Ch. 2.3

Question 1

continental margins

Answer 1

boundaries between continental and oceanic crust. Shallow and close to shore

Question 2

continental shelf

Answer 2

portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea

Question 3

Submarine Canyons

Answer 3

narrow steep sided valleys that cut into continental slopes and continental rises of the ocean.
Formed by turbidity currents

Question 4

shelf break

Answer 4

steepening of the bottom that marks the seaward limit of the continental shelf which begins the continental slope.

Question 5

continental slope

Answer 5

closest to the exact edge of the continent. Begins at shelf break and descends to deep sea-floor

Question 6

continental rise

Answer 6

closest to the exact edge of the continent. Begins at shelf break and descends to deep sea floor.

Question 7

continental rise

Answer 7

sediment moving down a submarine canyon accumilates at the canyon’s base in a deposit called a deep sea fan.

Question 8

deep ocean basin

Answer 8

deep water area, further from land

Question 9

turbidity currents

Answer 9

a rapid downhill flow of water caused by increased density due to high amounts of sediment
underwater avalanche of sediment

Question 10

mid ocean ridges

Answer 10

shallow waters close to the middle of deep ocean basins

Question 11

Why is the Southern Hemisphere referred to as the water hemisphere?

Answer 11

80% of the Southern Hemisphere is ocean as compared to only 61% of the Northern Hemisphere is earth.

Question 12

Active Margin

Answer 12

zone where tectonic plates either converge with or shear past one another
-subduction and volcanic activity occurs
-think of the cliffs on the coast

Question 13

Passive Margin

Answer 13

transition between oceanic and continental lithosphere that is not an active plate margin
-adjacent to where seafloor spreading occurs
-flat long coasts

Question 14

trenches

Answer 14

formed by subduction of a tectonic plate
- parallel to margin
-located on deep ocean floor

Question 15

Abyssal plains

Answer 15

flat region of ocean floor usually at base of continental rise; slope of less that 1 degree toward mid ocean ridge

Question 16

abyssal hills

Answer 16

small submarine hills

Question 17

seamounts

Answer 17

a submarine mountain

Question 18

guyots

Answer 18

seamount with flat top used to be islands that sunk below the sea cause of island weight

Question 19

central rift valley

Answer 19

center of ridge system divergent boundary with magma rising up through the oceanic crust

Question 20

hydrothermal vents

Answer 20

result of seawater percolating down through fissures in the ocean crust in the vicinity of spreading centers or subduction zones the cold sea water is heated by magma and reemerges to form the vents

Question 21

black smokers

Answer 21

solidified minerals in the water that build up around the vents forming chimney-like structures.

Question 22

mantle plume

Answer 22

stationary channel of magma usually far from any plate boundary that rises towards the surface from deep within the mantle

Question 23

hotspot

Answer 23

area of volcanic activity due to the mantle plume

Question 24

Why are hotspots and mantel plumes considered an intraplate feature

Answer 24

they tend to be far from plate boundaries

Question 25

Which of the Hawaiian Islands is the youngest and which is the oldest??

Answer 25

youngest is the Big Island
oldest is kauai

Question 26

What do coral reefs need to survive?

Answer 26

1. shallow clear water for sunlight
2. warm water 68 F - 90 F
3. a site for attachment since coral are sessile organisms

Question 27

Stages of a coral reef in order

Answer 27

1. fringing reef
2. barrier reef
3. atoll

Question 28

Fringing coral reef

Answer 28

grows at base of islands
ex. Carribean

Question 29

Barrier Reef

Answer 29

Island begins to sink as coral grows. The coral is seperated from the island by a wide channel
Ex. French Polynesia and Australia

Question 30

Atoll

Answer 30

Completely surrounded by coral and island is completely submerged
Ex. Pacific and a few in Indian and Caribbean Oceans

Question 31

Other less important factors for growing coral

Answer 31

PH, salinity, and a turbidity of 0

Question 32

bathymetry

Answer 32

measurement of the ocean depths and the charting of the shape or topography of the ocean floor.

Question 33

fathom

Answer 33

measure of depth, 6 feet

Question 34

sonar

Answer 34

a type of electronic depth sounding equipment/ echo sounding. transmits sound waves to the very bottom of the ocean. From the speed of the sound waves and the time required for the energy pulse to reach the ocean floor and come back up they can calculate the depth.

Question 35

satellites

Answer 35

they measure the ocean floor from space by bouncing microwaves off the ocean surface.

Question 36

submersibles

Answer 36

a small underwater craft used for deep sea research. They collect data deep down where humans can’t go.

Question 37

What are the two main marine regions?

Answer 37

continental margins and deep ocean basins

Question 38

Which of the two main marine regions contains the most biological activity

Answer 38

continental margins; specifically in the continental shelf.

Question 39

Characteristics of active margins

Answer 39

steep continental slopes, narrow continental shelves, little to absent rises, continental volcanic arcs, coastal mountain ranges, volcanic island arcs mountain building, and trenches; high in seismic activity(earthquakes)

Question 40

Characteristics of passive margins

Answer 40

gentle continental slopes, wide continental shelves, built-up rises(build-up of sediment), not much seismic activity.

Question 41

On the continental margin where are most submarine canyons located?

Answer 41

continental shelf

Question 42

List two ways in which submarine canyons are formed

Answer 42

1. Turbidity currents
2. river systems adjacent to the current

Question 43

Why are abyssal plains so flat?

Answer 43

Over time, a thick layer of sediment builds up by suspension settling.

Question 44

What is the difference between a seamount and a guyot (tablemount)?

Answer 44

Seamounts are underwater pointed-topped volcanic peaks; guyots are seamounts that rose above sea
level to become an island. Then, due to erosion by wind and waves, their peaks have been flattened and they have sunk beneath the surface.

Question 45

What geographical features are associated with nearby ocean trenches?

Answer 45

Volcanic islands arcs, continental volcanic arcs, seamounts

Question 46

What creates a rift valley?

Answer 46

Divergent plates

Question 47

Where are hydrothermal vents found?

Answer 47

commonly around mid-ocean ridges