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Chapter 11
Oceans Control the Water
Cycle
11.1: Ocean Basins
How old is the
Earth?
-believed to be about 4.5 billion
years old
How old are
our oceans?
-believe to be more than 3 billion
years old
Where did the
ocean water
come from?
-as the Earth cooled down, water
was released into the
atmosphere from volcanic
material, the water cycles
started and water collected in
ocean basins
Study:
• Figure 11.2 – Volcanoes helped form Earth’s oceans.
11.1: Ocean Basins
What are the
five major
oceans and
what are
their relative
sizes?
-the five major oceans from largest
to smallest are:
1) Pacific
2) Atlantic
3) Indian
4) Southern (includes all
southern portions of the Pacific,
Atlantic and Indian oceans and
completely surround Antarctica)
5) Arctic
Study:
• Figure 11.1 – Earth’s oceans
11.1: Ocean Basins
What are some
features of
the ocean
floor?
-similar features as seen on land
-mountain ranges, valleys, flat
plains, canyons and volcanoes
(usually appear in a much
larger scale than on land)
The ocean
floor has two
distinct parts:
1) Ocean basins
2) Continental Margins
Look at:
• Figure 11.3 – Map of mountains, valleys, and canyons on the ocean floor.
11.1: Ocean Basins
Ocean Basins:
-formed by weathering and erosion
of the ocean floor along with
the movement of Earth’s crust
-large plates moving around on a
layer of molten rock
-can form trenches when plates
collide or ridges where they
spread apart from
-between trenches and mid-ocean
ridges are the abyssal plains
and the occasional seamount
Study:
• Figure 11.4 – Tectonic plates move apart at a mid-ocean ridge.
• Figure 11.5 – When tectonic plates collide…
11.1: Ocean Basins
Continental
Margins:
-regions of the ocean floor that lie
underwater along the edge of
continents
-made up of a continental shelf
and a continental slope
What joins the
flat ocean
basins and
steep
continental
slopes?
-between the basin and slope is a
gentle sloping continental rise;
an area where sediments from
continents build up
Study:
• Figure 11.6 – Features of the ocean floor at the edge of continents.
11.1: Ocean Basins
What is a
turbidity
current?
-when too much sediment builds
up on continental slopes and it
collapses (underwater
landslide)
-spreads sediments out along
ocean floor
What are
submarine
canyons?
-some turbidity currents and large
rivers are strong enough to
carve out large sections of
continental shelf, forming
canyons
Look at:
• Figure 11.7 – Turbidity currents…
• Figure 11.9 – Location of submarine canyons…