Handout 19-2

Features of the Ocean Floor

1. The shallow sea floor between the shoreline and the deep-ocean bottom is called the

• a. continental margin.

2. Continental margins are made up of continental crust

• b. and a thick wedge of sediment.

3. The part of the continent covered by water is called the

• c. continental shelf.

4. The continental shelf slopes gently from the shoreline, and drops about 0.12 m every

• b. 100 m.

5. the average depth of the water covering a continental shelf is about

• b. 60 m.

6. The continental shelf is part of the• a. continental margin.

7. V-shaped valleys in the continental shelf and continental slope are called ___________.

• submarine canyons

8. What is one place submarine canyons are often found?

• Near the mouth of major rivers.

9. How can turbidity currents help form submarine canyons?

• Turbidity currents carry sediment down the continental slopes.

10. How do turbidity currents form?

• When earthquakes cause underwater landslides

• When large sediment loads run down a slope

11. What is the name of the deepest place in Earth’s crust?

• The Mariana Trench

12. Where is the deepest place in Earth’s crust located?

• The Western Pacific Ocean

13. About how deep is the deepest place in Earth’s crust?

• More than 11,000 meters deep– 36,089 ft.– 6.8 miles

14. In the deep-ocean basins, what is a trench?

• A long, narrow and steep depression that forms on the oceanfloor.

15. How do trenches form in the deep-ocean basins?

• Trenches form in deep ocean basins as a result of subduction of a tectonic plate.

16. About half of the deep-ocean basins are covered by _______ ___.

• Abyssal plains

17. The flattest regions on Earth are ____________• Abyssal plains

18. Layers of fine _________ cover the abyssal plains.

• sediment

19. How does the age of the oceanic crust affect the thickness of sediments on the abyssal plains?• Older crust is generally covered with thicker

sediments than younger.

20. The most prominent features of ocean basins are _________.

• mid-ocean ridges.

21. Mid-ocean ridges form underwater ________.

• mountain ranges.

22. What is one place where a mid-ocean ridge rises above sea level?

• Iceland

23. Where do seamounts form?

• Near hotspots• Areas of increased volcanic activity

24. guyot

25. hot spot

26. seamount

27. atoll

28. oceanic island

a. an area of increased volcanic activity where seamounts formb. submerged seamount with a flat topc. a seamount that rises above the oceand. an oceanic island that is in the process of being eroded into a guyote. submerged volcanic mountain taller than 1 km

The End!!!