Exploring the Oceans
71% of the Earth’s Surface is covered with salt
water. Most of this water is found in the global
ocean.
The global ocean is divided by the continents
into five main oceans.
1. Pacific Ocean – the largest ocean, flows
between Asia and the Americas
2. Atlantic Ocean – half the volume of
Pacific Ocean
3. Indian Ocean – third largest
4. Artic Ocean – smallest ocean and mostly
covered with ice
5. Southern Ocean – extends from the coast
of Antarctica to 60 south latitude
How Did the Oceans Form?
While the Earth was cooling, sometime after 4
billion years ago, water vapor began to
condense and fall as rain. The rain filled
deeper levels of the Earth’s surface and our
first oceans began to form.
• Did you know that most of the salt in the
ocean is the same kind of salt sprinkled on
your food. Its called sodium chloride
Why are the Oceans Salty?
Salts are added to the oceans from rivers,
streams and creeks. As they flow toward the
oceans, minerals are dissolved from land.
As ocean water is evaporated, the solids are
left behind.
Salinity – a measure of the amount of
dissolved salts in a given liquid.
Some parts of the oceans are saltier than
others, why?
1. Climate – hotter, drier climates have
increased evaporation leaving behind
more solids.
2. Current – bays, gulfs and seas have less
current. Parts of open ocean that have
no current have an increase in salinity.
Temperature Zones pg 333 of Text
The temperature of the ocean water decreases
as depth increases. Water in the ocean can
be divided into three layers:
1. Surface zone- warm, top layer of ocean
water
2. Thermocline- second layer
3. Deep zone – third layer that extends from
the base of the thermocline to the bottom
of the ocean
The Ocean and the Water Cycle
The water cycle is the continuous movement
of water from the ocean to the atmosphere
to land and back to the ocean.
• Condensation
• Precipitation
• Evaporation
The ocean is an important part of the water
cycle because nearly all of Earth’s water is
in the ocean.
A Global Thermostat
The ocean plays an important role in keeping
the Earth suitable for life by absorbing and
holding energy from sunlight.This process
regulates temperatures in our atmosphere.
The Gulf Stream moves water and the energy
it has absorbed from the equator to northern
coastal areas causing warmer climates.
11.2 – The Ocean Floor pg 340
Continental shelf- gently sloping section
between the shoreline and continental slope
Continental slope- steep inclined section
between continental rise and continental
shelf
Continental rise- gently sloping section
between continental slope and abyssal plain.
Abyssal plain- large, flat, almost level area of
the deep-ocean basin
Mid-ocean ridge- a long, undersea mountain
chain that forms along the ocean floor
Rift valley- long, narrow valley that forms as
tectonic plates separate
Seamount- a submerged mountain on the
ocean floor at least 1,000 m high and has a
volcanic origin
Ocean trench- steep, long depressions in the
ocean floor running parallel to a chain of
volcanic islands or continental divide
11.3 – Life in the Ocean
There are three main groups of marine life:
1. Plankton- organisms that float or drift freely
near the ocean’s surface
Phytoplankton – plant-like
Zooplankton – animal-like
2. Nekton- organisms that swim actively in the open
ocean
3. Benthos- organisms that live on the ocean floor
The Five Benthic Environments
1. Intertidal zone- this is the shallowest
benthic zone and is located between high
tide and low tide limits.
2. Sublittoral zone- begins at low tide limit
and ends at the edge of the continental
shelf
3. Bathyal zone- extends from the edge of the
continental shelf to the abyssal plain
4. Abyssal zone- contains no plants and few
animals. It is the largest zone and is found
on the abyssal plain.
5. Hadal zone- the deepest benthic zone,
found on the floor of the ocean trenches.
The Pelagic Environment
The zone found at the surface and the middle
depths. There are two major zones in this
environment.
1. Nertic zone- covers the continental shelf. This
zone is warm and shallow, containing the
largest concentration of marine life.
2. Oceanic zone- volume of water that covers
the entire ocean except the continental shelf.
Ocean Pollution 11.5
For hundreds of years, humans have been
dumping their trash into the oceans because
the frame of mind was “out of sight-no
more worries”.
Boy were we WRONG
=
Nonpoint-source pollution- pollution that
comes from many sources rather than just
one site
Point-source pollution- pollution that comes
from a specific site