Ocean Basin

Question 1

Ocean Bathymetry

Answer 1

Classified by the slope and depth of the sea floor

Question 2

Abyssal Plane

Answer 2

4.5km deep

Question 3

Ocean trenches

Answer 3

6-11km deep

Question 4

MOR

Answer 4

Depth-1.5-2.5km
Hight- 2.5km

Question 5

Two essential mechanisms for ocean basin formation and shaping

Answer 5

• Isostasy
• Sea floor spreading

Question 6

Isostatic balance between oceanic continental crust

Answer 6

Produces a 5km step at the ocean basin edge

Question 7

Sea floor spreading

Answer 7

Lithospheric plate forms at the axial ridge of an MOR of seafloor spreading when the asthenosphere cools. It is continuously replaced by new asthenosphere rising and cooling at the ridge axis ; it then thickens as it moves away and cools

Question 8

Lithosphere towards the MOR axis

Answer 8

Younger, warmer and less dense. Its lower density makes it more elevated

Question 9

Airy isostasy

Answer 9

• Less dense crust sits on dense mantle
  Mountains balance their weight with a deep root of crust pushing down into the mantle
• Taller mountains need thicker roots for stability
• balance creates a slight weakening of gravity over mountains

Question 10

Internal mobility ( the asthenosphere)

Answer 10

Necessary to allow convection to carry away heat generated by the decay of natural radioactivity within the Earth- otherwise mantle would melt

Question 11

As lithosphere separates,,,

Answer 11

The lithospheric plate cools by the conduction of heat to seawater. As it cools, the lithosphere contracts and become high density

Question 12

How can we track Earth’s magnetic field reversals

Answer 12

Ferromagnesium minerals in sea floor spreading

Question 13

Magnetic tape recorder

Answer 13

As basaltic lavas cool, the iron rich minerals align towards the north pole and when they reach Curie temp (300-500C) , they lose their ability to be magnetized and are solidified however still acquire remnant magnetisation