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Science Chapter 2 Oceans Outline
I.
II.
Ocean Water
 Water covers about75% of Earth (almost all of that is Oceans)
 Ocean Water is salty, but provides a large amount of the Earth’s fresh water
A. The Water Cycle
1. Heat from the sun causes fresh water to evaporate from oceans, leaving the
salt behind.
2. The evaporated water condenses to form clouds
3. Fresh Water falls from the clouds to Earth’s surface as rain.
*During the water cycle, water changes from a liquid to a gas and back to a liquid*
B. What is in Ocean Water?
1. Ocean water is a mixture of water and many dissolved solids. Most of these
solids are salts.
a. Most of the salts and other substances in the ocean come from the
land
2. Near places where rivers empty into the ocean, the ocean water is less salty
than it is farther from the shore.
a. Ocean water is saltier near the equator where it is hot and water
evaporates faster
b. Ocean water is less salty near the North and South Poles, where it is
colder and water evaporates more slowly
Ocean Movements
C. Waves
1. A wave is the up-and-down movement of the water particles that make it up
a. Caused by the wind
b. Wind pulls on the water particles
c. This causes small bumps or ripples of water to form
d. As wind continues, ripples keep growing and become waves
2. The height of waves depend on:
a. The strength of the wind
b. The amount of time the wind blows
c. The size of the area over which the wind blows
3. Strong gusty winds blowing over an area of many square miles can cause a
large wave called a storm surge
a. These occur during hurricanes and can cause a lot of damage along a
shore
4. Waves change the shore
a. Erosion- water carries sand and other sediments back to the ocean
 Beaches get smaller
b. Deposition- waves give up their energy and deposit, or drop sediments
 Beaches get bigger
5. Parts of a wave
D. Tides
1. Tides are the daily change in the local water level of the ocean
a. At high tide, much of the beach is covered by water
b. At low tide, waves break farther away from the shore
2. There are two high tides and two low tides each day
3. Tides are caused by gravity (a force that causes objects to be pulled toward all
other objects
The force depends on
a. The size of the objects (bigger objects have a greater pull)
b. The distance between them (closer objects have a greater pull)
4. The pull of the moon’s gravity on Earth is the main cause of ocean tides
E. Currents
1. Currents are rivers of water that flow in the ocean
2. Surface currents form when steady winds blow over the surface of the ocean
3. Deep ocean currents form because of density differences in ocean water
a. Density depends on
 Amount of salt
 Temperature
b. The more salt in the water, the denser it will be
c. Cold ocean water is denser than warm ocean water
4. Deep ocean currents form when dense, cold water meets less dense water. The
denser water flows under the less dense water, causing the less dense water to
rise.
Also use your copybook and any handouts to review
Test Date: ________________________