Features of the Ocean Floor

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