Continental
margin
0 km
5 km
10 km
B
Mid-ocean ridge
Distance (kilometers)
Continental
margin
A
Deep-ocean
basin
0
1000
2000
3000
4000
5000
A
B
M id - o c e a n
r i d g e
North
America
Africa
Deep-ocean
basin
FIGURE 16.4 Major topographic divisions of the North Atlantic and a profile from
New England to the coast of North Africa.
CHAPTER 16 Origin and Evolution of the Ocean Floor
396
D I D Y O U K N O W ?
The salinity of water in the Dead Sea is
nearly 10 times greater than the salinity
of normal seawater. As a result, the
water is so dense and buoyant that
people and objects easily float.
The University of Hawaii’s research vessel, Kilo
Moana, arriving at Kodiak, Alaska. (Marshalena
Delaney/AP Photo/U.S. Coast Guard)
Provinces
of the Ocean Floor
Oceanographers studying the topography
of the ocean floor identify three major
areas: continental margins, deep-ocean basins,
and oceanic (mid-ocean) ridges. The map in
FIGURE 16.4 outlines these provinces for
the North Atlantic Ocean, and the profile at
the bottom shows the varied topography.
Profiles of this type usually have their
vertical dimension exaggerated many times
(40 times in this case) to make topographic
features more conspicuous. Vertical exaggeration, however, makes slopes appear
much steeper than they actually are.