1. Saltwater Systems oceans & seas cover 75% of the Earth’s surface
and contain 97% of the world’s water
ocean water is saline, with about 3% salt
salinity is the amount of dissolved salt in liquid
seas are smaller than oceans and tend to be surrounded by land

2. The world’s oceans can be divided into 5 regions:

3. Ocean Basins ocean basins are huge!
they have mountains, valleys and vast plains
they are formed mainly from movement of tectonic plates
as they move apart ocean basins expand
as they move together ocean basins shrink
the average depth of the oceans is 4,000 m
the deepest place is Marianas Trench at about 11,000 m
Ocean Ridges from magma coming to surface in middle.
Ocean Trench where one plate descends below another.

4. where plates pull apart magma can come to the surface and create mountains or ridges (e.g. Hawaiian Islands)
where one plate slides under another a trench is often formed (e.g. Marianas Trench)

5. The ocean basin does not begin at the shoreline… it begins at the lower edge of the continental slope.
the continental shelf and slope can be more than 300 km wide… that’s like from here to Edmonton

6. Ocean Temperature and Depth
The Sunlight Zone
The Twilight Zone
The Midnight Zone
ocean water also mixes from top to bottom
colder water is less dense because it can hold less salt
therefore it tends to rise up and mix with warmer water carried by surface currents
The Abyss

7. Ocean Waves Energy Direction
Ocean waves are just large ripples set in motion by steady winds.
Height depends on how fast, long and far with wind blows over the water.
Normal winds give waves 2 – 5 m high… hurricane winds give waves 30 m high.
Smooth waves are called swells.

8. The wave collapses onshore in a tumble of water called a breaker.
When Waves Hit Shore
Energy Direction
wave changes shape as it approaches shore
- lower part of water is slowed down by friction on ocean bottom
- upper part of water keeps going faster… and so tumbles over the top
the tumble of water as the wave collapses onshore is called a breaker
The wave collapses onshore in a tumble of water called a breaker.

9. Changing Shorelines
waves approach shorelines at an angle and create a current along the shoreline
waves erode and deposit sediments along the shore … creating interesting landscapes

10. Tides tides are regular cycles where ocean water levels rise and fall
they are caused by the moon’s (& sun’s) gravitational pull on the water
the moon rotates around the Earth and so its distance from oceans changes in 24 hours
when the moon is closest to the ocean it will have high tide
when the moon is farthest from the ocean it will have low tide

11. spring tides are the biggest variation between high & low tide
very high when the moon & sun line up on the same side of the Earth and pulling together
very low when the moon & sun are on opposite sides of the Earth and pulling in opposite directions
neap tides are the smallest variation between high & low tide
moon’s gravitational pull is at right angles to the gravitational pull of the sun

12. Ocean Currents 5 major gyres
North Atlantic
North Pacific
OCEAN CURRENTS are continuous movement of ocean water
3 factors influence the direction of winds and surface currents:
uneven heating of atmosphere (more at equator) – air moves from warm to cooler
rotation of Earth – spins things into circular motion (turns clockwise in N, and counterclockwise in S)
position of continents – deflects things along shoreline
winds blowing east along the equator are called TRADE WINDS
winds blowing west in the polar regions are called WESTERLY WINDS
the movement of ocean currents are critical for movement of heat around the earth and gives areas on the coast a warmer, milder climate (e.g. Vancouver and Victoria)
South Pacific
Indian Ocean
South Atlantic

13. The Gulf Stream a current of warm water starts in the Caribbean Sea
flows north along the east coast of North America
then flows across the Atlantic Ocean to England
warm ocean current affect climate by transferring their heat to the atmosphere
because water has a high heat capacity (takes a long time to heat up or cool down) it acts as a heat reservoir in winter and so keeps nearby land warmer than if there were no water