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The Ocean Floor

The Ocean Floor. What is on the ocean floor?. The ocean floor has similar features to the surface of the Earth where we live. Mountains, valleys, volcanoes The features of the ocean floor are very big, with deep trenches and tall mountains – it sort of looks like a rollercoaster.

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The Ocean Floor

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  1. The Ocean Floor

  2. What is on the ocean floor? • The ocean floor has similar features to the surface of the Earth where we live. • Mountains, valleys, volcanoes • The features of the ocean floor are very big, with deep trenches and tall mountains – it sort of looks like a rollercoaster.

  3. What have scientists discovered about the ocean floor? • Scientists have used echo sounding to figure out the topography of the ocean floor • Topography is the surface of land. In this case we are taking about the land beneath the ocean.

  4. Continental Shelf • Gently sloping shelf of land extending from the shoreline to the continental edge

  5. Continental Slope • A sharp underwater hill that connects the continent to the ocean • The way the continental slope looks matches the continental shelf • If the continental slope is rocky, the continental shelf is rocky too Check for Understanding: What would the continental shelf look like if the continental slope was smooth?

  6. Continental Rise • A gently sloping hill that connects the continental slope to the ocean floor. (This is where you are no longer on the continent) • The continental rise is created by the deposition of sediments • The height of the continental rise can increase if a storm or intense waves cause a lot of erosion and deposition!

  7. Submarine canyon • A steep V-shaped canyon that cuts through the continental shelf and continental slope. • Some submarine canyons are bigger than the Grand Canyon!!

  8. Abyssal Plain • The flat smooth part of the deep ocean floor • Extremely dark – no sunlight can reach here! • Challenge: What do you think this means for plants?

  9. Ocean Trenches • Valleys cut deep into the ocean floor. • This is the deepest part of the ocean floor.

  10. Seamount • A steep, pointy extinct volcano. • Basically it is a tall underwater mountain.

  11. Guyot • A seamount that has a flat top • The top is flattened by the action of waves

  12. Mid Ocean-Ridge • An undersea mountain range. • DO YOU remember how this is formed??

  13. Rift Valley • A deep valley in a mid-ocean ridge that is formed when the sea floor is pulled apart. • WHAT CAUSES THE SEAFLOOR TO SPREAD APART?? rift-valley is IN the mid-ocean ridge

  14. Check for understanding! • http://www.classzone.com/books/earth_science/terc/content/investigations/es2301/es2301page03.cfm?chapter_no=investigation

  15. Because it is impossible to see the sea floor, scientists use a technique called echo sounding Echo Sounding is how long it takes a sound wave to go from a ship to the sea floor and back to the ship Echo Sounding

  16. So how does sound echoing happen? Videos: • http://www.youtube.com/watch?v=yFu2676bc6g • http://player.discoveryeducation.com/index.cfm?guidAssetId=4F6C5920-9267-41B4-9DA0-1C532229B567&blnFromSearch=1&productcode=US Check for understanding: in 1-2 COMPLETE sentences—summarize what sound echoing or sonar echoing is and what is it used for.

  17. How deep is the Ocean? • Check for understanding: Which ocean is the deepest ocean? • Sound waves travels 1,520 m/s in sea water. • So, if a pulse of sound waves makes a round trip in 2 seconds, then it has traveled 1,520 meters to the bottom of the ocean & back up to the surface. • To find the depth of the ocean at any point, scientists measure the time of the round trip in seconds, multiply that by 1,520 m/s and then divide that by 2.

  18. Questions: Waves (pings) from an echo sounder aboard a ship make a round trip in 8 seconds. How far beneath the ship is the ocean floor? Another ship records waves (pings) that make a round trip in 20 seconds. How far beneath the ship is the ocean floor? Answers: _____________ _____________ Tell me how deep the ocean is!

  19. Deep Sea Ocean Adventure—Calculation Lab! • We are going Magic School Bus style—down to the bottom of the ocean. • We are going 9,000-10,000 meters into the ocean to see the ocean floor! • What kind of scary sea animals will we run into? In pairs calculate the depth of each creepy crawly ocean animal to find out which animals we will be swimming with.

  20. Challenge/Check for Understanding: A scientist sends out Sound wave A that takes 9 seconds to echo back. A second sound wave B takes 14 seconds to echo back. • Which sound wave hit a deeper part of the ocean? (circle one) A or B • Which sound wave (A or B) found an Abyssal Plain? __________________ • Which sound wave (A or B) found a Ocean Trench? ____________________

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