CH10 Flashcards Preview

ESC1000L > CH10 > Flashcards

Flashcards in CH10 Deck (22):

Ocean Basins

form where two tectonic plates diverge from one another


Mid-ocean Ridge

A ridge defines the axis of spreading
-Accumulation of basalt is newly formed oceanic crust


Extent of Ocean Basins

Oceans and major bodies of water cover 71 % of Earth’s surface


Ocean Bathymetry

mapping the ocean floor using sonar
Sonar waves travel at ~1500 m/sec

Sonar wave is deployed, bounces off ocean floor, and then received by detector

The time interval is used to calculate ocean depth at that point.


Typical Topographical Features of Ocean Basin

Continental Shelf: flooded extension of the continent, are gently sloping submerged surface that extend from the shoreline toward the ocean basin.
Continental Slope: a relatively steep zone(compared with the continental shelf), marking the boundary of continental crust and oceanic crust.
Turbidity Currents:Downslope movements of dense , sediment-­‐laden water.
Continental Rise: consists of a thick accumulation of sediment, much of it deposits from turbidity currents; the continental slope merges into the continental rise.
Abyssal Plain: ocean basin floor.


features of ocean basin cont

Seamounts: topographic peaks on the seafloor, commonly are remnants of extinct volcanic activity


Mid-Ocean ridges

an elevated feature located near the centre of most ocean basins, characterised by extensive faulting and volcanic structures.



generated by surface winds, and transfer energy from one place in the ocean to another


Waves are refracted (bent) as they approach shoreline

occurs when part of the wave reaches shallow water first and slows down, while the deeper water portion of the waves maintains a greater velocity.


Beach drift

occurs when an uprush of water rich to the shoreline at an angle causes sediment to move in a zigzag pattern along the beach


Longshore current

occurs when turbulent water in the surf zone moves in a zigzag motion


Submergent Coast

US Atlanac coast and Gulf
Caused by rising sea level or subsiding land.
Tend to have irregular shape, because
the rising sea floods the low reaches of river valleys, producing bays called estuaries.


Emergent Coast

US Pacific coast
Result from rising land or falling sea level.
Tend to have wave cut cliffs and


Salinity and Density Currents

Currents are flows of water and energy caused by wind, water density(controlled by temperature, salinity


Wave density how is it effected

When the temperature is high, so is evaporation. Consequently the water density increases
When there is heavy precipitation or high runoff(fresh water), seawater will be diluted (salinity decreases), becoming less dense.


Coriolis Effec

influences surface currents; deflects moving water to the right northern hemisphere and to the left southern hemisphere


Deep-­‐Water currents

result when water of a greater density sinks under less dense water.


Density determined by

salinity and temperature (greatest effect). Cold seawater with high salinity is densest


Deep water circulation begins

begins in highest latitudes where water is densest. Surface water becomes dense, sinks, and then travels laterally through the ocean basins in sluggish currents


GravitaPonal aQracPon of the Moon cause

the daily rise and fall of sea level caused


Spring Tides

occur when the moon and sun align and create lower, low tides and higher high tides.
(large tidal range)


Neap Tides

occur when the moon is in the 1st or 3rd quarter phase. Produce lower high tides, and higher low tides.
(Small tidal range)