Oceanography Study Guide

Flashcards covering ocean floor features, currents, salinity, waves, ocean zones, tides, and continental margins.

Abyssal plain

Flattest place on earth, part of the deep ocean floor, covered in thin sediments deposited by turbidity currents.

Continental rise

Deposition of sediments at the base of the continental slope, missing at Active Continental Margins.

Continental shelf

Part of the continent that is covered by water, wide at passive margins and narrow at active margins.

Continental slope

Steeply sloping edge of the continent.

Guyot

Seamount with a flat top, indicating it was once above sea level.

Mid-ocean ridge

Underwater mountain chain where two tectonic plates are pulling apart, creating new crust.

Rift valley

Location of new oceanic crust formation.

Seamount

Underwater mountain of volcanic origin.

Trench

Deep v-shaped valley in the ocean floor caused by subduction at convergent boundaries.

Current

Continuous stream of water in the ocean

Surface current

Shallow currents caused by wind (top 100 m of ocean). They bring warm water from near the equator to the poles and cold water from the poles back to the equator

Upwelling

Vertical movement of cold, dense water caused by surface winds blowing water out of the way

Gyre

Circular loop of surface currents that spin clockwise in the northern hemisphere and counterclockwise in the southern hemisphere

Coriolis Effect

Deflection (turning) or moving objects (such as winds and surface currents) caused by the earth’s rotation

Deep Currents

Thermohaline circulation caused by differences in density (caused by temperature and salinity). Mixes and exchanges water between the oceans

Salinity

Measure of dissolved salts in water. The ocean’s salinity on average is 35 ppt (parts per thousands)

Wind speed

The speed the wind travels.

Fetch

Uninterrupted distance the wind can blow without changing direction.

Duration

The amount of time the wind blows.

Crest

Peak of a wave.

Trough

Lowest part of the wave.

Wavelength

Distance between wave crests or troughs.

Wave height

Distance between the crest and trough of a wave.

Breaker

A wave that is being affected by water depth and rising higher before crashing into the shore/beach.

Tsunami

Long wavelength wave caused by seafloor displacement like an earthquake, landslide, or underwater eruption.

Surface Layer

Mixed layer where sunlight penetrates and waves and wind mixes the layer.

Thermocline

Layer where mixing stops and the temperature rapidly decreases.

Deep Layer

Deep layer of ocean which is very cold and dark because sunlight cannot penetrate.

Tides

The gravitational pull of the sun and moon.

Continental Margin

The transition between continental crust and ocean floor. They can occur either at a plate boundary or far away from a plate boundary. Continental Margins consist of a continental shelf and slope and may include a continental rise at certain locations.

Active margin

Occur on plate boundaries. Active margins often have trenches, narrow continental shelves, no continental rises, and steep continental slopes. Earthquakes and volcanic mountain ranges may occur near active active margins.

Passive Margin

Occur far from plate boundaries. Passive margins often have wide continental shelves, continental rises, and gentle continental slopes.