Name____________________________________________________#____ period____
3.4 Features of the Deep-Ocean Basin
A. Abyssal Plain
1. (def) a flat ________________________ surface extending seaward from the continental rise
or oceanic trench (f. 3.6 p. 81)
2. deepest and ________________ regions on Earth
a. located, on ______________, between 4500m (15,000 ft.) and 6000m (20,000ft.)
3. formed by suspension settling as fine particles of sediment slowly __________ to the deep
seafloor
a. suspension settling (def)the process by which fine-grained material that is being
__________________ in the water column slowly ______________________ on the ocean
floor
b. overtime, these deposits __________ seafloor irregularities creating a flat even surface
(fig. 3.11 p. 87)
4. abyssal plain ________________________ is determined by the type of continental margin
a. convergent active continental margins:
1) fewer abyssal plains are found in the Pacific because sediment carried by turbidity
currents ________ ______ ________ ____ not make it to the seafloor
2) instead, much of the sediment ends up in a ____________
b. passive continental margins:
1) abyssal plains are ____________ in the Atlantic and Indian Oceans
2) smaller ocean size means particles settle out where they ______ __________ the
seafloor
3) turbidity currents carry sediment directly down the continental rise and _____________
it on the ocean bottom (f. 3.6 p. 81)
B. Volcanic Peaks
1. volcanic peaks are very ________________ in the Pacific due to widespread volcanic activity
2. volcanic peaks ________ to various elevations from the ocean floor
a. if they __________ the surface, they form volcanic islands
b. if they remain __________ sea level, but rise more than ___km (.6 mile) from the seafloor
they are called seamounts (CH. 2)
c. an ____________ seamount, with a flattened top, is called a tablemount or guyot (f. 2.26 p.
83)
d. an underwater volcanic peak ________ ________ 1000m (.6 mile) tall is called an abyssal
hill or seaknoll
3. abyssal hill (def) a volcanic peak rising less than 1km above the ocean floor; also called a
_________________
a. one of most of the ________________ features on Earth (several hundred thousand have
been identified)
b. they cover a __________ percentage of the deep-ocean basin
c. shape: gently ______________ with an average height of 200m (650 ft.)
d. in the Atlantic and Indian Oceans they are often ____________ under sediment (f. 3.11 p. 87)
e. they are more ______________ in the Pacific because the rate of sediment deposition is
lower due to the __________________ to active margins
1) the abundance of visible abyssal hills in the Pacific creates __________________
regions called abyssal hill provinces
2) abyssal hill province (def) a deep-sea region where sediment rates are so ______ that
abyssal plains do not develop, instead the area is covered with abyssal hills
C. Ocean Trenches and Volcanic Arcs
1. passive continental margins end in a continental rise that merges _________________ into the
deep-ocean abyssal plain
2. convergent active continental margins ______________ into an ocean trench, there is no
continental rise
3. ocean trench (def) deep linear scars in the ocean floor caused by the __________________ of
two plates at a subduction zone
a. the ________________ side of the trench rises as a volcanic arc
b. examples:
1) the islands of Japan (an example of an island arc)
2) the Andes Mountains (an example of a continental arc)
c. the ______________ portions of the ocean are located in trenches (see Table 3.2 page 90)
d. the majority of ocean trenches are found along the ______________ of the Pacific Ocean
D. The Pacific Ring of Fire
1. Pacific Ring of Fire (def) an extensive zone of volcanic and seismic activity that coincides
roughly with the ______________ of the Pacific Ocean (Pacific Rim)
2. exhibits widespread volcanic and seismic activity due to the prevalence of _________________
boundaries along the Pacific Rim
a. contains the majority of Earth’s ____________ volcanoes
b. is the location of the ________________ of Earth’s large earthquakes
3. a tremendous amount of ____________ is shown along the “Ring” where deep-see trenches at
convergent boundaries are associated with tall volcanic arcs
a. example: Peru-Chile Trench/Andes Mountain system (see fig. 3.13 p. 91)
Directions: Draw the indicated
above each label. Your drawing should indicate the appropriate
height and shape of each feature (use the depth measurements on the left as a reference).
sea level _______________________________________________________________________
1000 m (1km) ___
500 m
sea floor
___