Deck 10: Origin and Evolution of the Ocean Floor

Question 1

Submarine canyons found on the continental slope and rise have been created .

A)by rivers during the ice age
B)because of a plate plunging into the mantle
C)by faulting
D)none of these

Answer 1

D

Question 2

is (are)not part of an ophiolite complex.

A)Residual, unmelted, crustal lithosphere
B)Intrusive, coarse- grained gabbro
C)Steeply inclined, basaltic dikes
D)Basaltic lavas and pillow lavas

Answer 2

A

Question 3

An echo sounder operates by measuring the time required for a .

A)sound pulse to travel from a ship to the seafloor and back
B)radar beam to travel from a harbor patrol boat to a fuzz- buster on a speeding yacht
C)radar beam to travel from a ship to the seafloor and back
D)light beam to travel from a satellite at a known altitude to the sea bottom and back

Answer 3

A

Question 4

Which of the following is NOT true of deep ocean trenches?

A)They may act as sediment traps.
B)They are geologically very stable.
C)They are sites where plates plunge back into the mantle.
D)They are long and narrow depressions.

Question 5

"Black smokers" are associated with .

A)oceanic ridges
B)hot water
C)metal- rich sulfide deposits
D)all of these

Question 6

are not associated with a mid- ocean ridge.

A)Submarine basaltic lava eruptions
B)Shallower depths than abyssal plains
C)Deep ocean trenches
D)Very thin, ocean floor, sediment layers

Question 7

The gently sloping submerged surface extending from the shoreline toward the ocean is termed the .

A)continental rise
B)continental shelf
C)continental slope
D)submarine canyon

Question 8

Geologically, are actually submerged parts of the continents.

A)continental shelves
B)coastal guyots
C)continental trenches
D)abyssal plains

Question 9

Geologically, what is the best way to explain the thousands of feet of coral limestone beneath most atolls?

A)An eroded volcanic seamount rose thousands of feet after the limestone formed.
B)The eroded volcano slowly sank as sea level remained steady or rose gradually.
C)The volcano never reached the surface, allowing a very thick cap of coral limestones to accumulate.
D)Sea level has fallen thousands of feet since the reef began to grow.

Question 10

Which one of the following is not connected in any way with submarine, hot spring vents?

A)thick turbidites on the continental rise
B)black smokers on a mid- ocean ridge
C)sediment rich in metallic sulfides
D)ecological communities living without photosynthesis

Question 11

A(n)is a low lying, coral reef island perched above a sunken, truncated volcano.

A)fringing reef
B)seamount
C)guyot
D)atoll

Question 12

Young oceanic lithosphere typically experiences what type of subduction and at what angle?

A)Forced Subduction; shallow angle
B)Spontaneous Subduction; shallow angle
C)Spontaneous Subduction; steep angle
D)Forced Subduction: steep angle

Question 13

The lies at the base of the continental slope.

A)continental rise
B)offshore shelf
C)off- slope reef
D)continental rift

Question 14

Oceans cover approximately of Earth's surface area?

A)50%
B)90%
C)70%
D)10%

Question 15

is the oceanward edge of a continental shelf.

A)The base of the continental rise
B)The deepest portion of a deep- ocean trench
C)The top of the continental slope
D)The top of the abyssal plain

Question 16

Water depths and seafloor topography are now routinely determined by _ _.

A)by satellite- linked, laser reflector systems
B)computerized, satellite- mounted, parallel transponder systems
C)ship- mounted echo sounders
D)ship- mounted, optical- fiber satellite uplink systems

Question 17

Where in the oceans are biological communities thriving without sunlight?

A)in shallow water, coral reefs
B)in muds of deep- ocean trenches
C)around fissure vents for flood basalts
D)around seafloor, hot spring vents

Question 18

proposed a hypothesis (that later became a theory)on the creation of atolls.

A)Charles Darwin
B)Charles Lyell
C)Isaac Newton
D)James Hutton

Question 19

In the 1870s, the was involved in the first far- reaching, comprehensive study of Earth's oceans.

A)H.M.S. Challenger
B)H.M.S. Brit
C)H.M.S. Moonbeam
D)H.M.S. Bismarck

Question 20

The continental rise is located .

A)at the top of a mid- ocean ridge
B)at the seaward edge of a deep ocean trench
C)between an abyssal plain and continental slope
D)at the top of the continental slope

Question 21

A(n)is a volcanic mountain, built up from the seafloor, that never reached the sea surface.

Question 22

Submerged, flat- topped volcanoes that rise from the deep ocean floor are called _.

Question 23

Valleys that lead from the continental shelf into deeper waters are known as .

Question 24

Where are most of the current active continental margins located on Earth today? Why? What is the relation of the age of rocks on the ocean floor to the location of these active margins?

Question 25

A(n)is the vast, relatively deep, flat, sediment- covered portion of the deep- ocean basin.

Question 26

correctly formulated a basic theory concerning the formation of atolls in the 1800s.

Question 27

Briefly discuss the formation and structure of oceanic crust. What rock compositions are involved and how do these compositions change as a result of interaction with seawater?

Question 28

A(n)marks the site where old, oceanic lithosphere begins its descent into a subduction zone.

Question 29

A low lying, coral limestone island with a central lagoon is called a(n).

Question 30

Seamounts _ _.

A)are a special type of oceanic trench
B)are volcanoes that form on the ocean floor
C)are submarine canyons found near Australia
D)form only in the Pacific Ocean basin

Question 31

_ continental margins typically exhibit wide, extensive, continental shelves.

Question 32

is characterized by the subduction of old dense lithosphere.

Question 33

List several areas on Earth where continental rifting is occurring today. Eventually, what will happen to these areas as rifting continues? Finally, how is continental rifting similar to seafloor spreading and how is it different?