Visual Dictionary Online


Powered by

ocean floorclick to hear

Part of the Earth’s surface beneath the seas and the oceans; its topography is highly variable.
ocean floor continental margin continental shelf guyot magma seamount trench volcanic island island arc abyssal hill sea level mid-ocean ridge continent submarine canyon continental slope continental rise abyssal plain

continental margin click to hear

Underwater extension of the continent; it comprises the continental shelf, the continental slope and the continental rise.

continental shelf click to hear

Section of the continental margin extending from the coast of the continent to the continental rise; its depth is no more than 660 feet.

guyot click to hear

Ancient volcano whose summit has been cut off by erosion and then submerged.

magma click to hear

Molten rock and gas under very high pressure that can reach extremely high temperatures.

seamount click to hear

Isolated mountain of volcanic origin featuring a pointed summit.

trench click to hear

Extremely deep elongated depression bordering a continent or island arc; it occurs when one tectonic plate moves under another.

volcanic island click to hear

Volcano whose summit rises above sea level.

island arc click to hear

String of volcanic islands formed when two tectonic plates meet.

abyssal hill click to hear

Rounded underwater rise of low elevation.

sea level click to hear

Mean water level observed for a given duration (day, month, year); it is used as a reference to define coastal features and calculate the elevation of topographical elements.

mid-ocean ridge click to hear

Group of underwater mountain chains criss-crossing the oceans; it is formed by an outpouring of magma.

continent click to hear

A collective term for the vast landmasses and their submerged margins.

submarine canyon click to hear

Deep valley that is frequently the extension of a river; it ends in a sediment buildup.

continental slope click to hear

Slope of a few degrees that extends from the continental shelf; it is 660 to 6,600 feet deep.

continental rise click to hear

Gently sloping section of the continental margin; it connects the continental slope to the abyssal plain.

abyssal plain click to hear

Zone located at a depth of 6,600 to 20,000 feet; it covers most of the ocean floor.