Name: _______________________
Period:_____
Marine Science Unit 1 Section 1:
Geology of the Oceans
A) How did the oceans form?
1) Earths surface first started accumulating water about 4
billion years ago, however there acre currently 2
leading theories that state how this could have
happened
a) Volcanic cycling theory – the theory which states
that all of earths water was released by
volcanic emissions
(I) When volcanoes on early earth erupted they put
lots of water vapor into the air
(II) Once earth cooled this water vapor condensed,
formed rain, and the deepest point of the earth
filled with water
b)
Comet theory - the theory which states that all of
earth’s water comes from earth colliding
with comets and other celestial bodies which
contain ice
(I) Some scientists sight data which suggests that
earth is constantly being bombarded by comet
like balls of ice that vaporize once
they enter earths atmosphere
(II) They believe that it is these alien ice
balls that first delivered all the water to
earth.
c) It is most not one or the other but both
The Volcanic cycling theory states that all of
earths water was released by volcanic
emissions
The 4 oceans:
The pacific ocean (largest and
deepest)
The Atlantic Ocean
The Indian Ocean
The Arctic ocean (smallest and
shallowest)
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B) The origins of the oceans and seas
1) 200 million years ago
a) Pangea – the original continent on earth
which consisted of all the continents
joined together
b) Panathalassa- the one singe ocean which
surrounded pangea and the planet. This was
the ancestor of the pacific ocean
c) Sinus Borealis – an indentation in the
northern coast of pangea that would become
the artic ocean
Earth 200 million years ago
2) 180 million years ago
a) 180 million years ago a rift started to form between north America and Europe which were joined
together.
(I) This rift split Pangea into two smaller contents, Laurasia and Gondwana
(II) The rift was called the mid Atlantic
ridge and would eventually from the
Atlantic ocean
(i) Laurasia- prehistoric super
continent that was composed of
north America, Europe, and Asia
(ii) Gondwana- prehistoric super
continent that was composed of
South America, Africa, Antarctica,
India, and Australia
3) 150 million years ago
a) A new rift forms in Gondwana splitting up
b) Africa and Antarctica.
c) This rift would form the Indian
Earth 180 million years ago
ocean
4) Today
a) The Atlantic ocean is still growing while the
Panathalassa (the pacific ocean) is still
shrinking
b) The rift that split Gondwana and formed the
Indian ocean extended to create the red
sea which is actually a young ocean
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Earth 150 million years ago
C) Alfred Wegner and plate tectonics
1) Alfred Wegener – a German geophysics who first formerly proposed the idea of continental drift
a) Alfred Wegener compiled multiple peaces of evidence which suggested that the earth was once
together in one super continent called pangea (Latin for all land)
First peace of Wegner’s evidence:
Fossil evidence shows many continuous lines of
fossils that seem to cross oceans
Second peace of Wagner’s evidence:
Manny continents like Africa and south
America seem to fit into each other like a
jigsaw puzzle
2) Wegner called his theory Plate Tectonics
a) Plate tectonics – the theory that the continents where once together as one unified land mass
but they have broken apart and are still moving
b) The problem with Wagner’s theory was that he could not provide evidence for a force strong enough
to move continents, and so he was largely ignored by the scientific community
D) Henry Hess and Sea Floor Spreading
1) In World war II, Henry Hess, a US Navy captain in world war II mapped the Atlantic sea floor using a
depth recorder looking for German subs
2) Hess discovered a huge mountain range in the middle of the ocean with a deep valley between it. He
called the mountain range the Mid Atlantic Ridge
a) Mid Atlantic Ridge – area of large mountains and deep valleys in the middle of all major oceans
(I) Hess took this discovery and published a paper in 1960 saying that the ridge is formed as
magma rises up through these deep valleys and forms new ocean floor
(II) This constant creation of new ocean floor forces the two oceanic plates that meet at the ridge to
move apart or spread
(III) Hess called this idea Sea floor spreading
(i) Sea floor spreading – Henry Hess’ Idea that the old sea floor moves away
from the ridge in order to create room for new sea floor
(ii) Thanks to Hess’ idea of sea floor spreading there was finally a force large enough to support
Wegner’s idea of plait tectonics
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E) Evidence for sea floor spreading
1) In the past 60 years Scientists have studied ocean floor near the ridge
