NAME______DATE______PERIOD______
EARTH’S OCEANS
DIRECTIONS: Read pages 374-381 in your textbook and answer the questions below.
I. DIVISIONS OF THE GLOBAL OCEAN
NAME / DESCRIPTION1. Pacific / The largest ocean(It flows between Asia and the Americas)
2. Atlantic / The second largest ocean (about half the volume of the Pacific)
3. Indian / The third largest ocean
4. Southern / Extends from the coast of Antarctica to the 60 degree south latitude
5. Arctic / The smallest ocean (much of the surface is covered by ice)
II. HOW DID THE OCEANS FORM?
6. Describe what the Earth was like 4.5 billion years ago.
There were no oceans. Volcanoes spewed lava, ash, and gases all over the planet. The volcanic gases began to form Earth’s atmosphere.
7. What happened to water vapor in the atmosphere when the early Earth cooled?
The water vapor began to fall as rain.
8. How did condensed water vapor form the oceans?
The rain filled the deeper levels of Earth’s surface, and the first oceans began to form.
9. The oceans were one giant body called ______Panthalassa______.
10. Place the following statements in historical order by writing the correct number (1,2,3, or 4) in the
space provided.
____4___ All oceans except the Pacific are expanding.
____3___ The South Atlantic Ocean was much smaller than it is today.
____1____ The Earth had one giant body of water, Panthalassa, and one giant landmass, Pangaea.
____2____ The Indian Ocean and the North Atlantic Ocean began to form as Pangaea broke apart.
III. CHARACTERISTICS OF OCEAN WATER
11. Write the name of the salt found in the ocean. It is the same kind of salt we sprinkle on our food!
sodium chloride
12. Describe how salts have been added to the oceans for billions of years.
As rivers and streams flow toward the oceans, they dissolve various materials on land. The running water carries these dissolved minerals to the ocean.
13. The most abundant salt dissolved in the ocean is ____sodium chloride. Write down the
names and symbols of the two elements that make up this compound.Sodium, Na and Chlorine, Cl
14. Define “salinity”.
A measure of the amount of dissolved salts in a given amount of
liquid
15. Describe how climate affects salinity.
Some parts of the ocean are saltier then others. Areas with hotter, drier climates typically have high salinity and areas with cooler, more humid climate have low salinity
16. Why does coastal water in places with hotter, drier climates typically have a higher salinity than
coastal water in places with cooler, more humid climates?
Coastal water in places with hotter, drier climates has a higher salinity because less fresh water flows into the ocean in drier areas and because heat increases the evaporation.
17. Explain how the movement of water affects salinity.
Slower-moving areas of water develop higher salinity.
18. The temperature of ocean water __decreases___ as depth increases.
19. Temperature Zones in the Ocean
Temp. Zone / Descriptiona. Surface Zone / The surface zone is the warm top layer of ocean water. It can extend to 300 m below sea level. Sunlight heats the top 100 m of the surface zone. Surface currents mix the heated water with cooler water below.
b. Thermocline / The second layer of ocean water. It can extend from 300 m below sea level to about 700 m below sea level. In the thermocline, temperature drops with increased depth faster than it does in the other two zones.
c. Deep Zone / The bottom layer that extends from the base of the thermocline to the bottom of the ocean. The temperature in this zone can range from 1⁰ C to 3⁰ C
20. Explain why parts of the ocean along the equator are warmer than those closer to the poles.
The parts of the ocean along the equator are warmer because they receive more direct sunlight per year than areas closer to the poles.
21. Why is the ocean an important part of the water cycle?
Because nearly all of Earth’s water is in the ocean and the water cycle is the continuous movement of water from the ocean to the atmosphere to the land and back to the ocean.
IV. A GLOBAL THERMOSTAT
22. What is the most important function of the ocean?
To absorb and hold energy from sunlight
23. The ocean absorbs and releases thermal energy much more slowly than dry ____land_ does.
24. Why are waters at the equator warmer than waters at higher latitudes?
The sun’s rays are more direct than at higher latitudes
25. How does the circulation of warm ocean water affect the climate of some coastal lands?
The circulation of warm water causes some coastal lands to have warmer climates than they would have without the currents.
Ex) Western Europe gets warm air from the gulf stream.