Download Mid-Ocean Ridge

Warm Up 2/4
 1. What is the biggest difference between an ROV and
an AUV?
 2. Name the ROV that explored the Titanic.
 3. Name the HOV that explored hydrothermal vents.
 4. Name the bathyscaphe that traveled to the Mariana
Trench
 5. What is one piece of information a scientist could
gather from an ocean corer?
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James Cameron Challenger Deep
43” diameter of internal cabin!!!
70 minute ascent!
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Ocean Geography
 Earth is 71% water
Is that water evenly distributed over the earth?
 Northern Hemisphere
 Southern Hemisphere
Nope!
61% ocean
80% ocean
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Water, water, every where,
Nor any drop to drink.
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Ocean Geography
 There are ____________ large ocean basins.
 1.
 2.
 3.
 4.
Are these oceans separate?
 “World Ocean” = term used by oceanographers
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SIZE
(in millions of
km2)
DEPTH
(feet … average)
TEMPS
PACIFIC
166.2
13,741
Depends on location
ATLANTIC
86.5
12,258
Depends on location
INDIAN
73.4
3,872
Hottest
ARCTIC
9.5
1,330
Coldest
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Ocean Diagrams in Notes
 Label, color code, cut and paste into notes
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Ocean Geography
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Ocean Geography
What’s the difference between an ocean and a
sea?
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Structure of the Earth
 Big Bang explosion 4.5 billion years ago
 Cosmic dust particles collide
 Condensed to a molten earth
 Denser particles flowed to center
D = mass
volume
Formation of Earth
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Figure 2.03
Layers of the earth cake
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Earth’s Layers Model
 Materials:
 Earth’s Layers handout
 Scissors
 Colored pencils
 Glue sticks
 textbook
 Procedure:
 Fill in blocks of 4 main
layers of earth on lower
right side
 Cut and paste blocks
next to corresponding
wedge
 Cut and label portions
of earth’s interior (terms
on left side)
 Use textbook as guides
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Earth’s Layers Model
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Layers of the Earth
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Layers of the Earth
 Core
 Inner Core – solid
 Outer Core – liquid
 Mantle
 Thought to be solid, but so hot that it flows like lava
 Swirls and mixes like boiling soup = convection
currents
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Layers of the Earth
 Mantle (continued)
 Asthenosphere


Portion of upper mantle
Location of convection
 Lithosphere
 Upper mantle into
the crust
 Where plates
located
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mantle convection
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Layers of the Earth
 Crust
 Thin in comparison to core and mantle
Ex) Gravy skin
 Rigid skin on top of mantle
 Two kinds
Banana pudding


