appears as a system of submerged mountains that encircle the continents like the seams of a baseball.

8. Major Features of the Ocean Floor (Cont.)
Ridges: Continuous chain of volcanic submarine mountains.
Location of the youngest crust
Volcanoes are commonly found here.
Trenches: Deep depressions where one crust slides under another.
Site of older oceanic crust
Volcanoes are also commonly seen here
Transform Faults: Cracks in the crust that slide passed each other.
Earthquakes are common here

12. Major Features of the Ocean Floor
Volcanic Islands: Normally formed by exposed top parts of Ridge
Seamount: Submerged mountain
Guyot: Flat topped seamount

15. Magnetic Polarization of the Ocean Crust
The Oceanic Crust is composed of sections that change polarity.
On average every 700,000 years the earth’s poles are REVERSED!
But can occur as often as years or 10 Million + years!
It takes 5,000 years for the process to be COMPLETED!
The measurable change in polarity further proves the crust originates at the ocean ridges.

17. Sea-Floor Spreading and Plate Tectonics
Sea-floor spreading is only part of the story.
The Lithosphere (previously discussed) floats atop the asthenosphere (upper mantle) and is divided into Lithospheric Plates!
They can contain continents.
As the lithospheric plates move, so do the continents on them
The boundaries of the lithosphere correspond to the mid-ocean ridges.

19. Cause of Plate Movement
Geologist originally hypothesized plate movement was caused by convection of the mantle onto the lithosphere.
The newly accepted hypothesis states older oceanic lithosphere cools and sinks into the mantle, forming trenches.
Trench formation pulls on ridge, weakening it, and allows magma to flow through
It is still believed magma flow is aided by convection of the upper mantle

20. Mantle Convection Clip

21. Lithogenous & Biogenous Sediment
Lithogenous Sediment
Fine Rocks
Coarse Rocks
Red Clay (Most Common on the ocean floor)
Biogenous Sediment: Skeletons & Shells
Skeleton and Shells of Marine Organisims
Diatoms
Radiolarans
Foraminiferans
Coccolithophorids
Microfossils

24. Geological Provinces of the Ocean
The sea floor is divided into main regions
Sea Floor
Continental Margin
Previously discussed
The boundaries between continental crust and oceanic ocean.

25. Continental Margin (Continental Shelf)
Most Superficial
Submerged Continental Crust
Biologically richest part of the ocean
Too gradual to see with naked eye
0.6 mi (Pacific Coast of South America) to 470 mi (Artic Coast of Siberia)
The Continental Shelf ends at the Shelf Break where it becomes abruptly steeper.

26. Continental Margin (Continental Slope)
Leads from the Shelf to the Rise
Considered the edge of the continent
Canyons cut across the slope and channel sediments to the sea floor

27. Continental Margin (Continental Rise)
Deepest part of the continental margin
Accumulates sediment channeled by the canyons
Sediment deposits as a “deep sea fan”.
Leads onto the abysmal plane

29. Active vs. Passive Margins
Active Margins
Site of Trenches or Ridges
Volcanoes and Earthquakes occur here
Ex. West Coast of the South America and the Nazca Plate (Trench Created)
Passive Margins
Margins without Trenches or Ridges
Benign areas
Ex. Eastern Coast of South America resting on the South American Plate.

31. MARINE BIOLOGY Essential Question: How do tectonic plates move?
Learning Goals:
Review concept of Pangea and formation of the Earth.
Learn how the tectonic plates move and what structures they form.
Agenda:
Pangea handout
Chapter 2 (part 2) Lecture
Upcoming:
Chapter 1 Quiz (Due Next Class)
Current Event (Due Next Class)