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
1. Pacific
DESCRIPTION
The Largest ocean. It flows between Asia and the Americas.
2. Atlantic
The second largest ocean. It’s volume is about half of the
Atlantic.
3. Indian
The third largest ocen
4. Southern
Extends from the coast of Antarctica to 60 degrees south
latitude.
5. Arctic
The smallest ocean, much of its surface is covered in 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 ( forced out in large amounts) 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?
Meanwhile, Earth was cooling. Earth cooled enough for water vapor to
condense.
8. How did condensed water vapor form the oceans?
This water began to fall as rain. 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 minerals on
land. … At the same time, water is evaporating from the ocean and is leaving
the dissolved solids behind.
13. The most abundant salt dissolved in the ocean is Sodium Chloride . Write down the
symbols next to the names of the two elements that make up this compound.
Sodium - Na
Chloride- Cl
14. Define “salinity”.
A measurement of the amount of dissolved salt in a given amount of water.
15. Describe how climate affects salinity.
Places with hotter , drier climates typically has a higher salinity. Coastal water
in cooler, more moist places typically has a lower 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?
Temperature increases the evaporation rate. Evaporation removes water but
leaves salt behind. … More fresh water from rivers and streams runs into the
ocean in these areas.
17. Explain how the movement of water affects salinity.
Parts of the open ocean that do not have currents running through them can
be slow moving. 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
Description
a. Surface Zone
b. Thermocline
c. Deep Zone
20. Explain why parts of the ocean along the equator are warmer than those closer to the poles.
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?
Nearly all of Earth’s water is in the oceans.
IV. A GLOBAL THERMOSTAT
22. What is the most important function of the ocean?
To absorb and hold heat energy from the sun. This function regulates
temperatures in the atmosphere.
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 the poles. As a result, the waters there
are warmer than waters at higher latitudes.
25. How does the circulation of warm ocean water affect the climate of some coastal lands?
Some coastal lands have warmer climates than they would have without the
currents.