Oceanography

• Does water pressure increase of decrease with depth?

• Why is the surface temperature of oceans more variable than the water near the ocean floor?

• Why will a boat float higher in the Atlantic Ocean than it will in the Potomac River?

• What is the average concentration of dissolved salts in 1000 grams of ocean water?

Salinity (salt)

• 35% is the average concentration of dissolved salts in 1000 grams of ocean water.

• When sea water freezes, most the salt is left behind, increasing the density of the remaining seawater.

• Salinity tends to be above average in hot areas

• Which pair of factors would both cause salinity to increase? – Melting of sea ice and precipitation – Evaporation and freezing of sea water

Label the Oceans•Atlantic Ocean•Pacific Ocean•Indian Ocean•Arctic Ocean

Facts

• Phytoplankton is the base of the marine food chain and the primary energy source of marine ecosystems

• The zone in which the ocean temperatures change rapidly is called the?– Mixed layer– Seasonal layer– Thermocline

• Which of the following statements about ocean pressure is true?

• • A. Pressure increases with

temperature• • B. Pressure decreases with depth• • C. Pressure increases with depth• • D. The pressure is equal

throughout the ocean

• Why is the surface temperature of oceans more variable than the water near the ocean floor?

• • E. more energy is exchanged at the

surface• • F. more animals live near the surface• • G. water is less dense at the surface• • H. salt concentration is more

variable at the surface

Which pair of factors would both cause salinity to increase?

• • A. evaporation and freezing of sea

water• • B. freezing seawater and

precipitation• • C. precipitation and melting of sea ice• • D. melting of sea ice and evaporation

The two most common ions found in ocean water are

• • E. chloride and sodium• • F. potassium and calcium• • G. phosphate and nitrate• • H. magnesium and sodium

When seawater freezes, most of the salt

• • A.)is included in the ice,

increasing its density• • B.) is left behind, increasing the

density of the remaining seawater

• • C.) is included in the ice,

decreasing its density• • D.) is left behind, decreasing the

density of the remaining seawater

Salinity tends to be above average• • e. in areas of high precipitation• • f. where large rivers enter the ocean• • g. where icebergs are melting• • h. in hot areas

The base of the marine food chain and the primary energy source for marine ecosystems is

• • i. zooplankton• • j. phytoplankton• • k. bacteria• • l. salt

Questions/Answers• A boat will float higher in the Atlantic Ocean than it will in

the Potomac River because ocean water has ?– A lower freezing point– A greater density

• Why is the surface temperature of oceans more variable than the water near the ocean floor?– More energy is exchanged at the surface – More animals live near the surface

• Which of the following statements about oceans is true?– Pressure increases with temperature– Pressure increases with depth

The Water

• The two most common ions found in the ocean water are chloride and sodium

• Melting of polar ice caps will result in long-term changes in sea levels.

• Upwelling is important to ocean life because it brings nutrients to the surface water

• Major commercial fishing areas are located in areas of Persistent upwelling

Four Oceans

Atlantic Ocean

Indian Ocean

Pacific Ocean

Arctic Ocean

UPWELLING• Upwelling is important to ocean

life because it• • A. cools the surface water• • B. brings nutrients to the surface

water• • C. keeps ocean temperature

uniform• • D. brings carbon dioxide to the

surface

• Major commercial fishing areas are usually located in areas

• • e. where density currents form• • f. where seawater oxygen levels

are high• • g. of persistent upwelling• • h. that experience frequent

turbidity currents

Ocean Floor Questions

• What is the steepest region of a continental margin? • What is the flattest surface of Earth?• The continental slope is located at the end of the?• What is a cone-shaped undersea mountains of volcanic

origin that rises high above the ocean floor called?

• The steepest region of a continental margin is the

• • A. continental slope• • B. continental ridge• • C. continental rise• • D. continental shelf• •

• The flattest surface of Earth is a(n)• • e. island arc• • f. guyout• • g. seamount• • h. abyssal plain

• The continental slope is located at the end of the _____.

• • e. continental shelf • • f. ocean trench• • g. shoreline•• h. rift zone•

• All of the following ocean floor features indicate tectonic activity except

• • v. deep-sea trench• • w. mid-ocean ridge• • x. seamount• • y. abyssal plain

Mid-Ocean Ridge• Seafloor rocks near the mid-ocean ridge are older or younger then

the rocks far from the mid-ocean ridge??? • Mid ocean ridges are undersea mountain ranges where lithospheric

plates are moving apart and new oceanic crust is being formed.

Rip CurrentHow should a person escape from a rip current?

They should swim parallel to shore to escape the narrow current and let the waves carry you.

Convergent Boundaries

• Deep-sea trenches occur at convergent plate boundaries where one tectonic plate is sinking beneath another

• Suppose sound travels at an average rate of 1500 meters per second through seawater above a particular locationHow deep is the ocean if a sound pulse takes 10 seconds to reach the bottom and return to a surface ship?

• 150 meters• 300 meters• 7500 meters• 15000 meters

The Marianas Trench in the Pacific Ocean is 36,160 feet below sea level. This deep oceanic trench is caused by:

• A.) swift ocean currents eroding away the ocean floor

• B.) the collapse of an empty magma chamber in a large volcano

• C.) excessive boat traffic disrupting the normal sedimentation process

• D.) two tectonic plates colliding and one plunging below the other

Barrier islands form off the coast of the land. Where are most barrier beaches found in the U.S.?

Currents

• What causes a longshore current to form?• Turbidity currents move along the…?• Surface currents in the ocean are primarily

cause by?

Current Facts

• Surface currents flowing away from the equator carry warm water.

• The Gulf Stream current affects the weather in Virginia.

• The effect of the Earth’s rotation on winds and ocean currents is called the Coriolis Effect.

• Deep ocean current are driven by differences in density.

• Turbidity currents move along the bottom

• Surface currents in the ocean are primarily caused by winds.

• What causes a longshore current to form? – Waves striking the beach at

an angle rather than straight

More about currents• Deep ocean currents are driven by:A.) tidal forcesB.) differences in densityC.) differences in oxygen contentD.) changes in conveyor belt circulation• Which of the following is not a cause of ocean currents?A.) windB.) gravityC.) variation in water densityD.) type of seal life

Surface Currents

• Surface currents flowing away from the equator carry _____ water. In the northern hemisphere, surface currents tend to flow ________. Surface currents in the ocean are most commonly driven by ________.

-clockwise, warm, wind

Sun, Moon, and Earth• Tides are highest when

Earth is in line with both the sun and moon.

• When the Earth, sun, and moon are at 90 degree angles to each other, the tidal range is ______

• When the Earth, moon, and sun are lined up, what type of tide occurs?

Tide Facts and Terms

• What is most responsible for tides?

• What is the difference between the high and low tide water levels called?

Waves

• The lowest point of a wave is called the trough.• As a wave moves in shore and grows in height it

will eventually topple over, forming a breaker.• What causes the top of a wave to fall forward

when it moves in shore? Friction with the bottom

• The distance from crest to crest or trough to trough in a wave is the wavelength. Tsunami is a wave that would have a very long wavelength.

Waves

• Which of the following waves can have a very long wavelength?

A.) rip currentB.) tsunami C.) surface currentD.) upwelling current

You Answer• The lowest point of a wave is called thea.) crestb.) heightc.) troughd.) tideAs a wave moves in shore and grows in height it will eventually

topple over, forming a a.) messb.) tidec.) breakerd.) current

• What causes the top of a wave to fall forward when it moves to shore?

a.) friction with the bottomb.) storm surgesc.) upwelling currentsd.) wind