Lecture 22

Question 1

What world event lead to people deciding to map the oceanic floor?

Answer 1

World War II and the fight between the allied ships and Nazi U-Boats.

Question 2

What is most of the surface of the Atlantic Ocean made up of?

Answer 2

Alibnar Plane

Question 3

What is the Mid-Oceanic Reach?

Answer 3

Mountain chain in ocean that paralls the shores of North and South America, and Europe and Africa

Question 4

What was the first ocean that the deep sea drilling project drilled into?

Answer 4

Atlantic Ocean

Question 5

What was discovered about Earth’s Magnetic Field?

Answer 5

Depostion and minerals formed clasts. Act as dipoles and align themselves with the lines of the magnetic field. At a certain depth, however, minerals alignments rotated, Then switched back, then rotated, etc.

Question 6

What are the 2 types of magnetic polarity?

Answer 6

Normal and Reversed

Question 7

What is normal polarity?

Answer 7

Northern magnetic pole is close to northern geographical pole, and same with the south

Question 8

What is reversed polarity?

Answer 8

Rotated 180 degrees. South magentic pole is close to north geographical pole and same with the other.

Question 9

How does polarity shift in the ocean?

Answer 9

Proximity of mid oceanic reach = normal polarity. As you move outwards, it reverses. Then switches.

Question 10

Where does the oceanic crust form?

Answer 10

At the mid-oceanic reach.

Question 11

What is Paleomagnetism?

Answer 11

Distribution of the polarity zones at the sea floor.

Question 12

Where are the youngest sediments in the ocean situated?

Answer 12

Exactly in the proximity of mid oceanic reach

Question 13

Where are the oldest sediments in the ocean situated?

Answer 13

In the proximity of the continental margins.

Question 14

How does an Ocean form (Oceanic formation model)

Answer 14

Evolution of an ocean begins in the zone with the continental crust. Ascending currents of the athenosphere push on the crust and stretches the slab, making it thinner. Depression zones form and continent is filled with freshwater. Lots of volcanic activity. Becomes salty as oceanic water moves in. Ascending currents continue. Volcanic rocks with mantle composition occur in continental zone. Basic magma that forms basalts. New matter at surface crystallizes and oceanic crust forms, Continents move away, mid-oceanic reach forms.

Question 15

What is the East African Rift?

Answer 15

An example of modern rifting. Vast Depression zones. Lots of volcanic activity and earthquakes. Vast accumulation of water. HUGE LAKES.

Question 16

What does it mean that the East African Rift has stratified waters?

Answer 16

Waters that are oxygenated ar the surface and toxic at the bottom. Gases from inner earth reach surface and dissolve..

Question 17

What is the Red Sea?

Answer 17

Sea situated between Africa and Arabian Peninsula. An ocean that is in incipient formation due to the break up of a continent.

Question 18

What are the consequences of the mid-oceanic reach being unstable in the red sea?

Answer 18

Fracture continues moving.

Question 19

What are the 5 stages of rifting in an ocean?

Answer 19

1) Pre-rifting
2) Continental Uplift
3) Continental Rift
4) Early Oceanic Basin Formation
5) Mature Oceanic Basin

Question 20

What is pre-rifting?

Answer 20

When the ocean formation has not yet started

Question 21

What is the continental uplift?

Answer 21

Begins with ascending currents from Asthenosphere. Continent is uplifted, Continental crust gets thin

Question 22

What is a continental rift?

Answer 22

Crust thins and continent begins to split

Question 23

What is the early oceanic basin formation?

Answer 23

Narrow, elongated basin floored with oceanic crust, framed by continents

Question 24

What is the mature oceanic basin?

Answer 24

When an ocean actually forms.

Question 25

Which stage marks the beginning of ocean formation?

Answer 25

Continental uplift

Question 26

Where do we study the consumption of the Atlantic ocean?

Answer 26

In the Pacific Ocean

Question 27

What is the zone of subduction?

Answer 27

When the pacific plate is sunken under the North American and Eurasian plate. Transition is gradual

Question 28

What was discovered in the Aleutian Island Arc?

Answer 28

Volcanoes and Earthquakes. Hypocentres of these aligned to form a plane,

Question 29

What is the Benioff Plane?

Answer 29

Plane of subduction. Exists everywhere around the pacific. Sinks under Eastern Coast of Asia and Australia and Southern North America and South America.

Question 30

What is consumption?

Answer 30

When one slab of oceanic crust is completely subducted under continental plate. Entire fossil records are destroyed. Subduction is responsible for volcanic mountains in surrounding area.

Question 31

What happened when an entire ocean was consumed during the Collision of India and Eurasian plates?

Answer 31

Ocean in between was closed, huge mountain range was formed (Geologically, India is a separate continent)

Question 32

Where did Italy originally come from?

Answer 32

Came from Africa and collided with Europe to form the Alps.

Question 33

What happened when Spain collided with Eurasia?

Answer 33

The Pyrannese formed

Question 34

What happend when Greece collided with Eurasia?

Answer 34

Formed Balkan mountains.

Question 35

Where are Italy, Spain and Greece all from and what does this tell us?

Answer 35

Africa. In the next 25 million years, Africa will collide with Europe.

Question 36

What is the Wilson Cycle?

Answer 36

Cycle of birth, formation, evolution, and close-up of oceaninc basin-defined Paradigm of Plate Tectonics

Question 37

What is the Paradigm of Plate Tectonics?

Answer 37

Formation of ocean and movement of continents. Relates to Theory of Evolution.

Question 38

Why does the Paradigm of Plate Tectonics relate to the Theory of Evolution?

Answer 38

Onset of modern plate tectonics put pressure on life forms. Without it, life would be very simple.