Oceans. Seas of Life. What are Oceans?. List characteristics of the oceans: Large Waves Tides Salt water Plant and animal life Deep. What Are Ocean Waves?. Ocean waves are movements where water particles alternately rise and fall. How Do Waves Move?. Water waves have two motions:
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Oceans Seas of Life
What are Oceans? • List characteristics of the oceans: • Large • Waves • Tides • Salt water • Plant and animal life • Deep
What Are Ocean Waves? • Ocean waves are movements where water particles alternately rise and fall.
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.
Parts of Waves • Crest = the top of a wave • Trough = the bottom of a wave
How Are Waves Measured? • Wave Length (Frequency)= the distance from crest to crest. • Wave Height (Amplitude)= the distance from crest to trough.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.