1. Geology 12
Presents

2. Unit Outline Chp 10 Earth’s Interior Chp 11 Sea Floor
Chp 12 Plate Tectonics
Chp 9 Seismic (EQ)
Chp 13 Structure

3. Chp 11 Seafloor Volcanoes outgasses water to fill oceans
Average depth = 4 km
Continental Margins mark edge of continent from deep sea floor
2 types of margins

5. 1. Passive Margin = where oceanic plate is fused to continental plate and large amount of sediment is deposited.
Ex: Eastern N. America
Cont’l Margin
Cont’l Plate
Oceanic Plate
Cont’l Shelf
Cont’l Slope
Cont’l Rise
Abyssal Plain
Submarine canyon
fused

6. Cut into cont’l shelf-slope by:
Submarine canyons
Cut into cont’l shelf-slope by:
a) rivers when sea-level was up to 130 m lower during ice ages
animation
b) turbidity currents = underwater landslides that erode slope and travel for 100’s of km
Sediments are deposited as a deep sea fan as graded bedding

7. Passive Margins

12. Hudson River Submarine Canyon
New York
Cont’ shelf
Hudson River Submarine Canyon
Cont’ slope

16. 2. Active Margin = where oceanic plate is subducting under continental plate
Ex: W. coast of S. America
Volcano
Cont’l shelf
Cont’l slope
Trench
Abyssal plain
Cont’l plate
Oceanic plate

17. Active Margins

20. Oceanic (spreading) Ridge: where new oceanic plate is being created by volcanism
Island/seamount
seamounts
Rift valley
Pillow lava
Sheeted dikes and gabbro
peridotite
mantle

21. Ocean Ridge

26. Guyots
New volcanic island
Eroded flat by waves
Guyot

27. Guyots & Seamounts

28. Guyots & Seamounts

30. Reefs
Top view
lagoon
Fringing reef
Cross section
Barrier reef
Atoll

31. Fringing Reef Island

34. Barrier Reef Island

38. Atoll

42. Islands get smaller as they age due to:
a) wave erosion
b) oceanic plate sinks as it moves way from divergent boundary or hot spot
See Q14d, p.9 of WS 12.2

44. Use the diagram of a typical ocean basin to answer question 6.
6. The diagram represents a cross-section of an ocean basin. The number which represents a diverging plate boundary is
A. 1
B. 2
C. 3
D. 4

45. Read Chapter 11 Do WS 11.1 Read Chapter 12
Go to Chp 12 Plate Tectonics