Oceans
An Overview
How did the oceans form?
• A long time ago (4.5 billion years) there
were no oceans. The Earth was a hot and
dry environment. When the volcanoes
erupted there was a small portion on
moisture that was shot into the sky. Over
millions of years as the Earth began to cool
the moisture from the sky condensed and
fell as rain. This eventually formed the
present day oceans
Ocean water is salty
• Salinity: Is the
measure of dissolved
solids and salts in a
liquid.
• In ocean water there is
35g of solids per
1000g of liquid.
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Some of the solids are
Sodium 30.6%
Chlorine 55%
Magnesium 7.7%
Sulfur 3.7%
Calcium 1.2 %
Temperature Zones
• The temperature of ocean water decreases
as the depth of water increases
• There are three zones of ocean water
• Surface zone
• Thermocline
• Deep Zone
Surface zone
• The surface zone is the warm top layer of
the ocean. It extends to 300 m below sea
level. Sunlight heats the top 100 m of this
zone. Currents mix the heated water with
the water below
Thermocline
• Is a layer of water extending from 300 m
below sea level to about 700 m below sea
level. In this zone temperature drops with
increasing depth faster than it does in the
other two zones.
Deep Zone
• This layer extends from the base of the
thermocline to the bottom of the ocean
floor. The temperature in this zone averages
a chilling 2 degrees Celsius.
The Water Cycle
• Is a cycle that links all of the Earth’s solid,
liquid, and gaseous water together. The
ocean is very important in the process
because nearly all of the Earth’s water
supply is found in the oceans.
Ocean and heat absorption
• The ocean absorbs a lot of the heat given off
by the sun. It absorbs it at a very slow rate.
If this did not occur the average temperature
on Earth would fluctuate by 100 degrees
Celsius.
Ocean Floor
• The ocean floor is divided into two areas.
• 1) continental margin: made of continental
crust
• 2) Deep Ocean Basin: made of oceanic crust
• If you were to think of the ocean as a
swimming pool the shallow part would be
the continental margin and the deep end
would be the oceanic basin
Ocean floor terms
• Continental shelf: Begins at the shore line
and slopes gently toward the open ocean. It
continues until the ocean floor begins to
slope more steeply downward. The depth of
the continental shelf can reach 200m
Continental Slope
• Begins at the edge of the continental shelf
and continues down to the flattest part of
the ocean floor. Depth ranges from 200m to
4000m
Continental rise
• Base of the continental slope, is made of
large piles of sediment. The boundary
between the continental margin and the
deep ocean basin lies underneath the
continental rise.
Abyssal Plain
• Is the broad flat portion of deep ocean
basin. It is covered by mud and small
organisms. The average depth of this
section is 4000m.
Mid Ocean Ridge
• Are mountain chains where tectonic plates
pull apart. The pulling motion creates
cracks in the ocean floor called rift zones.
As plates pull apart magma rises to fill the
empty space. Heat from either side causes
the crust to expand, forming ridges.
Rift valley
• As mountains build up a rift valley forms
between them in a rift zone
Ocean Trenches
• Are seemingly bottomless cracks in the
deep ocean basin. Ocean trenches form
where one tectonic plate is forced
underneath a continental plate or another
oceanic plate
Seamounts
• Are individual mountains of volcanic
material. They form where magma pushes
it’s way through the tectonic plates, If
seamount builds up past sea level it
becomes a volcanic island (Hawaii)
How do scientists find out the
depth of the ocean floor?
• By ship a scientist will travel across the
entire ocean. During this mission repeated
sonar signals are sent down to the ocean
floor, then they will bounce back up. A
computer record how long it takes each
sonar signal to go to the bottom and back
and from this a depth is calculated.
HW
• Q 1-4 pg. 341
Life in the Ocean
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There are three main groups of marine life:
1) Plankton
2) Nekton
3) Benthos
** These groups are differentiated
according to how they move as well as
where they live**
The Benthic Environment
• The benethic environment refers to the
ocean floor and all of the organisms that
live on it.
• The deepest zone in the benethic zone is the
Hadal zone
The Palagic Environment
• Is the entire volume of water in the ocean
and the marine organisms that live above
the ocean floor.
• Two major zones
• 1) Netric Zone
• 2) Oceanic Zone
Resources from the ocean
• Fishing is a multi million dollar industry
• 75 million tons of fish are harvested each
year from the ocean
• With improved technology such as sonar
and drift nets fisherman can catch a much
greater amount of fish
• Today the fishing industry realizes not to
catch dolphin and other animals so they are
taking precautions!!
Fish Farming
• Many types of fish are being caught in
nature and then are bred many times to
produce fish farms. The benefit of this for
the fishing industry is that there is no
limitation to the amount of harvest or
fishing regulations to deal with.
Seaweed
• Seaweed and algae are being harvested
more than others
• Seaweed is being used a thickeners in food
such as jellies and star bucks coffees. Sushi
is also growing in popularity. Seaweed
consumption is a very large area of growing
American consumption
• Ice cream has seaweed as well!!
Tidal Energy
• Since the ocean is constant in it’s movement
it can be used as a source of energy.
• Wave energy is a clean renewable resource
as well. Recently computer programs have
been used to determine how much energy a
wave carries.
Assignment
• I have listed a few ways that the ocean can
be used for it’s resources. Think of 3
additional ways that the ocean can be used
as a resource or to accumulate income for a
business.