Deformation, Mountain Building, and the Continents - The Changing Earth: Exploring Geology and Evolution - page 266

◗

Figure 10.21 The Andes Mountains in South America

Passive continental margin

Sea level

Continental
lithosphere

Oceanic
lithosphere

Prior to 200 million years ago,
the western margin of South America
was a passive continental margin.

a

Asthenosphere

Sediments

Active continental margin

Sea level

Continental
lithosphere

Oceanic
lithosphere

Orogeny began when this area
became an active continental margin
as the South American plate moved
to the west and collided with oceanic
lithosphere.

b

S e d im e n t s

Asthenosphere

Deformation

Sea level

Continental
lithosphere

Oceanic
lithosphere

D e f o rm a ti o n

Continued deformation,
plutonism, and volcanism.

c

Asthenosphere

View of the Andes in Chile.

d