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The Ocean Floor
By María Sanz
The Ocean Floor
Imagine flying around the world. Below is a land
filled with mountains, plains and deep canyons.
Now, picture this area about seven miles under
the ocean.
Under water there are also numerous hills, slopes
and very deep canyons as you can see from the
ocean floor map on the slide before.
The ocean looks very different under the
water.
The Ocean Floor
• The sea bottom is
divided into three
areas:
* The continental
shelf
* The continental
slope
* The ocean floor
The Ocean Floor
The Continental Shelf
 Surrounds all continents
 Relatively shallow when compared to the
other regions of the ocean
 Extends to the continental slope
The Ocean Floor
The Continental Slope
 A steep drop off that leads toward the
deep bottom of the ocean
 Canyons cut through many areas of the
continental slope.
The Ocean Floor
The Ocean Floor
 Much of the deep ocean floor is covered
in basins
 Many mountain ranges spread across the
ocean floor
 There are deep ocean trenches that are
found in areas of volcanic activity
The Ocean Floor
This is a diagram of where the continental shelf,
continental slope and the ocean floor are in relation
to each other and the coast of continents.
The Ocean Floor
What causes the mountain ranges, canyons,
and deep sea trenches on the ocean floor?
The Ocean Floor
Plate Tectonics!!!
This is the movement of Earth's outer
layer which causes mountains to push
higher and oceans to grow wider.
Seafloor Spreading causes the deep ocean
trenches to develop on the ocean floor.
The Ocean Floor
In the following diagram there is evidence of
seafloor spreading by showing the ages of
the ocean floor.
The red colors are the youngest parts of the seafloor, where fresh new
crust is formed as lava seeps up from the deep interior of the Earth
at spreading ridges.
The green colors are the spreading ridges, older crust, that moves
away from the ridge as new crust is formed.
The blue colors are the oldest regions of the seafloor. They are either
next to continents, or are near areas on Earth where seduction is
taking place.
The Ocean Floor
The deepest ocean
trench is the Marianas
Trench in the South
Pacific Ocean, it is
more than 35,000
feet, or almost 6.6
miles deep.
The Ocean Floor
What is going on at the Marianas trench?
The oceanic plate or in this case the fastmoving pacific plate, plunges downward
toward the mantle, while the continental
plate or the Philippine Plate, rides up over
the top. The forces driving the two plates
together are really intense, so the
underlying oceanic plate creates a trench
where it drags the edge of the continental
crust down as it descends underneath.
The Ocean Floor
This is an example diagram of how the two plates
at the Marianas trench are interacting with each
other.
The Ocean Floor
One of the fastest spreading areas of the
ocean is the:
Eastern Pacific Rise
 A mountain range on the floor of the
South Pacific Ocean, roughly paralleling
the western coast of South America.
The Ocean Floor
The main portion of the rise lies generally about 2,000 mi off the
coast, and it lies about 6,000–9,000 ft above the surrounding
seafloor. The East Pacific Rise has a generally smooth and flattish
surface, and it drops sharply away at the sides.
The Ocean Floor
Next students we are going to take a virtual
field trip exploring the East Pacific Rise.
Information about our trip is on the
following website:
Virtual Field Trip