2. UNIT SEVEN: Earth’s Water  Chapter 21 Water and Solutions  Chapter 22 Water Systems  Chapter 23 How Water Shapes the Land

4. Chapter Twenty-Two: Water Systems  22.1 Water on Earth’s Surface  22.2 The Water Cycle  22.3 Oceans

5. Chapter 22.3 Learning Goals  Discuss the effects of temperature and salinity on Earth’s oceans.  Distinguish features of the ocean floor.  Compare and contrast the effects of surface currents and deep ocean currents.

6. 22.3 Oceans  Ocean water is about 3.5 percent salt.  The word salinity is a measure of the dissolved salts in water.  Most of the salt in ocean water is sodium chloride.

7. 22.3 Oceans  In some places, special ponds called salt evaporation ponds harvest salt from the ocean.

8. 22.3 Oceans The salt in the oceans comes from:  minerals in the ocean floor,  gases released by volcanoes, and  rivers that carry dissolved minerals out to sea.

9. Can you name Earth’s five oceans?

10. 22.3 Importance of oceans  Oceans are an important source of water for the water cycle.  Oceans spread energy and heat from the hot equator to the colder poles.  Phytoplankton produce most of the oxygen in the atmosphere.

11. 22.3 Oceans and Earth’s climate  The oceans are able to store heat energy.  The water on Earth prevents the planet from getting too hot or too cold.

12. 22.3 Oceans and Earth’s climate  The climates on the coastline are milder than they are inland because ocean-warmed air masses move over the oceans toward the land.

13. 22.3 Oceans and Earth’s climate  The climates on coastlines are milder than they are inland because ocean- warmed wind and air masses move over the oceans toward the land.

14. 22.3 Surface currents and gyres  The Sun’s unequal heating of Earth and the Coriolis effect cause permanent global wind patterns.  Surface ocean currents to form large rotating systems called gyres.

15. 22.3 Surface currents and gyres  One well-known current is the Gulf Stream.  Europe has mild winters due to both prevailing westerlies and the heat energy of the Gulf Stream.

16. 22.3 Deep ocean currents  Deep ocean currents move below the surface of the ocean.  They are slower than surface ocean currents.

17. 22.3 The ocean floor  Many of the important features of the oceans are hidden in deep water.  The continental margin is the region around continents that includes the:  continental shelf,  continental slope, and  continental rise.

18. 22.3 The continental shelf  Sand drifting down the steep face of a continental shelf cuts into the shelf just like streams cut into valleys.

19. 22.3 Features of the ocean floor  Maps can show the location of the continental shelf.  The true ocean floor is called the abyssal plain.  It is flat and smooth because a thick layer of sediment covers its features.

20. 22.3 The deep ocean floor  A barrier island is a low, sandy island that lies parallel to the shoreline.  A bank is a low, flat region on the continental shelf.  A seamount is a steep-sided mountain that rises from the ocean floor.

21. 22.3 The deep ocean floor  A guyot is a seamount that has eroded so that it has a flat top and is underwater.  Mid-ocean ridges mark places where two tectonic plates are separating and new ocean crust is being made.  Deep-ocean trenches are the deepest parts of the ocean.

23. Investigation 22C  Key Question:  How do temperature and salinity cause ocean layering? Global Winds and Ocean Currents

24. Rip Currents  More than 80% of water rescues performed by surf beach lifeguards are due to rip currents.  Rip currents are sometimes called riptides, or undertow. Learn why these two terms are misleading.