VOCAB CHAP 3

Question 1

BATHYMETRY

Answer 1

The measurement of ocean depth.

Question 2

FATHOM

Answer 2

A unit of depth in the ocean, commonly used in countries using the English system of units. It is equal to 1.83 meters (6 feet).

Question 3

SOUNDINGS

Answer 3

A measured depth of water beneath a ship.

Question 4

RELIEF

Answer 4

islands, shallow banks, and deep basins

Question 5

ECHO SOUNDING

Answer 5

A device that transmits sound from a ship’s hull to the ocean floor where it is reflected back to receivers. The speed of sound in the water is known, so the depth can be determined from the travel time of the sound signal

Question 6

PRECISION DEPTH RECORDER (PDR)

Answer 6

An early type of sonar device that was developed in the 1950s.

Question 7

MULTIBEAM ECHO SOUNDERS/SIDE-SCAN SONAR

Answer 7

to make detailed bathymetric maps of a small area of the ocean floor (used to map the seabed)

Question 8

CONTINENTAL SHELF

Answer 8

A gently sloping depositional surface extending from the low water line to the depth of a marked increase in slope around the margin of a continent or island.

Question 8

SIDE-SCAN SONAR

Answer 8

A method of mapping the topography of the ocean floor along a strip up to 60 kilometers (37 miles) wide using computers and sonar signals that are directed away from both sides of the survey ship.

Question 9

SEISMIC REFLECTION PROFILE

Answer 9

A profile view of the structure beneath the sea floor produced by the energy generated from explosions or air guns

Question 10

SUBMARINE CANYONS

Answer 10

A steep, V-shaped canyon cut into the continental shelf or slope

Question 11

SHELF BREAK

Answer 11

The depth at which the gentle slope of the continental shelf steepens appreciably. It marks the boundary between the continental shelf and continental rise.

Question 11

CONTINENTAL SLOPE

Answer 11

A relatively steeply sloping surface lying seaward of the continental shelf.

Question 12

CONTINENTAL RISE

Answer 12

A gently sloping depositional surface at the base of the continental slope.

Question 13

TURBIDITE DEPOSITS

Answer 13

A sediment or rock formed from sediment deposited by turbidity currents characterized by both horizontally and vertically graded bedding.

Question 13

TURBIDITY CURRENTS

Answer 13

Currents that move downslope, eroding the continental margin to enlarge submarine canyons. Deep-sea fans are composed of turbidite deposits, which consists of sequences of graded bedding.

Question 14

SUBMARINE FANS/DEEP SEA FANS

Answer 14

A large fan-shaped deposit commonly found on the continental rise seawards of such sediment-laden rivers as the Amazon, Indus, or Ganges-Brahmaputra.

Question 15

ABYSSAL PLAIN

Answer 15

A flat depositional surface extending seaward from the continental rise or oceanic trenches.

Question 16

OCEAN TRENCHES

Answer 16

deep linear scars in the ocean floor, caused by the collision of two plates along convergent plate margins

Question 16

FRACTURE ZONE

Answer 16

An extensive linear zone of unusually irregular topography of the ocean floor, characterized by large seamounts, steep-sided or asymmetrical ridges, troughs, or long, steep slopes. Usually represents ancient, inactive transform fault zones.

Question 17

PACIFIC RING OF FIRE

Answer 17

An extensive zone of volcanic and seismic activity that coincides roughly with the borders of the Pacific Ocean.

Question 18

MID-OCEAN RIDGE

Answer 18

A linear, volcanic mountain range that extends through all the major oceans, rising 1 to 3 kilometers (0.6 to 2 miles) above the deep-ocean basins. Averaging 1500 kilometers (930 miles) in width, rift valleys are common along the central axis. Source of new oceanic crustal material.

Question 19

HYDROTHERMAL VENTS

Answer 19

Ocean water that percolates down through fractures in recently formed ocean floor is heated by underlying magma and surfaces again through these vents. They are usually located near the axis of spreading along the mid-ocean ridge.

Question 20

SEAMOUNTS

Answer 20

An individual volcanic peak extending over 1000 meters (3300 feet) above the surrounding ocean floor