Introduction to the Ocean Floor

Draw

Draw a picture of what you think the ocean floor looks like.

Open Ended

How do you think scientists were able to tell us what the ocean floor looks like when the ocean is so deep?

Ocean

Topography

Topography

Topography is the study of elevation of land and its
natural features.

Oceanographers use sonar to help plot the elevation
of the ocean floor.

Sonar works by measuring the time it takes a pulse of
sound to go from a ship to the ocean floor & echo
back to the ship commonly referred to as echo
sounding.

In the 1920's, a
new technique-

SONAR- was

developed. Sound

Navigation &

Ranging- provides a

rapid method of
looking through
water to identify
features in the
water beneath a

vessel & on the sea
floor. Before then
little was known
about the ocean

floor.

Sonar

Seamount &

Mid-ocean Ridge

Underwater mountains that do not reach the surface
are called seamounts.

Seamounts usually form where 2 plate tectonics meet.

A chain of mountains where tectonic plates meet is
known as mid-ocean ridges.

Seamount &

Mid-ocean Ridge

Seamount &

Mid-ocean Ridge

Seamount &

Mid-ocean Ridge

The map above shows the arrows were plates are moving apart,

together, or side to side. As they move magma escapes creating a range

of mountains called a mid-ocean ridge.

Trench

A trench is a long, deep valley on the ocean floor
through which old ocean floor sinks back toward the
mantle.

Trenches are the deepest part of the ocean.

The Marianas Trench in the Pacific Ocean is the
world’s deepest trench.

Trench

Continental

Shelf & Continental Slope

The continentalshelf is a gently sloping, shallow area
that extends outward from the edge of each
continent.

Light from the sun allows plantlife to exist on the
Continental Shelf.

After the continental slope, the continental shelf
begins to slope downward.

Continental

Shelf & Continental Slope

Abyssal

Plain

The AbyssalPlain is the smooth, nearly flat region of
the ocean floor.

It is covered with thick layers of mud and silt.

Majority of the ocean floor is an abyssalplain.

The flattest places on Earth are abyssal plains.

Abyssal

Plain

Abyssal

Plain

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