The Earth’s OceansA Dynamic System where many

physical and chemical changes are taking

place!

Ocean Bottom

The World’s Oceans•71% of the surface of the Earth is ocean•97% of all the Earth’s water is found in the oceans•The Atlantic, Pacific, and the Indian oceans are the major oceans•The Arctic Ocean, Mediterranean Sea, and the Caribbean Sea are part of the Atlantic Ocean•The Pacific Ocean is the largest and the deepest•Followed by the Atlantic Ocean, the Indian Ocean is deeper

Mapping the Ocean Floor•1872 the Challenger sailed from England, it remained at sea for three and a half years. It used wire to measure ocean depths. The Challenger collected animals and water samples from the ocean floor. It used special thermometers to record temperatures on the ocean floor.

•In 1920 the German ship Meteor used sonar for the first time to map the seafloor.

•Today the satellite Topex/Poseidon orbits the Earth using side scan sonar to map the bottom of the ocean

Mapping the Ocean•Mapping the bottom of the ocean can only be done by indirect methods, such as echo sounding, radar, sonar, and seismographic surveys

The Ocean Floor•Continental margin consist of the continental shelf, continental slope, and the continental rise•Continental shelf is the relatively flat area along the edge of every continent: it ranges from almost nothing to 1200 kilometers, the best fishing, large mineral deposits, and petroleum are found there

•Continental slope is at the edge of the continental shelf where the sea floor may plunge steeply 4-5 kilometers•Marks the boundary between the continental crust and the oceanic crust

•Continental rise is the area between the continental slope and the ocean floor•It is made of sediments that wash down from the continental shelf•Turbidity current carry large amounts of these sediments in masses of moving water, it is like an underwater avalanche

•Submarine canyons are deep V shaped valleys cut through the continental shelf and slope

Features of the Ocean Floor

Abyssal Plain• Large flat areas on the bottom

of the ocean• Atlantic and Indian oceans

have largest abyssal plains because almost all the worlds major rivers flow into them producing a large amount of sediment deposits in the plains

Seamounts and Guyots• Seamounts are underwater

volcanic mountains• They have steep sides and

narrow summits and rise more than 1000 meters above the sea floor

• When seamounts rise above the surface of the ocean they become islands

• Guyots are seamounts that do not rise to a peak or have eroded tops

Midocean Ridges•Largest mountain ranges on the Earth•These are formed where the plates are pulling apart•Rift valleys run along the middle of the midocean ridges

Trenches•The deepest part of the ocean found along edges of sea floor•Long narrow crevices that can be 11,000 meters deep•Deepest trench is the Mariana Trench in the Pacific Ocean that is more than 11,000 meters deep

Hydrothermal Vents•Openings into the mantle of the Earth where sea water seeps down and returns to the ocean

Hydrothermal Vents

Reefs•Reefs are large masses and ridges of limestone rocks produced by the shells of animals•There are three types of coral reefs: fringing reefs touch the shoreline of a volcanic island

Coral Reefs (cont)•Barrier reefs that are separated from the shore by an area of shallow water called a lagoon

Coral Reefs (cont)•And an atoll that is a ring of coral reef that surrounded an island that has beenworn away or sunk

This is the easy part!!!!!

The Water Cycle•The ocean is a source of fresh water for all living things

Temperature of Ocean Water•The sun is the major source of heat for the ocean•Surface zone -100-300 meters deep, temperature fairly constant, waves and surface winds mix the water and transfer the heat downward

Temperatures (cont)•Thermocline- found directly under the surface zone, temperature drops rapidly, less dense warm water floats on top of the more dense cold water

Temperature (cont)•Deep zone- has extremely cold water, extends from the thermocline to depths of 4000 meters or more, temperature decreases only slightly•Temperature below 1500 meters is only 4°

Temperature•The three ocean zones are not found in the Arctic or Antarctic•The surface temperatures are always very cold

Important Feature! Upwelling•When the cold currents get near the coast they force up nutrient rich water to the surface, this is called upwelling•Upwelling is important because it produces rich fishing grounds and plentiful food for marine life

And you thought the ocean was just for fun!!!!!!!