Continental
Oceanic
Crust and Mantle - Wiz
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Structure of the Earth
 OCEANIC CRUST
 Basalt
 5km “thin”
 “young”
 Dark in color
 Iron, magnesium
=DENSE
 CONTINENTAL CRUST
 Granite
 20-50km thick
 “old”
 Light in color
 Sodium, potassium,
calcium, aluminum
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Continental Drift Theory
 Alfred Wegener
 1912
 Supercontinent
Pangaea
What is up
with
these drifting
continents,
y’all?
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Continental
Drift Theory
Similarities in:
1. types of fossils
(Mesosaurus)
2. shape and fit of
continents and
rock formations;
3. age and structure
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Evidence of continental drift
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Wegener’s proposed ‘Pangaea Puzzle’
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I know the plates
are moving. I just
don’t know how to
prove it…
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Plate Tectonics Theory 1950s
 Entire surface of earth moves, not just continents
 Lithosphere crust and uppermost mantle
 Plates- broken up pieces that move over the more
“plastic” (fluid) asthenosphere
REVIEW:
What’s the asthenosphere famous for???
CONVECTION CURRENTS!!
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What crazy awesome
technology developed
during WW2 helped to
validate the Theory of
Plate Tectonics??????
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SONAR
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Mid-Ocean Ridge
 discovered by sonar after WWII
 chain of submarine volcanic mountains
 Largest geological feature on the earth.
 Displaced from side to side by transform faults
(cracks)
Mid-Atlantic Ridge
East Pacific Rise
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Mid-ocean ridges, trenches, and transform
faults
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Portion
of the
midAtlantic
ridge in
Iceland
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Sea Floor Spreading (cont’d)
 Sonar also found trenches, mostly in the Pacific
 Tons of geological activity along mid ocean ridges.
 Earthquakes- near ridges
 Volcanic activity- near trenches
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 http://www.geosociety.org/educate/LessonPlans/SeaFl
oorSpreading.pdf
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Distribution of earthquakes and volcanoes
associated with plate boundaries
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Significance of Mid-ocean ridges
 Geologic ages- rocks near the ridge are “young”
compared to rocks far from the ridge
 Very little sediment near the ridge- and an increase in
sediment further from the ridge
 Magnetic anomaly bands
 Bands of rock on seafloor parallel to mid-ocean ridges
 Alternate between normal and reversed magnetization
 Mirror images on opposite sides of ridge
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Warm up 9/10
 Answer the following in complete sentences:
 In what state of matter does the inner core exist?
 What ocean has the greatest average depth?
 What hemisphere contains the greatest percentage of
ocean water?
 What term from yesterday’s earth picture does this
diagram represent?
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Warm up 9/11
1. Identify and describe
two differences in
characteristics of rock
near a mid-ocean ridge
as opposed to further
from the ridge.
2. Describe two of the
three pieces of evidence
that supported
Wegener’s Continental
Drift Theory.
3. What do the black and
white stripes on the
diagram below
represent?
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Agenda 9/11
 Finish seafloor spreading lab
 Resume notes
 Tsunami videos, article, questions
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Magnetic anomaly bands
prove seafloor not created
all at once but cooled from
molten material at
different times in geologic
history
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Creation of the Sea Floor
 Pieces of oceanic crust
separating at mid-ocean
ridges create cracks
called rifts
 Rifts release pressure
(remove cap from soda
bottle)
 Allow molten material
(bottled up) to reach
earth’s surface, cool,
solidify and form new
crust
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Creation of the Sea Floor
 Seafloor spreading = process by which the sea floor
moves away from the mid-ocean ridge to create new
sea floor
 Occurs at a divergent boundary (moving away)
Bill Nye Seafloor
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 MID-OCEAN RIDGE
 Seafloor spreading
 Divergent
 (plates separate, magma
bubbles up)
 TRENCH
 Subduction
 Convergent
 (plates move together,
form trench)
 Earthquakes = tsunamis
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Seafloor Spreading and Plate
Tectonics…
 REVIEW: Plates (in lithosphere) float on swirling
convection of asthenosphere
 New oceanic lithosphere (plates) formed at mid-ocean
ridges
 If that plate also includes a slab of continental plate,
then continents move too
 As new is created, old is destroyed. WHY?
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Seafloor Spreading and Plate
Tectonics…
 Lithosphere destroyed at trenches
 Formed when 2 plates collide and 1 dips below the other
and sinks into mantle
 https://www.youtube.com/watch?v=ryrXAGY1dmE
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Seafloor Spreading and Plate
Tectonics…
 Subduction = downward movement of plates
 Trenches are AKA “subduction zones” because this is
where subduction occurs!
 Convergent boundaries (moving together)
 Island arcs = volcanic island chains associated with
trenches
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Subduction of oceanic and continental plates
Subduction of two continental plates
Why will the
oceanic plate
sink under
the
continental
plate every
time?????
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Earth’s major lithospheric plates
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Tsunamis
 series of great sea waves caused by an underwater
earthquake, landslide, or volcanic eruption.
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Tsunamis
 Indonesian - History
Channel
 Japanese Tsunami 2011
 Banda Aceh Tsunami
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Warm up 9/12
Ridges and Trenches!!
1. In a complete sentence, compare and contrast ridges
and trenches by the plate boundary at which they
occur
2. Name the 2 major ridges of the Pacific and Atlantic
Oceans
3. At which geologic feature is seafloor created?
4. At which trench is seafloor destroyed?
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Agenda 9/12
 Finish tsunami work  worth a test grade now
 Finish notes  12 slides (only 8 with words)
 Sketch, label, submit designs with group members
(3-4 in each)
After school tutoring
 FRIDAY = models, lab questions
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Tohoku Tsunami
Tsunami crashing 1:30 in
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Fukushima
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Geologic Records in Ocean
Sediments
 Studying sediments gives clues to the history of the
earth
 Two major types:

1. Lithogenous- derived from terrestrial rock that
has been eroded- most common is red clay
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Geologic Records in Ocean
Sediments
 2. Biogenous- made of skeletons and shells of marine
organisms
 Calcareous ooze- primarily CaCO3, calcium carbonate
 Siliceous ooze- primarily SiO2, or silica.
 These microfossils can give clues to ancient ocean
temperatures
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Geological Provinces
of the Ocean
 Seafloor divided into 2
main regions
 1. Continental margins =
submerged edges of
continents
 2. Deep-sea floor
Continental
margin
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Continental Margin
 Boundaries between continental and oceanic crusts
 Where thick sediment deposits
Up to 6 miles of
sediment deep!
 Made of 3 parts:
 1. Continental shelf- biologically rich, part of continent
that is underwater.

