The Seafloor - The Changing Earth: Exploring Geology and Evolution - page 230

submarine fans. Along active continental margins, sediments
derived from the shelf and slope are trapped in an oceanic
trench, and abyssal plains fail to develop. Accordingly, abys-
sal plains are common in the Atlantic Ocean basin, but rare
in the Pacifi c Ocean basin (Figure 9.10).

fl attest, most featureless areas on Earth ( Figure 9.10). Their

fl atness is a result of sediment deposition covering the rug-
ged topography of the seafl oor (

◗

Figure 9.11).
Abyssal plains are invariably found adjacent to con-
tinental rises, which are composed mostly of overlapping

◗

90° 120° 150° 180° 150° 120° 90° 60° 30° 0° 30° 60°

75° 75°

Jan Mayen
Ridge

60° 60°

45° 45°

Hawaiian-
Emperor
Chain

30° 30°

15° 15°

0°

15° 15°

Walvis
Ridge

30° 30°

45° 45°

n

90° 120° 150° 180° 150° 120° 90° 60° 30° 0° 30° 60°

60°

Oceanic ridge system Abyssal plain Aseismic ridge Rift valley Oceanic trench

◗

Figure 9.10 Deep Seafl oor Fractures Features found on the deep seafl oor include oceanic trenches
(brown), abyssal plains (green), the oceanic ridge system (yellow), rift valleys (red), and some aseismic
ridges (blue). Other features such as seamounts and guyots are shown in Figure 9.14. Source: From
Alyn and Alison Duxbury, An Introduction to the World's Oceans . Copyright 1984 McGraw-Hill.

Layers of sediment Oceanic crust

2800
(5120 m)

3600 fathoms
(6583 m)

16 km

Oceanic crust

◗

Figure 9.11 Rugged Seafl oor Topography Seismic profi le showing rugged seafl oor topography
covered by sediments of the Northern Madeira Abyssal Plain in the Atlantic Ocean. Source: From
Bruce E. Heezen and Charles D. Hollister, The Face of the Deep (New York: Oxford University Press,
1971), Figure 8.38, page 329.