2. Partner Reading Take out your spiral notebook. Open your textbook to page 75. Read pages 75-82 Pair up with one other person Each reads 2 paragraphs As you read, write the definitions of the following terms in your spiral notebook. Salinity Density Oceanographer Name the 3 layers of the ocean divided by temperature – define each and tell depth of each layer. (pg. 79) Continental shelf Continental slope Seamounts Mid-ocean ridge Sonar Satellite imaging

3. 3.1: Ocean water covers much of the Earth 71% of earth is seawater. Earth formed 4.6 billion yrs ago. Water vapor condensed making the oceans

4. Ocean water contains salts and gases: Every 1000 grams of seawater contains 35 gms. of salt. Salinity: measure of the amount of dissolved salt in water. Where does the ocean get its salt? * Rocks and minerals – rain wash them into the ocean. * Eruption of underwater volcanoes.

5. Salt is added and removed but oceans salinity has remained the same for 1.5 billion yrs. Salt water has greater density than fresh water. Density – measure of amount of matter packed into a given volume. Some oceans saltier than others because of evaporation, warm climates, and shallow areas. Some oceans are less salty – being diluted by fresh water, rivers, etc.

6. Oxygen and other Gases Ocean animals take in oxygen and give off carbon dioxide. Oxygen and CO2 get mixed into the ocean from the air and plants and algae that live near the surface. CO2 – building block of ocean animals shells.

7. Ocean Temperatures Vary: Oceanographers – people who study the ocean. Divide the ocean into 3 layers according to temperature. *Surface Layer: about surface to 300m. - heated by sun, warmest layer, less dense. *Thermocline: 300m to 700m. Middle Temp. *Deep water: below 700m. – cold all the time, anywhere – temp. is barely above freezing.

8. Ocean floor has many features: Continental Shelf: flat or gently sloping land underwater that extends from edge to slope of the continent. Continental Slope: land that drops down steeply at edge of shelf Seamounts – underwater mountains. Midocean ridge – chain of mountains that run through an ocean basin.

9. Mapping the Ocean Floor: Sonar – a system that uses sound waves to measure distances and locate objects. Ships aim waves at oceans bottom and measure time it takes to receive the echo: 1. Fast echo – bottom is shallow 2. Slow echo – bottom is deep

10. Satellite imaging – for mapping large areas of the Ocean: * Detect tiny bumps/dips in ocean * Shape of ocean floor.