THE OCEANS

Water, water everywhere…

• Oceans contain salt water
• The measure of how much salt is in water is called its SALINITY
• The most common salt is sodium chloride but there are many others (page 411)

For example:

magnesium, calcium, sulphate, potassium

Where does the ocean get its salt?

• Rocks are made of minerals or salts
• As rivers flow over the rocks, they erode salts from the rocks and carry them to the ocean
• As shells of dead and decaying organisms decompose, the salts in the shells return to the ocean
• Underwater volcanoes constantly release minerals into the ocean water

OCEAN FLOOR FEATURES

Remember Science 7…

• The Earth’s crust is composed of Tectonic Plates that move on top of a liquid mantle
• Converging boundaries: plates are moving towards each other
• Diverging boundaries: plates are moving apart
• Subduction: occurs when one plate is forced below another

Continental Shelf

• Between coast and start of the ocean basin
• Really just a submerged extension of the continent!
• Extend from less than 30 km to more than 300 km from shoreline
• Width of continental shelf depends on landforms close to the coast
• Mountains usually mean narrower shelf

Continental Slope

• Drops from the end of the continental shelf to the bottom of the ocean

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• Usually less than 200 km wide and drop about 3 km

Abyssal Plains

• Found between continental slope and mid-ocean ridges
• Underwater landslides bring large amounts of sediments to the bottom of the ocean
• Great mass of water causes sediments to be pressed into a long, flat plain.

Mid-Ocean Ridges

• Occur at Diverging plate boundaries in the “middle” of the ocean
• The sea floor spreads, causing molten lava to spill out
• Cold ocean water cools the rock and causes it to harden.
• More rock spills out, and piles up forming an underwater mountain range

Trenches

• Occur at subduction zones (only occur at converging plate boundaries!)
• Oceanic plate is forced below a continental plate, creates a trench

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• Some trenches are so deep they could completely submerge Mount Everest!

Putting it all together!

Assignment!

• Page 416 in your Textbook
• Mapping the Ocean Floor
• Use the worksheet you are given to make a graph of the information and answer the questions.
• DUE NEXT CLASS

WAVES… dude

• Basically just really big ripples on the surface of the ocean
• As wind blow across the surface, it creates a swell of water
• The energy of the wave, is passed from water molecule to water molecule.
• Water particles move in a circular motion to help the energy continue to transfer.

Wind Direction

Components of waves

crest

trough

Wavelength: the distance between two troughs or two crests

The GREATER the wavelength the lower the frequency

The SMALLER the wavelength the greater the frequency

Breakers

• As waves get closer to the shoreline, water particles come into contact with sand particles
• Friction between these particles slows the water particles down at the bottom of the wave.
• Water at the top of the wave continues to move quickly, causing it to topple over and break on the shorline.
• Breakers cause lots of erosion because of their increased energy.

Beaches

• Remember that there are always sediments present in the water
• When these sediments are deposited they can form beaches!
• Rough water – large stones and rock fragments, steep slopes
• Calm water – sandy, small pebbles, gentle slopes

More beaches…

• Winter: strong winds means larger waves

Larger waves have more energy to pick up sediments which leads to more erosion

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• Summer: less wind means calmer waves

Smaller waves have less energy to pick up sediments which leads to deposition

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• SO: Beaches are generally eroded in winter and built up again in the summer

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Prevention of beach erosion

• Seawalls & Breakwaters

Beach communities have tried many ways to prevent beach erosion

Prevention continued…

• Jetties

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• Groins

TIDES

• Slow rise and fall of ocean water
• Different than waves because they are caused by gravitational pull of the sun and the moon
• Tidal Range: difference between high and low tide
• Depends on landforms and relative location of Sun, Earth and Moon

Spring Tides

• Occur when the sun, moon and earth are all in one line
• Happens at Full Moon and New Moon
• Largest tidal range

Neap Tides

• When Sun and Moon are at right angles with each other
• Occur during First Quarter & Second Quarter
• Smallest tidal range

Tidal Range and landforms

• Gulf of Mexico – very small tidal range
• Small amount of water enters and spreads out to fill the bay

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• Bay of Fundy – very large tidal range
• Larger amount enters but is funneled in to smaller space

Ocean Temperature

• Mixed water

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• Thermocline

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• Deep water

Ocean Currents and Climate

Currents affect climate for two main reasons:

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1. Water has a high specific heat capacity

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2. Thermal energy moves from high to low

Gulf Stream

• Starts in Carribbean Sea – very WARM
• Ocean water is cooler than atmosphere so it absorbs thermal energy
• Travels to Great Britain
• Ocean water is now warmer than the atmosphere so it gives up thermal energy, warming the climate

Labrador Current

• Starts in the North Atlantic – Baffin Bay – COLD!
• Sweeps across Eastern Atlantic Canada
• Water is colder than atmosphere so it absorbs what little warmth there is resulting in a cold, dry climate.