Transcript The Earth`s Oceans - PAMS-Doyle

The Earth’s Oceans
A Dynamic System where many physical
and chemical changes are taking place!
Ocean Bottom
The World’s Oceans
•71% of the surface of the
Earth is ocean
•97% of all the Earth’s
water is found in the oceans
•The Atlantic, Pacific, and
the Indian oceans are the
major oceans
•The Arctic Ocean,
Mediterranean Sea, and the
Caribbean Sea are part of
the Atlantic Ocean
•The Pacific Ocean is the
largest and the deepest
•Followed by the Atlantic
Ocean, the Indian Ocean is
deeper
Mapping the Ocean Floor
•1872 the
Challenger sailed
from England, it
remained at sea for
three and a half
years. It used wire
to measure ocean
depths. The
Challenger collected
animals and water
samples from the
ocean floor. It used
special
thermometers to
record temperatures
on the ocean floor.
•In 1920 the German ship Meteor
used sonar for the first time to
map the seafloor.
•Today the satellite Topex/Poseidon
orbits the Earth using side scan
sonar to map the bottom of the
ocean
Mapping the Ocean
•Mapping the bottom of the ocean can only
be done by indirect methods, such as echo
sounding, radar, sonar, and seismographic
surveys
The Ocean Floor
•Continental margin consist of the
continental shelf, continental slope, and
the continental rise
•Continental shelf is the relatively flat
area along the edge of every continent: it
ranges from almost nothing to 1200
kilometers, the best fishing, large mineral
deposits, and petroleum are found there
•Continental slope is at the edge of
the continental shelf where the sea
floor may plunge steeply 4-5
kilometers
•Marks the boundary between the
continental crust and the oceanic
crust
•Continental rise is the area
between the continental slope and
the ocean floor
•It is made of sediments that wash
down from the continental shelf
•Turbidity current carry large
amounts of these sediments in
masses of moving water, it is like
an underwater avalanche
•Submarine canyons are deep
V shaped valleys cut through
the continental shelf and slope
Features of the Ocean Floor
Abyssal Plain
• Large flat areas on the bottom of
the ocean
• Atlantic and Indian oceans have
largest abyssal plains because
almost all the worlds major rivers
flow into them producing a large
amount of sediment deposits in the
plains
Seamounts and Guyots
• Seamounts are underwater
volcanic mountains
• They have steep sides and narrow
summits and rise more than 1000
meters above the sea floor
• When seamounts rise above the
surface of the ocean they become
islands
• Guyots are seamounts that do not
rise to a peak or have eroded tops
Midocean Ridges
•Largest mountain ranges on the
Earth
•These are formed where the plates
are pulling apart
•Rift valleys run along the middle of
the midocean ridges
Trenches
•The deepest part of the ocean
found along edges of sea floor
•Long narrow crevices that can be
11,000 meters deep
•Deepest trench is the Mariana
Trench in the Pacific Ocean that is
more than 11,000
meters deep
Hydrothermal Vents
•Openings into the mantle of the Earth
where sea water seeps down and
returns to the ocean
Hydrothermal Vents
Reefs
•Reefs are large masses and ridges
of limestone rocks produced by the
shells of animals
•There are three types of coral
reefs: fringing reefs touch the
shoreline of a volcanic island
Coral Reefs (cont)
•Barrier reefs that are separated
from the shore by an area of
shallow water called a lagoon
Coral Reefs (cont)
•And an atoll that is a ring of coral
reef that surrounded an island that
has beenworn away or sunk
This is the easy part!!!!!
The Water Cycle
•The ocean is a source of fresh water for
all living things
Temperature of Ocean Water
•The sun is the major
source of heat for the
ocean
•Surface zone -100-300
meters deep,
temperature fairly
constant, waves and
surface winds mix the
water and transfer the
heat downward
Temperatures (cont)
•Thermocline- found
directly under the
surface zone,
temperature drops
rapidly, less dense
warm water floats
on top of the more
dense cold water
Temperature (cont)
•Deep zone- has
extremely cold
water, extends from
the thermocline to
depths of 4000
meters or more,
temperature
decreases only
slightly
•Temperature below
1500 meters is only
4°
Temperature
•The three ocean zones are not
found in the Arctic or Antarctic
•The surface temperatures are
always very cold
Important Feature! Upwelling
•When the cold currents get near the
coast they force up nutrient rich water
to the surface, this is called upwelling
•Upwelling is important because it
produces rich fishing grounds and
plentiful food for marine life
And you thought the ocean was
just for fun!!!!!!!