Oceanography TwoTemperature Zones, Waves, and Currents

Tides• These are the regular rise and

fall of ocean water caused by the gravitational pull between the moon and the Earth

• A bulge occurs in the ocean nearest the moon, this is the high tide and in the opposite is the low tide

• There are two high tides and two low tides a day

• Spring tides are high tides higher than other high tides and neap tides are low tides lower than other low tides

Moving Ocean Water•Waves are pulses of energy that move through the ocean•They carry energy, not matter•They begin as wind stirred ripples on the surface of the water•The greater the wind, the greater the wave

Wave Formation•The height of the wave depends on wind speed, the length of time the wind blows, and the distance the wind blows•Increasing any of these can increase the size of the wave

Wave Trivia•The highest wave every noted was 34 meters high in 1933 during a wind storm in the Pacific

Wave Characteristics•The crest is the highest part of the wave•The trough is the lowest part to the wave•Wavelength is measured from crest to crest or trough to trough

Waves (cont)•Waves are more destructive in the winter•Tsunamis is a giant wave caused by earthquakes

Currents•Currents can be described as “rivers” in the ocean•Two factors cause currents: wind patterns and water density differences

Surface Currents• Currents caused by winds are

surface currents found at a depth of several hundred meters

• There are warm and cold water currents, depending on where they come from

• These are called long-distance currents

• These currents form a continuous world wide pattern of water circulation

Deep Currents• Deep water currents are caused

by the differences in water density

• Cold water and saltier water is more dense

• Deep currents usually flow in the opposite direction of surface currents

• The densest water in the world is found in Antarctic, this current flows northward toward the equator at the same time warm current flow toward Antarctic

Deep Currents (cont)•When the cold currents get near the coast they force up nutrient rich water to the surface, this is called upwelling•Upwelling is important because it produces rich fishing grounds and plentiful food for marine life

Properties of Ocean Water•Ocean water is a mixture of gases and solids dissolved in pure water•Oceanographers believe that ocean water contains all of the natural elements found on Earth•All but 5 have been found

Salts in Ocean Water•Salinity is the amount of dissolved salts in ocean water•Sodium Chloride is the most common salt•Average salinity of the ocean is 35 o/oo•Salt comes from volcanic activity, erosion of the land, and wave erosion of beaches

Sea saltsParts per Thousand

chloride 19.3 o/oo

sodium 10.7 o/oo

sulfate 2.7 o/oo

magnesium 1.3 o/oo

calcium 0.4 o/oo

potassium 0.4 o/oo

bicarbonate 0.15 o/oo

bromide 0.07 o/oo

other 0.06 o/oo

Total Salinity

35.08 o/oo

Salinity•Salinity can be greater or less than the average of 35 o/oo•Lower salinity where freshwater rivers enter the ocean•Salinity is higher where there is greater evaporation and in polar regions where only fresh water freezes•Animals using certain salts to build their shells can lower salinity

Gases in Ocean Water•Nitrogen, carbon dioxide, and oxygen are the most abundant gasses found in ocean water•Oxygen and carbon dioxide are essential for plant growth•There is more gas found at the surface of the water where plant growth occurs

Deep Cold Water•Cold water holds more gas than warm water•When the colder denser water sinks to the bottom it carries oxygen rich water that aids in the survival of deep water species

Ocean Life Zones•Plant and animal life in the ocean is affect by three factors: amount of sunlight, temperature, and pressure•Plants and animals can be classified into three major groups according to their habitats of the water in which they live

Plankton•Largest group of animals and plants that float at or near the surface•These get the most sunlight•Found at depths of 1 to 200 meters deep•Very small organisms (plankton that whales eat)

Nekton•Contains all forms of organisms that swim around•They can actively search for food, prey or predators•These are found in all areas of the ocean

Benthos•Organisms that live on the ocean floor•Benthic plants live in shallow water so they can get the necessary sunlight•Oysters, crabs, starfish are all benthic•Some even live in the deepest parts of the ocean

Plankton, Nekton, and Benthos

Ocean Environments (Zones)•The classification of the ocean into life zones is based on the conditions of the ocean-conditions that vary widely

Intertidal Zone•The region that lies between low and high tide•Organisms must be able to live without water some of the time•They must find someway to attach so they are not washed out when tide goes out•Includes anemones, crabs, mussels, and plants

Neritic Zone• Extends from the low tide line to

the edge of the continental shelf• Depth of about 200 meters• Receives plenty of sunshine• Pressure is low and temperature

is constant• Plankton, nekton, and benthos

plants and animals are found here

• Riches part of the sea: contains fish, clams, snails, some smaller whales, and lobsters

• Much of the seafood we eat is found here!

Open-Ocean Zones• Bathyal zone begins at the

continental slope and ends about 2000 meters

• Sunlight cannot penetrate to the bottom

• Squid, octopus, and large whales are found here

• Abyssal zone extends to over 6000 meters

• No sunlight can penetrate, high pressure and low temperatures

• Most animals are small and strange!

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