Oceanography Section 1: The History of the Oceans Slide 2 The
Origins of Water Earth is the only planet that has water in a
liquid form. Earth is the perfect distance from the sun so its not
too hot or cold. Many people believe the liquid water on Earth
makes life possible. Over 70% of the Earths surface is covered with
water. Slide 3 The Origins of Water 1.Volcanic Cycling Theory: all
of the Earths water was released by volcanic eruptions. When
volcanoes erupt they release water vapor and other gases. The gases
caused the temperature of Earth to cool. Cooler temperatures caused
the water vapor to turn into liquid. There are two theories
explaining how water accumulated on Earth: Slide 4 The Origins of
Water 2.Comet Theory: all of the Earths water comes from comets
that collided with the Earth. Small snow comets (weighing between
20 40 tons) collided with the Earth about 4 billion years ago.
Problem: No one has ever seen these snow comets. Slide 5 The
Origins of Oceans Label the major oceans on the map. What is the
worlds smallest ocean? What is the worlds largest ocean? Slide 6
The Origins of Oceans 200 million years ago Pangea: the original
continent when all 7 continents where joined together. Slide 7 The
Origins of Oceans Panathalassa: the one single ocean that surround
Pangea. It became the Pacific Ocean Sinus Borealis: A small body of
water in the northern coast of Pangea It became the Arctic Ocean
Slide 8 The Origins of Oceans 150 Million years ago A rift formed
between North America and Europe The rift is called the
Mid-Atlantic ridge and would later form the Atlantic Ocean. The
rift split Pangea into two smaller land masses; Laurasia and
Gondwana What land masses make up Laurasia? What land masses make
up Gondwana? Slide 9 The Origins of Oceans Which ocean is
increasing in size over time? Which ocean is decreasing in size
over time? Slide 10 Evidence for Plate Tectonics Alfred Wegner was
the first person to propose the idea of continental drift. He
called his theory plate tectonics Plate Tectonics: all continents
were together but broke apart and are still moving. Wegner had two
pieces of evidence supporting plate tectonics. 1.Fossils of the
same land animal were found on the eastern coast of South America
and the western coast of Africa. Slide 11 Evidence for Plate
Tectonics 2.Many of the continents look like they would fit
together like a jigsaw puzzle. Ex: South America and Africa Wagner
could not explain how the continents moved and was ignored by the
scientific community. Slide 12 Evidence for Plate Tectonics Henry
Hess discovered a huge mountain range in the middle of the Atlantic
Ocean, the Mid Atlantic Ridge. Hess said the that the ridge is
formed as magma rises up through deep valleys and forms new ocean
floor. Sea Floor Spreading: The new sea floor pushes the old sea
floor away from the ridge. Thanks to Hess and sea floor spreading
there is finally a force large enough for Wegners plate tectonics.
Slide 13 What Happens When the Plates Meet? Subduction: when two
tectonic plates collide and one sinks under the other. Subduction
causes trenches (deep depressions in the ocean floor) to form The
Earths crust is made of two different types of rock. 1.Basalt: a
very dense rock that forms the ocean floor 2.Granite: a less dense
rock that forms the continents Slide 14 What Happens When the
Plates Meet? What happens when oceanic crust (basalt) collides with
continental crust (granite). The oceanic crust will subduct and
melt under the continental crust because it is more dense forming a
trench. The melted basalt rises under the continental plate and
creates mountain ranges. Ex: Andes Mountains Slide 15 What Happens
When the Plates Meet? What happens when oceanic crust (basalt)
collides with oceanic crust (basalt)? The oceanic crust will
subduct and melt under the other forming a trench. The melted
basalt rises under the oceanic plate and creates island arcs. Ex:
Aleutian Islands Slide 16 Section 2: Ocean Provinces Two main
regions or provinces, of the ocean. 1.Continental Margin: the
shallowest parts of the ocean, consist of the area from the
continent to the deep sea floor. 2.Deep Sea Floor: the deepest part
of the ocean that consist only of basalt Slide 17 The Continental
Margin The continental margin has 3 main features: 1.Continental
Shelf: the shallowest, gently sloping section of the margin.
