Features of the Ocean Floor

• How do you imagine the ocean floor?

It may be a surprise but…..

The Ocean floor looks like this….

4 main features of the Ocean Floor

• 1) continental shelf –shallow area of ocean floor

• 2) continental slope-steep edge of the continental shelf that drops down at an angle

• 3) abyssal plain-smooth, flat region of the ocean floor that collects many deposits of dead organism remains

• 4) mid-ocean ridge-range of mountains that passes through all of Earth’s oceans that is caused by diverging plates

Continental Shelf

*A gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent*Extends about 130 meters*only about 7% of the entire ocean floor

Continental Slope• The steep edge of the continental shelf • Drops down at a sharp angle• Marks the true edge of a continent, where the

rock that makes up the continent stops and the ocean floor rock begins

Abyssal Plain • The smooth, nearly flat region of the ocean

floor • Has thick layers of sediment, formed by the

remains of dead organisms from the surface• Remember: FLAT REGION

Mid-Ocean Ridge

• A continuous range of mountains that winds around the Earth

• Passes through all of Earth’s oceans • Nearly 80,000 kilometers long • Longest mountain range on earth • Consists of many peaks along both sides of a

central valley

Mid-Ocean Ridge

Volcanic Islands

• When volcanoes on the ocean floor erupt, they can create mountains whose peaks break the surface of the ocean.

• As the lava cools, islands form

Fun Fact:

• The word “volcano” comes from the Roman mythical god, “Vulcan,” who was the God of Fire.

Volcano Terms

• When the hot liquid rock is still inside the volcano, it is called magma

• When the magma bursts from the volcano and is outside of the volcano, it is called lava

Seamounts

• Mountains whose peaks do not break the surface of the ocean water

Seamounts

• Mountains rising from the ocean seafloor that do not reach the water’s surface

• They are usually extinct volcanoes• Come in all shapes and sizes • Because of their elevation and the fact that

they do not erupt, they attract plankton, corals, fish, and marine mammals

Coral that could appear on a Seamount

What do PLATES have to do with the ocean floor?

• Plate movements have shaped many of the most dramatic features of the Earth, both on land and under the ocean.• Convergent cause trenches• Divergent caused the mid-ocean

ridge

Seafloor Spreading

• Plates “diverge” or move apart• Along the ridge, magma (lava) squeezes up

through the cracks, and as it hardens, it adds a new strip of rock to the ocean floor

Divergent Plates

Seafloor Spreading

Trenches• A dark gash in the ocean floor

Look for the Trench

Converging Plates

• When plates are pushed together, one plate sinks under the other (called subduction)

• In a TRENCH, old ocean plates converge and sink

Mariana Trench

• The deepest trench in the world and the deepest part of the world’s ocean

• 1,580 miles long• It is 6.8 miles deep • Pacific Ocean• The Mariana Trench is over 7,000 ft deeper than

Mount Everest is tall• Mariana Trench is more than five times as long

as the Grand Canyon