Oceans

1. Oceans Seas of Life

2. What are Oceans? • List characteristics of the oceans: • Large • Waves • Tides • Salt water • Plant and animal life • Deep

3. What Are Ocean Waves? • Ocean waves are movements where water particles alternately rise and fall.

4. How Do Waves Move? • Water waves have two motions: • The forward progress of the energy of the wave. • The circular motion of the water particles as they rise and fall.

5. Wave Motion

6. Parts of Waves • Crest = the top of a wave • Trough = the bottom of a wave

8. How Are Waves Measured? • Wave Length (Frequency)= the distance from crest to crest. • Wave Height (Amplitude)= the distance from crest to trough.

12. How Do Waves Break? • In open water waves roll. • Waves break in shallow water as the bottom of the wave has friction with the ocean floor, but the top continues at the same speed.

14. Effects of Breaking Waves • Surf is the turbulent water caused by breaking waves. • Swash is the motion of water up the beach and backwash is the water running back down the beach and under the next wave. • Rip currents are strong narrow currents that flow straight out to sea through the surf zone.

19. Topography of the Sea Floor • The crust of the sea floor is covered in many places with layers of sediment. • Terrigenous sediment is land sediment that has settled on the ocean floor. • Pelagic sediment is sediment made up of fine-grained clays and skeletons of microscopic organisms. • This covers 75% of the ocean bottom and can take up to 50 years to settle. • Oozes are sediments of microscopic shells.

20. Oozes

21. Topography of the Sea Floor Continental Shelf is a gently sloping surface which extends under the ocean from the shoreline to a depth of about 100-200 meters. Continental Slope is relatively steep, extending downward as deep as 2 km from the shelf. Continental Rise is a wedge of sediment that extends from the lower part of the slope to the deep ocean floor.

24. Sea Floor Topography • Abyssal plains are the flat regions of the deep ocean floor at the base of the rise. • Submarine canyons are v-shaped valleys that run across continental shelves and down continental slopes. • Mid-ocean ridges are undersea mountain ranges in the ocean basins. • Trenches are deep ocean chasms parallel to the edge of a continent or island arc.

28. Sea Floor Topography • Seamounts are volcanic mountains rising 1000m above the ocean floor over a hot spot. • Guyots are volcanic islands that have stopped growing and have been flattened by wave action.

30. Atol

31. How Do Waves Form? • Waves generally form in one of three ways: • Wind • Underwater earthquakes • Large amounts of ice or land falling into the water.

32. How do Waves Form? Wind Waves • Waves are usually formed by wind creating friction with the surface of the water. • With high enough wind speed a wave forms. • Increased wind speed = increased wave height.

34. How Do Waves Form?Wind Waves continued • Fetch = the distance that wind blows over the surface of the water. • Increased fetch = increased wave height. • Therefore the largest waves form on the biggest bodies of water with the strongest, longest prevailing winds.

36. How Do Waves Form?Underwater Earthquakes • As underwater earthquakes shift the ocean floor, very large waves called tsunamis form as great amounts of water rise and fall around the fault line.

39. How Do Waves Form?Landslides • As large amounts of land/ice hit the water at one time, very large waves called mega-tsunamis form as great amounts of water is pushed out of the way.

50. Beaches • A beach is a strip of sediment (usually sand or gravel) that extends from the low-tide line to a cliff or zone of permanent vegetation. • The beach face is the section the waves are constantly pounding. • Just offshore there is usually a marine terrace, a wide, gently sloping platform that may be exposed at low tide. • The berm is the wave-deposited upper part of a beach that is usually dry.