1) These studies have found that bands of rock
closest to the ridge had large quantities of
iron that gives that rock unique
magnetic properties
a) Depending on when the bands of rock
hardened the iron particles point north or
south
b) Scientists use the direction the iron
particles are pointing to tell the
difference between newer rock
formed near the ridge and older
rock
c) Because over time scientists have observed
older bands moving away from the ride and
newer bands of rock forming closer to the
ridge they concluded that the sea floor is
spreading
Scientists use the direction the iron particles
are pointing in ocean rock to tell the
difference between newer rock formed near
the ridge and older rock
B) What happens when plates meet
1) The earths crust is mostly made out of two main types of rock, oceanic basalt, and continental granite
a) Basalt – the dense rock witch rises up through the ocean ridges and makes the ocean
floor
b) Granite – the less dense rock that composes most of the continents
(I) Because ocean basalt is more dense than continental granite, when these two rocks meet at plate
boundaries, the ocean plait usually sinks under the continental plate and melts
Ocean basalt is denser than continental granite, so when these two rocks meet the ocean basalt usually sinks
under the continental granite. This process of sinking is called Subduction
(II) Subduction – the process of one tectonic plate sinking under the other and melting
(i) Because Subduction involves the melting away of one plate it creates room for new
ocean floor to form at the ridge
(ii) Subduction causes trenches to form on the ocean floor
 Trench – a deep depression in the ocean floor caused by one plate sinking under another
as they meet
 The Marianas Trench in the pacific ocean is the deepest trench in the world as
well as the deepest point in all earths oceans
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When ocean basalt meets continental granite, the basalt subducts under the granite and a trench is created. As the
basalt sinks it melts and creates room for new floor to form at the ridge
C) The importance of ocean trenches
1) Manny different land formations are formed as a result of an oceanic trench
2) What type of land formations form depends on what types of rock meet
When Basalt meets Continental rock:
When Basalt meets Basalt:
1) When oceanic basalt meets continental granite
1) When oceanic basalt meets oceanic basalt, one
the more dense basalt subducts under
plate subducts under another creating a
the less dense granite creating a trench
trench, and starts to melt
and melts.
2) This hot melted basalt rises under the other
2) This hot melted basalt rises under the
oceanic plate and creates large volcanic
continental plate and create mountain
islands arks like the Aleutian islands
ranges like the Andes
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Marine Science Unit 1 Section 2:
Ocean Provinces
A) Two main regions of the ocean
1) The ocean floor is divided into two main regions or provinces, the relatively shallow
continental margin and the deep ocean basin
2) Because plate tectonics creates all the features in these regions the same main geological features mark
each region
a) The continental margin – the shallowest parts of the ocean that consist of the area between the
continent and the deep sea floor
(I) The continental margin has 3 main features, the Continental shelf, the Continental slope, and the
Continental rise.
b) The deep ocean basin– the deepest parts of the ocean that consist only of oceanic basalt
(I) The main feature on the deep ocean floor is the abyssal plain, however there are occasional
mountains called seamounts and guyots
(II) The deep ocean basin comprises about 30% of the surface of earth
The ocean floor is divided into two main regions, the relatively shallow continental margin and the deep ocean basin
B) Features of the Continental Margin
1) Continental shelf – The shallow gently sloping section of the continental margin that extends
from the shoreline to the steep sloping
continental slope
a) The continental shelf make up 8% of the
oceans floor and is the area with
the most biologically rich
part of the ocean
2) Continental slope – steepest sloping area
between the continental margin
3) Continental rise – a more gentle sloping area
at the base of the continental slope
C) Features of the deep ocean basin
1) Most of the deep sea floor lies at a depth of
about 13000 ft under water
2) the majority of the deep sea floor is flat and is
called the abyssal plain
a) The abyssal plain – the flat
region of the deep sea floor
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The continental shelf is divided into three main zones
based on depth and how steep the downward slope is
into the water, the continental self, the continental
slope, and the continental rise.
