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4-The Oceans. Ridges. Plates are moving away from each other This forms oceans ridges. On the other end, the plates are colliding and sub-ducting (being pushed underneath). Trenches. Trenches are formed by the subduction of the ocean plate underneath of the continental plate.
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Ridges • Plates are moving away from each other • This forms oceans ridges
On the other end, the plates are colliding and sub-ducting (being pushed underneath).
Trenches • Trenches are formed by the subduction of the ocean plate underneath of the continental plate.
Abyssal plains • Sediment is deposited in oceans by rivers and they are spread evenly by earthquakes and ocean currents.
Continental Shelf • Submerged part of the continent in the ocean. This is not part of the ocean basin.
Continental shelves have a gradual slope • Continental slopes have a steep slope
How Waves are Formed • Ocean waves are large ripples set in motion by steady winds
Crest – • Trough – • Wavelength –
How Beaches are Formed • Waves will increase in height and shorten wavelength when it approaches the shore.
This is due to friction against the wave as the water becomes more shallow
Why does one shoreline have a sandy beach and another does not?
Waves usually hit the shoreline at slight angles • This creates a longshore current that runs along the shoreline.
What happens if a longshore current isn’t carrying all the sand it has the energy to carry?
Waves will erode rocks and pebbles into finer grains of sand.
Steep shorelines carry the light sediment back into the water leaving rocks behind.
Seawalls and breakwaters slow down the speed and forces of waves.
Tides • Beaches covered and uncovered in regular daily cycles.
Spring tides are the largest tidal movements because the sun and moon are in alignment.
Neap tides are the smallest tidal movements because the moon and sun are at right angles to each other.
Two bulges occur. • 1. first bulge is on the side the moon is facing the earth. The moon pulls on the ocean.
2. second bulge occurs on the opposite side of the earth because the moon pulls more strongly on the earth than the ocean on the opposite side
Ocean Currents • Surface currents result in major wind patterns
3 factors influence the direction of winds and surface currents:
Uneven heating of the atmosphere • Warm air rises which creates an area of low pressure • Cool air with high pressure moves in creating wind.
2. Rotation of the Earth • Cool air rushes in from the poles to the equator and the rotation of the earth pushes the winds in westerly direction.
3. The continents • They will deflect the winds so that the currents now circulate in a circular motion
Currents will flow to change climates. • Ie: Britain and Hudson Bay area. • Pg. 429 Fig. 5.70