Download Earth`s Oceans

Earth’s Oceans
Some facts…
• Over 70% of the Earth’s surface is Ocean. That’s about
360 million square km.
• Ocean water is different than fresh water; How?
It is salty. The ocean has many dissolved salts in it with
the greatest amount coming from sodium and chlorine.
• When Sodium (Na) and Chlorine (Cl) combine it forms a
salt called halite, which is the common table salt used to
season food.
What’s the big deal about the
ocean being salty?
• When we talk about how salty the ocean is
we use a term called salinity.
• The Ocean water has an average of 3.5%
dissolved salts. From the 3.5%, 30.6% is
sodium, and 55% is chlorine.
We can’t drink saltwater
• This is a main reason we learn about the salinity
of oceans.
• 97% of all water is salt water, and from the
remaining 3% fresh water, only 1% is readily
available.
• Some parts of the ocean, like in the Red Sea,
can have a salinity as high as 4.1%. This is due
to the high evaporation rate.
What other effects does the salinity
have?
• Salt also causes water to freeze at lower
temperatures, and makes the water more dense.
• The more dense the water is, the easier it is for
things to float.
• The temperatures of the water determine the
type of life that can exist in a given region.
What else is in the ocean water
besides salts?
•
Oceans also contain dissolved gasses.
Can you name a gas that is in oceans?
1. Oxygen
2. Carbon dioxide
3. Nitrogen
So where does all the salt come
from?
• The salts come from mainly dissolved
rocks and soils that rivers and runoff water
bring to oceans.
• Volcanic eruptions also have deposited
salts in oceans.
What about the gasses?
• Oxygen comes from the atmosphere, and
from organisms that photosynthesize.
• Note: Photosynthesis is how plants use
the sunlight’s energy for food, and gives
off oxygen in return.
• Carbon dioxide also comes from the
atmosphere, and from organisms when
they respire (breathe).
• Nitrogen comes from the atmosphere.
Is it possible…
• To go all around the world by ship and
never touch land?
• Yes! While we have made imaginary
boundaries for the oceans, they are all
actually connected.
• Can you name all the oceans from the
largest to the smallest? Hint: There are 5.
Located between the Southern Ocean, Asia,
Australia, and the Western Hemisphere
Located between Africa, Europe, the Southern
Ocean, and the Western Hemisphere
Located between Africa, the Southern Ocean,
Asia, and Australia
Located between 60 degrees south latitude and
Antarctica
Located between Europe, Asia, and North
America, mostly north of the Arctic Circle
So, now we know what ocean water is made
of, and where the oceans are…
• What do you know about the ocean floor?
Is it flat?
Is it rocky?
Is it sandy?
Is it deep? How Deep?
Let’s draw a picture.
An ocean floor example
Ocean floor Features
• Ocean Basin- This is the actual
depression in Earth’s surface that holds
the ocean water
Continental Shelf
• The gradual sloping end of a continent that
extends under the ocean
Continental Slope
• The continental slope drops more steeply,
and extends from the outer edge of the
shelf to the ocean floor
Seamount
• These are underwater
mountains/volcanoes that do not break the
surface of the ocean.
Abyssal Plains
• The abyssal plain is some of the
deepest parts of the ocean, and
some of the flattest parts of Earth
Volcanic Islands
• What is the tallest mountain in the world?
If you said Mt. Everest…
• You’re WRONG!!!
• While Everest is the “Highest” (above sea
level), the volcanic mountain island Mauna
Kea is actually taller from base to peak!
• Mt. Everest is 8,848 m (29,028 ft), but
Mauna Kea is 10,203 m (33,476 ft) from
it’s base in the Pacific ocean.
A Volcanic Island
• Is formed by volcanic eruptions. The lava
continues to pile up and harden and the
mountain/island breaks the surface of the
ocean.
Mid ocean Ridge
The Mid Ocean Ridge
• Is between 70,000 and 80,000 km long
• Is a continuous chain of undersea
mountains that runs all around the world
• Is the longest mountain chain on Earth
• Forms new ocean floor as lava erupts
through the Earth’s crust
What causes the Mid Ocean
Ridge?
• Parts of Earth’s crust—which are called
crustal plates—are constantly moving.
• When these plates spread apart, they
allow the hot magma to enter the ocean
floor.
• As it enters the ocean and cools, it
solidifies, and forms new ocean floor.
Trenches
• Trenches are like canyons on the bottom
of the ocean floor. They are some of the
deepest parts of the earth. Some bottoms
of trenches haven’t even been explored
yet.
The Mariana Trench
• This is the deepest trench we know of; it is
over 11km deep.
• It is located in the Pacific Ocean. Most
trenches are in the Pacific Ocean.
• Mt. Everest could easily fit in the Mariana
Trench, and there would still be over
2000m of water over it!
How deep is the ocean?
• The depth of the ocean is extremely
variable.
• The Ocean has an average depth
between 3 and 4 kilometers.
• The deepest point we know of is the
Mariana Trench (about 11km).
How do we know how deep the
ocean is?
• There are several methods that have been used;
can you think of any?
- sounding
- SONAR
- diving
- submersibles
- Remote Underwater Manipulator
- Satellites
- Gravity Mapping
Some picture examples
Did you know we map the ocean
floor?
• Why do we map it?
• So ships know the best travel routes.
• So we can understand the different depth of the ocean
and the different effects it has on life, as well as the
minerals that are available.
• So we can better understand the formation of the Earth,
and all of the valuable resources it has.
The type of map we use is called a
•
•
•
•
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Topographic Map
Topography is the study of the layout of the land.
How is this different than a regular travel map?
Where else would you use a topographic map?
How do they work?
Road map
Topographic map
Ocean Floor Topography
• When we discussed all the different
sections of the ocean floor, we were
discussing the subsurface topography of
the ocean.