b) the abyssal plan is dotted with submarine volcanoes that are in various stages
of life:
(I) Seamount – pointed mountains on the abyssal plains formed from an active
underwater volcano
(i) sea mounts are relatively new features on the abyssal plain, and usually form near
ridges
(II) Volcanic island – a former volcanic seamount that has built on itself long enough to
breach the surface of the ocean and formed an island
(III) Guyot (Tablemount)- flat toped mountains on the abyssal plain formed from a volcanic island
that was once active but went extinct and eroded away above the water line
(i) The guyots are older features of the abyssal plain usually found farther away from the ridge
The majority of the sea floor is flat and featureless (the
abyssal plain). However The abyssal plain is dotted with
underwater volcanoes called seamounts. When these
volcanoes breach the surface of the water they form volcanic
islands. Once the volcano goes extinct the portion of the
island above water erodes away and a flat toped underwater
mountain is left called a guyot or table mount
D) What forms seamounts, volcanic islands and guyots
1) Hot Spot – An extraordinarily hot
stationary spot of magma under the
earths crust
a) As oceanic plates move over these spots the
extremely hot magma melts through
plate and crates a seamount, and could
build on itself to form a volcanic
island
b) After millions of years a chain of volcanic
islands forms in the middle of a plate
instead of at its edge where they usually are
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the
(I) Hawaii is an example of a series of volcanic islands that can form from one of these hot spots
c) When the plate the volcano is on moves away from the hot spot the island will stop building
on itself and begin to erode away
d) If the plate was only over the hot spot long enough to create a sea mount then the seamount will
remain on the abyssal plain
e) If the Hot spot created an island then eventually the plate will move causing the volcanic island to
stop erupting and begin to erode away creating a gyote
Marine Science Unit 1 Section 3:
The movement of ocean water
A) The two directional movement of ocean water
1) Ocean water moves in two main directions in the ocean, horizontally across the
surface of the water, and vertically from the depths of water into the shallows
B) Currents move water horizontally
1) Current – the name given to the
horizontal movement of water
across the oceans surface
a) All currents are driven by wind blowing
across the ocean
(I) As wind pushes water, the current
moves away from the direction of
the wind at an angle of 45o, this
creates a swirling motion
b) Currents in the ocean act mainly to
regulate the oceans
temperature, moving warm water
from the equator to the poles and moving cool water from the pools to the equator
C) The great ocean conveyer (Vertical circulation of water)
1) The great ocean conveyer – refers to the vertical circulation of water over the plaint.
This circulation delivers oxygen rich water to the depts. And nutrient rich water to the
shallows
a) Upwelling – the upward movement of water from the deep water to shallow water
(I) Upwelling results from because warmer less salty water in the deep rising because it is less dense
(II) Upwelling is responsible for delivering
nutrient rich water from the deep into
the shallows at the equator
b) Downwelling – the downward movement of
water from the surface to the depths
(I) Downwelling results mostly from colder more
salty surface waters sinking because it is more
dense
(II) Downwelling delivers oxygen rich water
to the depths at the pole
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D) Anatomy of a wave
1) Although waves are constantly moving they
have defined measurable features
a) Crest – the highest part of the wave
b) Trough – the lowest part of the wave
c) Wave height– the vertical distance between
crest and trough
d) Wave length – The distance between two
wave crests
E) How to make a wave
1) Most waves seen in the ocean are created by wind
2) The size of a wave depends on two things:
a) The stronger the wind the bigger the wave
b) The longer distance and period of time the wave blows over the bigger the w
F) What happens when ocean waves get to shore
1) Surf zone – the border between the ocean and shore where wave swells release there energy in the form
of breakers
2) There are 4 steps to how a wave breaks:
a) As the wave enters the surf zone the bottom of the wave begins to rub against the bottom
of the ocean
b) The more the bottom rubs, the more the wave slows down
c) As the wave begins to slow its starts to squish its sides together and the wave height
becomes larger as the wave length becomes shorter
d) Eventually the wave height becomes too high to be supported by the base and the
wave topples over
As a wave enters into the surf zone it begins to slow down. As the wave slows, the height of the wave builds
and the length of the wave shortens. Finally the wave becomes unstable and topples over on itself
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G) Wave types
1) What type of wave breaks depends on the characteristics of the shore bottom
2) There are two basic types of waves, plunging breakers and spilling breakers
Plunging breakers form on steep sloping surf zones:
Spilling breakers form on gentle sloping surf zones:
Plunging breakers – waves the have a
Spilling breakers – waves that have a
curling crest that move over a air pocket
turbulent mixture of air and water at the
or “pipe line”
crest
a) The steep sloping surf zone causes the
a) the gentle sloping surf zone only
bottom of the wave to slow down a
slows the wave a small amount
b) this type of slowing causes the top of the
lot faster than the top.
