27
The Face of Earth
composed of continental-type crust. Examples include the Campbell Plateau southeast of New Zealand and the Seychelles
Bank northeast of Madagascar.
OCEANIC RIDGES. The most prominent
feature on the ocean floor is the oceanic
or mid-ocean ridge. As shown in
Figure 1.27, the Mid-Atlantic Ridge and
the East Pacific Rise are parts of this
system. This broad elevated feature forms a
continuous belt that winds for more than
70,000 kilometers (43,000 miles) around
the globe in a manner similar to the seam
of a baseball. Rather than consisting of
highly deformed rock, like most mountains
on the continents, the oceanic ridge system
consists of layer upon layer of igneous rock
that has been fractured and uplifted.
Understanding the topographic
features that comprise the face of Earth is
critical to our understanding of the mechanisms that have shaped our planet. What is
the significance of the enormous ridge system that extends through all the world’ s
oceans? What is the connection, if any,
between young, active mountain belts
and deep-ocean trenches? What forces
crumple rocks to produce majestic mountain ranges? These are questions that will
be addressed in some of the coming chapters as we investigate the dynamic
processes that shaped our planet in the
Puerto-Rico
Trench
South Sandwich
Trench
M
i
d
- A t la n ti c
R
i
d
g
e
M
i
d - I n d ia n
R
id
ge
S o u th w e s t In d ia n R i d g
e
S o u t h e
a s t In d ia n R id g e
Greenland
Eurasia
Africa
South
America
A rc tic
M id -O ce an R id g e
Gibbs
Fracture
Zone
D e m e r a r a
A b y s s a l P la in
St. Paul
Fracture
Zone
Atlantic
Ocean
Weddell Abyssal Plain
Red Sea
Rift
Indian
Ocean
Alps
C a l d e d o n ia n B e lt
H imal a y a M o u n ta in s
U ra ls
Antarctica
Arctic Ocean
Seychelles
Bank
Chagos-Laccadive
Ridge
Kerguelen
Ridge
Broken
Ridge
Ninety East
Ridge
Walvis
Ridge
Rio Grande
Rise
North Scotia Ridge
South Scotia
Ridge
Java (Sunda)
Trench
East
African
Rift
Valley
A n
d
e
s
Mou
n
ta
in
s