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Period:_____
Marine Science Unit 1 Section 1:
Formation of the Oceans
A) How did the oceans form?
1) Volcanic cycling theory –
2)
Comet theory –
3) Which is more or less likely?
The 4 oceans:
1.
(largest and deepest)
2.
3.
4.
(smallest and shalowest)
B) The origins of the oceans and seas
1) 200 million years ago:
Marine Science Unit 1: Geology of the Oceans
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a) Pangea –
b) Panathalassa-
c)
Sinus Borealis –
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
(i) Laurasia- north America, Europe, and Asia
(ii) Gondwana- prehistoric super continent that was composed of everything not in Laurasia
(iii)What was the rift Called?
(iv) What would the rift create?
3) 150 million years ago
a) A new rift forms in Gondwana splitting up Africa and Antarctica.
b) This rift would form the Indian ocean
4) Today
a) What ocean is getting larger?
b) What ocean is getting smaller?
c) What sea is going to become an ocean?
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)
b) Continental Drift / Plate tectonics –
c) Wegner had 2 pieces of evidence to support his theory:
d) First support:
e) Second support:
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f) The Problem with Plate tectonics
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 the Mid Atlantic Ridge
a) Mid Atlantic Ridge – area of large mountains and deep valleys in the middle of the Atlantic ocean
(I) The discovery of the ridge provided a mechanism to explain 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
A) 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 –
b) Granite –
(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
(II) Subduction – the process of one tectonic plate sinking under the other and melting
(i) Subduction causes trenches to form on the ocean floor
 Trench –



Ocean trenches form the deepest parts of the ocean
The Marianas Trench is the world’s deepest trench at 36,201 feet (6.8 miles) deepest
If Mount Everest, which is the tallest point on earth at 8,850 meters (5 and 1/2 miles)
were set in the Mariana Trench, there would still be 2,183 meters (1 and 1/3 miles) of
water left above it.
B) The importance of Subduction and ocean trenches
1) 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:
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When Basalt meets Basalt:
Marine Science Unit 1 Section 2:
Features of the Oceans
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
a) The continental margin –
(I) The continental margin has 3 main features,
(i) Continental shelf –
(ii) Continental slope –
(iii)Continental rise –
(II) The Ocean Basin–
(III) Features on the deep ocean basin:
b) The abyssal plain –
c) Seamounts –
d) Volcanic islands –
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e) Guyots (Tablemounts)f) Although seamounts may never rise high enough to break the surface of the water and become
islands, ALL volcanic islands will eventually become Guyotes
B) Hot spots
1) Hot Spot – An e hot stationary spot of magma under the earths crust
a) As oceanic plates move over these spots the extremely hot magma melts through the plate
and crates a series of seamounts, volcanic islands and Guyotes / Tablemounts
(I) Hawaii is an example of a series of volcanic islands that can form from one of these hot spots
b) Hot spots explain how seamounts, islands and guyotes can form without trenches and subduction
and
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
2) Current – the name given to the horizontal movement of water across the oceans surface
a) What creates Currents?
b) What do currents do for the ocean?
B) The great ocean conveyer (Vertical circulation of water)
1) The great ocean conveyer – refers to the vertical circulation of water over the plaint.
a) Upwelling – the upward movement of water from the deep water to shallow water
b) Downwelling – the downward movement of water from the surface to the depths
c) What creates currents?
d) What does Upwelling and downwelling do for the ocean?
e) When does upwelling and downwelling occur?
D) Anatomy of a wave
a) Wave Crest –
b) Wave Trough
c) Wave Height –
d) Wave Length Marine Science Unit 1: Geology of the Oceans
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E) How to make a wave
a) What creates a wave?
b) What three charicteristics does wind have to have to create Large waves?
F) Why/how do waves break?
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
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
What creates plunging Breakers?
WAVE SIZE HAS NOTHING TO DO
WITH WAVE TYPE
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What creates spilling breakers?
WAVE SIZE HAS NOTHING TO DO
WITH WAVE TYPE
1 min in Endish start
C) Rogue waves
a) 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
(i) 1:23 waves will encounter wave construction and be twice the average height
(ii) 1:1175 will be three times higher as a result of wave construction
(iii)1:300,000 will be 4 times the height
(iv) the chance of a truly monstrous wave is about 1 in a billon but it does happen
b) What creates Rouge Waves?
When waves pas 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
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D) Tsunamis
1) Tsunami – a large wave created by tectonic activity within the earth
a) Three causes of a tsunami:
(I)
(II)
(III)
deep impact tsunami 2
E) 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.
4) How tides form:
a) As the moon rotates around the earth 2 tidal bulges are created:
(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
F) How do to determine high tide and low tide?
1) High Tide3 and low Tide is determined only be the moons location around the earth.
a) High tide will always be directly under and opposite the moon
b) Low tide will always be on the sides of the earth that the moon is not
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
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Different tides
result from the
sun and moon
pulling in
different
directions on
earths water
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