wave to spill over on itself
b) This type of slowing causes the whole
c) Spilling breakers don’t have to be small in
wave to lean towards the shore
fact:
and the top to fall over on the wave
c) Plunging breakers don’t have to be large, in
WAVE SIZE HAS NOTHING TO DO
fact:
WAVE SIZE HAS NOTHING TO DO
WITH WAVE TYPE
WITH WAVE TYPE
1 min in Endish start
D) Rogue waves
1) In the open ocean waves are constantly passing through each other
a) When waves pass through each other they can either combine their energy to briefly make a
larger wave or impede there energy and briefly make a smaller wave
(I) Wave construction – when two waves meet crest aligning with crest there heights
add to make a wave that is much higher
(i) 1:23 waves will encounter wave construction and be twice the average height
(ii) 1:300,000 will be 4 times the height
(iii)the chance of a truly monstrous wave is about 1 in a billon but it does happen
b) Rogue wave – massive weaves that can reach more than 100 ft higher in height than the surrounding
surf resulting from constructive interference in the ocean
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When waves pass through each other sometimes there crests perfectly
align and the result is a wave that is briefly much higher. Rogue waves
can result from multiple waves randomly coming together in this way
Rogue wave movie
E) Tsunamis
1) Tsunami – a large wave created by tectonic activity within the earth
a) There are a few causes of tsunamis:
(I) The quick upward movement of the earths crust in a earthquake displacing water on
the oceans surface can cause a tsunami
(i) This is the most common cause of tsunami however this produce the smallest waves
(II) Avalanches, mudslides, and Meteorites plunging into water canm also
cause tsunamis
(i) The latter two are much less common but have been responsible for the production of
the largest waves to have ever occurred in the ocean
b) In open water the height of a tsunami is only about a meter or so but it can be moving faster
than the speed of sound. For this reason tsunamis are only observable once they reach the
shore
deep impact
tsunami 2
F) How the sun and moon create the tides
1) Tides – the rise and fall of water level on earth resulting from the gravitational pull of the moon and sun
on the earth
2) The moon and suns gravity pull on all parts of the earth
a) The moon pulls more than the sun because it is closer
3) Because land cant go anywhere, only the earths water responds to the gravitational
pull of the moon and the sun
a) Tidal bulge – a large swell of water that results from the gravitational pull by the sun
and moon and earth.
(I) The first tidal bulge forms as water is pulled towards the moon from the sides of the earth
(II) The second tidal bulge forms because the water from the sides of the earth cant all fit on
the side of facing the moon, so some of it drains to the exact opposite side
(III) These two tidal bulges caused by the moon create the high tide and low tide points on earth
b) High tide is always directly below and opposite where the moon is around earth
c) Low tide is always on the side of earth the moon is not
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Earth
Moon
G) Types of Tides
1) Spring tides – when the sun earth and moon align (full moon or new moon) causing a large
difference between high and low tide
a) The pull of the sun and moon work together in spring tides
b) Spring tides result from New and full moons
2) Neap tides – when the sun earth and moon form right angles to each other (half moon) causing very
little difference between high and low tides
a) The pull of the sun and moon cancel each other out in neap tides
b) Neap tides result from Quarter or half moons
Steps to determine what tide is where on earth:
1. First determine High and Low tide:
a. High is directly below and opposite the moon
b. Low tide is always to the right and left of the moon
2. Second determine Spring or Neap tide:
a. Spring tide occurs when the earth sun and moon align (full and new moon)
b. Neap occurs when the sun earth and moon form a right angle (quarter moons)
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