Exploring the Ocean

Why is the ocean difficult to study?

1. It is DEEP! 3.8 km (that’s twice as deep as the Grand Canyon)

2. It is DARK and COLD! (Only a few degrees above freezing)

3. It has extreme PRESSURE!

So, how did we map it?

SONAR: Sound Navigation and Ranging

Ships bounce sounds off the ocean floor and time how long it takes them to return to the ship.

What did they find?

1. Continental Shelf

2. Continental Slope

3. Abyssal Plains

4. Mid-Ocean Ridge

5. Seamounts

6. Trenches

Continental Shelf

• Looks like a flat shelf on the edge of a continent

• Ranges from 10km-350km wide

• Home of many ocean plants and animals because sunlight reaches the bottom.

Continental Slope

• Slope that reaches from the edge of the continental shelf to the ocean bottom.

• Steeper than the continental shelf.

Abyssal Plains

• Flat seafloor area at the bottom of the continental slope

• 4000-6000km deep

• Covered in decayed animal material

Mid-Ocean Ridge

• Underwater chain of volcanic mountains

• Location of seafloor spreading

Seamounts• Inactive volcanoes on the ocean floor.

(Some may be active near the mid-ocean ridge)

• Volcanic Islands: Seamounts that rise above the water

Trenches

• Mostly found in the Pacific Ocean.

• Deep valley on the seafloor where crust is returning to the mantle.

• Ex: Marianas Trench = deepest place in the Pacific Ocean. 11km deep. (Mount Everest could fit inside it!)

Name the features!

Here are the answers:

• A: Continental Slope

• B: Seamounts

• C: Abyssal Plain

• D: Mid-Ocean Ridge

• E: Volcanic Island

• F: Continental Shelf

• G: Trench