Flashcards in CH10 Deck (22):
form where two tectonic plates diverge from one another
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
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
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.
occurs when an uprush of water rich to the shoreline at an angle causes sediment to move in a zigzag pattern along the beach
occurs when turbulent water in the surf zone moves in a zigzag motion
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.
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.
influences surface currents; deflects moving water to the right northern hemisphere and to the left southern hemisphere
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
occur when the moon and sun align and create lower, low tides and higher high tides.
(large tidal range)