1. Features of the Ocean Floor How do you imagine the ocean floor? It may be a surprise but…..

2. The Ocean floor looks like this….

3. 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

4. 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

5. 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

6. 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

7. 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

8. Mid-Ocean Ridge

9. 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

10. Fun Fact: The word “volcano” comes from the Roman mythical god, “Vulcan,” who was the God of Fire.

11. 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

12. Seamounts Mountains whose peaks do not break the surface of the ocean water

13. 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

14. Coral that could appear on a Seamount

15. 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

16. 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

17. Divergent Plates

18. Seafloor Spreading

19. Trenches A dark gash in the ocean floor

20. Look for the Trench

21. Converging Plates When plates are pushed together, one plate sinks under the other (called subduction) In a TRENCH, old ocean plates converge and sink

22. 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