2.Continental Slope: the steepest sloping area of the continental
margin. 3.Continental Rise: gentle sloping area between the
continental slope and the sea floor. Slide 18 The Deep Ocean Basin
Abyssal Plain: the flat region that makes up most of the deep sea
floor. The abyssal plain is dotted with volcanoes in various stages
of life. 1.Seamout: young, pointed, active volcanoes that never
reach the surface. 2.Island: a seamount that grew enough to reach
the surface and form an island. 3.Guyot: a former island that been
eroded by waves below the waterline. Has a flat top. Slide 19
Section 3: The Movement of Water Currents: horizontal movement of
water across the ocean surface. All currents are caused by wind
Wind and the rotation of the Earth causes the water to move in a
swirling motion. Currents help regulate the temperature of the
Earth. Slide 20 The Movement of Water Upwelling: the upward
movement of water Warmer and less salty water rises to the surface.
Brings nutrients from the deep water to the shallow water at the
equator. Occurs at the equator. The Great Ocean Conveyer: water
moves between all 4 oceans and moves from between the surface and
the depths. Slide 21 The Movement of Water Downwelling: the
downward movement of water from the surface to the depths. Colder
and saltier surface water sinks and is replaced by warmer and less
salty water from the deep. Downwelling carriers oxygen to the
depths Occurs at the poles. Slide 22 Waves Like currents, most
waves are created by wind. What determines the size of the wave:
1.Stronger wind = bigger wave 2.The longer the distance and amount
of time the wind blows = bigger wave Parts of a Wave Crest: the
highest point Trough: the lowest point Height: distance between the
crest and the trough. Wave length: distance between two crests.
Slide 23 Waves What happens when waves get to shore? As the wave
approaches the shore it slows down because the bottom of the wave
rubs on the ocean floor. This causes the wavelength to decrease and
the wave height to increase. Eventually the wave height becomes too
high to be supported by the base and it topples over. Slide 24
Waves There are 2 basic types of waves: 1.Plunging Breakers: have a
curling crest that move over an air pocket creating a pipeline Only
occurs in surf zones with a steep slope The steep slope causes the
bottom of the wave to slow down faster that the top. The entire
wave leans toward the shore and the top falls over the wave. Slide
25 Waves 2.Spilling Breakers: waves that have a turbulent mixture
of air and water at the crest. Only occurs in a surf zone with a
gentle slope. The gentle slope on slows the wave down a small
amount. This causes the top to slide down on itself. True or False:
Plunging breakers are always larger than spilling breakers. Wave
Type has nothing to do with wave size. Slide 26 Special Waves Rogue
Waves: In the open ocean waves are constantly passing through each
other. Wave Destruction: when the crest of one wave combines with
the trough of another wave forming a much smaller wave. Wave
Construction: when the crest of one wave combines with the crest of
another wave forming a much larger wave. Rogue Waves: massive waves
formed by combining the crests of two waves. Slide 27 Special Waves
Tsunami: a wave caused by a large displacement of water. The causes
of a tsunami: A quick upward movement of the Earths crust (an
underwater earthquake). A avalanche, mudslide, or meteorite
plunging into the water. In open water, tsunamis are only about a
meter high and can move faster that the speed of sound. They can
only be observed once they reach the shore. Slide 28 Tides Tides:
the rise and fall of the water level resulting from the
gravitational pull of the sun and the moon. The gravity of the sun
and moon pulls on all parts of the Earth but only the water is able
to respond. Slide 29 Tides There are two types of tides: 1.Spring
tides: occurs when the sun and moon are aligned causing a large
difference between high and low tide. The gravitational pull of the
sun and moon work together Occurs during new moons and full moons
Slide 30 Tides 2.Neap tides: occurs when the Earth, sun and the
moon all form a right angle causing very little difference between
high and low tide. The gravitational pull of the sun and the moon
cancel each other out. Occurs during quarter or half moons. Looking
at the diagram, does the sun of the moon have a stronger
gravitational pull? Slide 31 Slide 32 Slide 33 Slide 34 Slide 35
Slide 36 Slide 37
