oceans exam 2
Card Set Information
oceans exam 2
-avg salinity 3.5 % or 35%
-most salt in seawater is sodium chloride
-it is made up of sodium chloride, metals, other slats, dissolved gases. 3.5 dissolved mineral substances
layer of rapid temperature change
-absent at high latitudes
- depth at which the rate of decrease temperture with increase of depth is the largest.
a layer, gradient of changing density. A thin layer of ocean water witha density that increases rapidly with depth.
layer of rapid salinity change
-corresponds to thermocline
how is salinity measured?
parts per thousand
avg 3.5 or 35 percent.
What add to salinity
-cheminal weathering of rocks on continents
what takes salinity away?
-plants and animals build hard parts
Active continental margins
-ocean lithosphere subducted beneath continent
- associated with deep ocean trenches
-experience volcanic eruptions and earthquakes
Passive continental margins
-not associated with plate boundaries
-experience little volcanism and few earthquakes
- carries the debris ithat is eroded from continents to where it drains.
deep ocean basins
- 30% of earth's surface
- features abyssmal plain, deep sea trenches, seamounts, oceanic plateaus
(deep ocean basin) Abyssal plains
flat, deep ocean floor. it is almost featureless because a thick layer of sediment covers the hills and valleys of the ocean floor below it.
-thick accumulations of sediment
(deep ocean basin) Seamounts
-broad volcanic peaks, isolated volcanic peaks
-many form near oceanic ridges
(deep ocean basin) oceanic plateaus
- similar to continental flood basalt provinces
Mid oceanic ridge
-longest topographic feature on Earth
-divergent plate boundary
new crust created.
-they are broken segments, seprated by transform faults
(coastal environment) Coast
area behind the beach
(coastal environment) beach
dunes or berms
high and low tidal reaches
(coastal environment) Near shore
-beach deposition of sediments
(coastal environment) Offshore
-little to no beach sediments
cause for Tides
earth, sun, moon gravitational interactions
extreme high and low tides
moderate high and low tides
-cause by frictional dragging of a orbital motion along shore floor
-at sea the waves do not reach the bottom, by the coast it does.
(waves) Orbital motion
-it is broken down in coastal areas
(waves) wave refraction
-water waves can be refracted or bent.
(wave refraction) uneven coast
-bays or coves cover them
-waves refract and weaken by the time they reach coves
(wave refraction) Even coast
-it smooths out the coast line
- if left alone, will usually result in no net loss or gain of beach sediment
current drives the longshore drift of beach sediments
-happens in an even coast.
erosion on sea cliffs
these may collapse
-wave erosion is focused at the base of the cliffs
(beach erosion) formations
barrier beach and barrier island