Ends at a ‘shelf break’ where shelf abruptly gets steeper
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Continental margin (cont’d)
 2. Continental slope- begins at shelf break and descends
to deep-sea floor
 3. Continental rise- made of thick layers of sediments
building up on sea floor at the base of the slope.
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The Continental Margin
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Deep Ocean Basins
Abyssal Plain
 Great plain on ocean floor - very flat
 Covers 50% of earth’s surface
 Can be interrupted by seamounts (underwater
mountains), or guyots (flat topped seamounts)
 Habitat of unusual marine organisms
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Warm up 9/13
The tsunamis in Indonesia and Japan in 2004 and 2011
were a result of earthquakes at what type of plate
boundary?
2. What geological feature occurs at this type of boundary?
3. Describe the components that make up biogenous
sediment. How are these different than components of
lithogenous sediment?
4. Which part of the continental margin is the steepest and
occurs after the shelf break?
1.
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Warm Up 9/16
 In a complete sentence,
describe the differences
between passive and
active margins.
 Would point A fall on a
passive margin? Why or
why not?
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Warm Up 9/16
 Label the features represented at points A,B,C, and D
A
D
 Which of the four features represented at A,B,C, and D
accounts for the majority of the sea floor (and thus, earth’s
surface)?
 What is the difference between a guyot and a seamount?
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Agenda 9/16
 Finish models
 Finish lab questions
 Get your grade from me
 Vocabulary homework
 Notes/Pictures/Video on Hydrothermal vents
 Possibly start new material
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After school Review
 Today 2:20pm
 Meet here, possibly move rooms
 Going through the test by concept
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How big is the blob fish??
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Continental Margins
 Two Types
 1. Active margins- occur at plate boundaries




Geologically very active- earthquakes and volcanoes
trenches found offshore, no rise
shelf is nearly non-existent, slope is very steep
often have steep rocky shorelines
 Ex- West coast of South America
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Two types of Continental Margins
(cont’d)
 2. Passive margin- edge of continental crust is within a
plate- no plate boundary nearby




Geologically ‘inactive’
flat coastal plains
wide continental shelves, more gradual slopes, thick rises
Ex- North Carolina!
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Oceanic and
continental crust
meet at plate
boundary =
ACTIVE
Oceanic and
continental
crust meet
within a plate
= PASSIVE
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Multibeam sonar image of the continental shelf
off the coast of Atlantic City, NJ
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Multibeam sonar image of the coast of California
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Degrees West
Longitude
70.0
70.2
70.4
70.6
70.8
71.0
71.2
71.4
71.6
71.8
72.0
72.2
72.4
72.6
72.8
73.0
Elevation (m)
1945
2327
1193
-800
-1661
-3463
-4888
-7132
-5430
-4526
-3985
-4117
-4105
-4293
-3582
-4022
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Figure 2.20
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Mid-ocean ridges and hydrothermal
vents
 Separation at mid-ocean ridges creates cracks
called rifts
 Seawater seeps in the cracks and is heated by rising
magma
 Hot water rises through the crust as hydrothermal vents
(deep sea hot springs)
 Nat Geo hydrothermal vents
Up to 600
degrees!!
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Figure 2.23
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Hydrothermal Vents
 Lava bursting forth, bringing with it hydrogen sulfide,
or H2S, which is poisonous to living things on earth!!!
 These living species not only
survive in it, but they thrive. And
they do it in total darkness!!!!
H2S skin rash
(mild contact)
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Hydrothermal vents
 Mineral rich water cools in the ocean and the minerals
are deposited, making tall chimneys called black or
white smokers
 Rich in unusual marine life!!!!!
Hydrothermal vent creatures
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Hydrothermal vents
So why are scientists so surprised to find life so deep in
the ocean?
What did they previously think organisms needed to
survive?
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Figure 2.24
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Figure 2.25
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Organisms of Hydrothermal Vent
Communities
Tube worms have no
mouth, eyes or
stomachs- they have
bacteria inside them
that produce their food.
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Yeti Crab!!!!!!!!!!!!
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Vent crabs are predators in hydrothermal
vent communities…
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But the top dog is the Vent Octopus
Many animals at this
depth lack color or
pattern. Why????
In the dark, there’s no
need to camouflage for
hunting or hiding!
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Seafloor geology and life.
 What is the connection between the geological
features of the seafloor and living things in the
ocean??
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35 multiple choice
10 fill-in blank (6 diagram)
2 short answers
Test Information
 Four layers of earth
 Plate boundaries
 Four major ocean basins
 Oceanic vs. continental
crusts
 Wegner, Continental Drift
Theory, Plate Tectonics
 Review from first two quizzes
[4 questions]
 Mid-ocean ridges [MidAtlantic, East Pacific Rise,
rifts]






[Convergent vs. divergent]
Processes [seafloor spreading
vs. subduction]
Geological features [midocean ridge vs. trench]
Tsunamis and cause
Sediments
Continental margin, abyssal
plain
Hydrothermal vents
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Diagram on Test
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