The continental crust

Question 1

Active volcanism in the andes

Answer 1

• radar mapping shows active deformation of the ground
• 4 large volcanoes show that magma is rising towards the surface
• some magma is a new addition to the continental crust

Question 2

Continent to continent collision: Himalaya

Answer 2

• India was originally on a separate plate until collision with the Eurasian plate starting approx 35 million years ago
• Indian plate currently moving NE at 5cm per year
• eurasian plate moving north at 2cm per year
• compression and shortening of the crust
• the collision has led to extensive deformation of the Asian continent

Question 3

Airy isostasy

Answer 3

columns of similar density but different thickness

compensation depths below the lithosphere

Question 4

Pratt isostasy

Answer 4

columns of different density balanced in proportion to their different thickness
(compensation depths below the lithosphere)

Question 5

Isostasy

Answer 5

• compensation depths below the lithosphere (Pratt and Airy)

- the general lack of gravity anomalies shows that isostatic equilibrium is the usual cade

Question 6

Topography is mainly caused by

Answer 6

• different thickness of continental crust

- age of the oceanic crust

Question 7

Isostatic effects of ice loading

Answer 7

time lag shows:

• viscosity of mantle
• elastic strength of lithosphere