Download The Ocean Floor

The Ocean Floor
Studying the Ocean Floor
Scientists
use sonar to
determine the oceans depth
The sound moves through
the water, bounces off the
ocean floor, and returns to
the ship
Ocean Basins
 Ocean
basins are low areas of
Earth that are filled with water
 The
continental shelf is the
gradually sloping end of a
continent that extends under the
ocean to 350 m deep
The Ocean Floor
 Beyond
the shelf, the ocean floor
drops more steeply, forming the
continental slope.
 The
continental slope extends
from the outer edge of the
continental shelf down to the
ocean floor.
Ocean Basins
Beyond
the continental
slope lie the trenches,
valleys, plains, mountains,
and ridges of the ocean
basin
Ocean Basins
 In
the deep ocean, sediment,
derived mostly from land, settles
constantly on the ocean floor.
 These
deposits fill in valleys and
create flat seafloor areas called
abyssal plains.
The Ocean Basins
Some
areas of abyssal
plains have small hills and
seamounts.
Seamounts
are underwater,
inactive volcanic peaks
Ridges and Trenches
 Mid-ocean
ridges can be found
at the bottom of all ocean
basins.
A
mid-ocean ridge is the area
in an ocean basin where new
ocean floor is formed.
Ridges and Trenches
On
the ocean floor,
subduction zones are
marked by deep ocean
trenches.
Trenches and Ridges
A
trench is a long, narrow,
steep-sided depression
where one plate sinks
beneath another.
Question 1
What
shelf ?
is the continental
Answer
The continental shelf is the
gradually sloping end of a
continent that extends under
the ocean.
Question 2
 Which
structure extends from the
outer edge of the continental shelf
to the ocean floor?
A. abyssal plain
B. continental slope
C. oceanic trench
D. seamount
Answer
The
answer is B. The other
features lie beyond the
continental slope.
Question 3
What
is the area in an ocean
basin where new ocean floor
is forming?
Answer
New
seafloor forms at midocean ridges as lava erupts
through cracks in Earth’s
crust.