Features of the Ocean Floor

1. Features of the Ocean Floor Ms. Bridgeland 6th Grade

2. Features of the Ocean Floor • What do you think the Ocean Floor looks like? • Raise your hand if you think that it is flat? • Raise your hand if you think that it is uneven?

3. It is a surprise to many that theocean floor looks like this….

4. Features of the Ocean Floor continental shelf –shallow area of ocean floor continental slope-steep edge of the continental shelf abyssal plain-smooth, flat region of the ocean floor mid-ocean ridge-range of mountains that passes through all of Earth’s oceans

5. In Shallow Water: • Continental shelf • Continental slope: end of shelf and beginning of slope marks where continental rock ends & oceanic rock begins • Think of Nemo… “The drop-off!”

6. In Open Ocean: • Abyssal Plain: thick layers of sediment lie here, formed by remains of dead organisms • Mid-Ocean Ridge: mountain range along both sides of a central valley –this chain runs through all the oceans in the world • Remember this is where sea-floor spreading occurs magma erupts here and produces new ocean floor

7. Continental Shelf

8. Continental Shelf *Still considered to be part of the continents (continental rock) *Average width is 40 miles (65 km), but width varies ex. in parts of California = less than 1 km ex. along northern coast of Siberia = 1,290 km (800 miles) *only about 7% of the entire ocean floor

9. Continental Slope • Drops down at a sharp angle • Marks the true edge of a continent, transition from continental crust to oceanic crust • Extends from edge of continental shelf to the abyssal plain (between 100 -3,200 meters (330 -10,500 feet) • Most Pacific slopes are steeper than Atlantic slopes • About 8.5% of ocean floor is made up of continental slopes

10. 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

11. Abyssal Plain

12. Mid-ocean ridge • A continuous range of mountains that winds around the Earth • Formed by plate tectonics • 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 • Some mountains along the ridge reach above sea level, forming island groups (ex. Azores islands in Portugal)

13. Azores Islands –part of the mountains that make up the mid-ocean ridge

14. Mid-ocean ridge is several times longer than the Andes

15. Mid-Ocean Ridge

16. Seafloor Spreading happens at the Mid-Ocean Ridge • 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. Trench: A deep, steep-sided canyon or “hole” in the ocean floor

18. Mariana Trench • The deepest trench in the world and the deepest part of the world’s ocean • Mariana Trench is more than five times as long as the Grand Canyon

19. Mariana Trench is deeper than Mount Everest is tall

21. Trenchesare formed by Converging Plates • When plates are pushed together, one plate sinks under the other

22. Converging Plates

23. Features of the ocean floor: Volcanic Islands

24. Volcanic Islands: • Appear on the abyssal plain • When they erupt, they create mountains whose peaks break the surface of the ocean • When lava cools, islands are formed

25. Volcanic Islands: Galapagos Islands (west of continental Ecuador)

26. Volcanic activity causes Galapagos Islands to have a unique climate with unique animals that live nowhere else in the world • http://video.nationalgeographic.com/video/galapagos-unique-animals-lex

27. Volcanic Islands

28. Volcanic Islands

29. Seamounts • Mountains whose peaks do not break the surface of the ocean water, and thus are NOT islands • Still formed by volcanic activity

30. Seamounts • Provide habitats for organisms • Nutrients are carried upwards toward the sunlit surface, providing food for creatures like corals, fish, & crustaceans

31. Seamounts