Oceanography Two
Temperature Zones, Waves, and Currents
Tides
• These are the regular rise and fall
of ocean water caused by the
gravitational pull between the
moon and the Earth
• A bulge occurs in the ocean nearest
the moon, this is the high tide and
in the opposite is the low tide
• There are two high tides and two
low tides a day
• Spring tides are high tides higher
than other high tides and neap
tides are low tides lower than other
low tides
Moving Ocean Water
•Waves are pulses of energy that move
through the ocean
•They carry energy, not matter
•They begin as wind stirred ripples on
the surface of the water
•The greater the wind, the greater the
wave
Wave Formation
•The height of the wave depends on
wind speed, the length of time the
wind blows, and the distance the wind
blows
•Increasing any of these can increase
the size of the wave
Wave Trivia
•The highest wave every noted
was 34 meters high in 1933
during a wind storm in the
Pacific
Wave Characteristics
•The crest is the highest part of the
wave
•The trough is the lowest part to the
wave
•Wavelength is measured from crest
to crest or trough to trough
Waves (cont)
•Waves are more destructive in the
winter
•Tsunamis is a giant wave caused
by earthquakes
Currents
•Currents can be described as
“rivers” in the ocean
•Two factors cause currents:
wind patterns and water density
differences
Surface Currents
• Currents caused by winds are
surface currents found at a depth
of several hundred meters
• There are warm and cold water
currents, depending on where they
come from
• These are called long-distance
currents
• These currents form a continuous
world wide pattern of water
circulation
Deep Currents
• Deep water currents are caused by
the differences in water density
• Cold water and saltier water is
more dense
• Deep currents usually flow in the
opposite direction of surface
currents
• The densest water in the world is
found in Antarctic, this current
flows northward toward the
equator at the same time warm
current flow toward Antarctic
Deep Currents (cont)
•When the cold currents get near the
coast they force up nutrient rich water
to the surface, this is called upwelling
•Upwelling is important because it
produces rich fishing grounds and
plentiful food for marine life
Properties of Ocean Water
•Ocean water is a
mixture of gases
and solids dissolved
in pure water
•Oceanographers
believe that ocean
water contains all of
the natural
elements found on
Earth
•All but 5 have been
found
Salts in Ocean Water
•Salinity is the
amount of dissolved
salts in ocean water
•Sodium Chloride is
the most common
salt
•Average salinity of
the ocean is 35 o/oo
•Salt comes from
volcanic activity,
erosion of the land,
and wave erosion of
beaches
Sea salts
Parts per
Thousand
chloride
19.3 o/oo
sodium
10.7 o/oo
sulfate
2.7 o/oo
magnesium
1.3 o/oo
calcium
0.4 o/oo
potassium
0.4 o/oo
bicarbonate
0.15 o/oo
bromide
0.07 o/oo
other
0.06 o/oo
Total
Salinity
35.08 o/oo
Salinity
•Salinity can be greater
or less than the
average of 35 o/oo
•Lower salinity where
freshwater rivers enter
the ocean
•Salinity is higher
where there is greater
evaporation and in
polar regions where
only fresh water
freezes
•Animals using certain
salts to build their
shells can lower
salinity
Gases in Ocean Water
•Nitrogen, carbon
dioxide, and oxygen
are the most
abundant gasses
found in ocean
water
•Oxygen and carbon
dioxide are essential
for plant growth
•There is more gas
found at the surface
of the water where
plant growth occurs
Deep Cold Water
•Cold water holds
more gas than warm
water
•When the colder
denser water sinks
to the bottom it
carries oxygen rich
water that aids in
the survival of deep
water species
Ocean Life Zones
•Plant and animal life in the ocean is
affect by three factors: amount of
sunlight, temperature, and pressure
•Plants and animals can be classified
into three major groups according to
their habitats of the water in which
they live
Plankton
•Largest group of animals and plants
that float at or near the surface
•These get the most sunlight
•Found at depths of 1 to 200 meters
deep
•Very small organisms (plankton
that whales eat)
Nekton
•Contains all forms of
organisms that swim around
•They can actively search for
food, prey or predators
•These are found in all areas of
the ocean
Benthos
•Organisms that
live on the ocean
floor
•Benthic plants
live in shallow
water so they can
get the necessary
sunlight
•Oysters, crabs,
starfish are all
benthic
•Some even live in
the deepest parts
of the ocean
Plankton, Nekton, and Benthos
Ocean Environments (Zones)
•The
classification
of the ocean
into life
zones is
based on the
conditions of
the oceanconditions
that vary
widely
Intertidal Zone
•The region that lies between
low and high tide
•Organisms must be able to live
without water some of the time
•They must find someway to
attach so they are not washed
out when tide goes out
•Includes anemones, crabs,
mussels, and plants
Neritic Zone
• Extends from the low tide line to
the edge of the continental shelf
• Depth of about 200 meters
• Receives plenty of sunshine
• Pressure is low and temperature is
constant
• Plankton, nekton, and benthos
plants and animals are found here
• Riches part of the sea: contains
fish, clams, snails, some smaller
whales, and lobsters
• Much of the seafood we eat is
found here!
Open-Ocean Zones
• Bathyal zone begins at the
continental slope and ends about
2000 meters
• Sunlight cannot penetrate to the
bottom
• Squid, octopus, and large whales
are found here
• Abyssal zone extends to over 6000
meters
• No sunlight can penetrate, high
pressure and low temperatures
• Most animals are small and
strange!
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