Transcript 19.2 Features of the Ocean Floor Powerpoint Notes

19.2: Features of the Ocean Floor
Schedule
• Friday
– Turn in 19.2 reading guide
– Turn in progress reports (due Tuesday)
– Notes, project (Due Tuesday)
• Should have graph finished by end of class!
Bell Work 2/27/12 - minutes
1. Sketch and label the 3 parts of a
continental margin.
2. What is the circumference of Earth?
3. How long would it take to drive around at
60 mi/hr?
4. How long would it take to fly around at
550 mi/hr?
5. W5SAYWoS
Today you are going to…
turn in syllabus
look over all of So you can…
better appreciate the size/scale of Earth
identify the parts of the Earth system & how they
interact
convert from km to mi
You’ll know you’ve got it when you
can answer the questions on the reading guide
Quiz A
1. B
2. B
3. B
4. D
5. D
6. D
7. E
8. B
9. E
10. D
11. C
12. C
13. E
14. B
Quiz B
1. D
2. E
3. B
4. E
5. D
6. B
7. B
8. B
9. D
10. D
11. C
12. E
13. B
14. A
15. A
15. A
16. A
17. A
18. C
19. A
1. L
2. K
3. F
4. B
5. I
6. E
7. L
8. M
9. A
10. J
Quiz A
11. H
12. N
13. C
Quiz B
16. A
17. C
18. A
19. C
1. C
2. D
3. I
4. M
5. F
6. J
7. C
8. B
9. N
10. E
11. G
12. A
13. L
Bell Work 10/2/13 – 4 minutes
1.
2.
3.
4.
UNEXCUSED ABSENCES!! 
Which type of boundary is at the mid-ocean ridge?
What process is happening at the mid-ocean ridge?
What is the evidence?
Which type of boundary is at subduction zones?
What ocean floor feature is found at a subduction
zone?
Bell Work 9/30/13 – 4 minutes
1. What is the circumference of Earth?
2. How long would it take to drive around at
60 mi/hr?
3. How long would it take to fly around at
550 mi/hr?
4. Describe the bottom of the ocean.
5. W5SAYWoS
Monday
Schedule
Review Seasonal Seas Video Worksheet
progress reports (due next Monday)
Plate Tectonics Video
Tuesday
Collect 19.2 reading guide
Anyone not take ze quiz?
Finish video
Check 19.1 quiz
Wednesday
Notes on ocean basins
Ocean Profile Graph
Thursday
Notes on Ocean Life Zones
Video & Info on Azores Island
Ocean Profile Graph (due Friday)
Friday
Map Mystery Box?
Bell Work 10/7/13 – 4 minutes
1. What are the 3 parts of the continental
margin?
2. W5SAYWoS
Schedule
• Friday
– Notes, project
• Monday
– Notes, project (due Tuesday)
• Tuesday
– Finish notes Study guide/questions, review reading guide
• Wednesday
– Awesome video?
• Thursday
– Review?
• Friday
– Quiz
Features of the Ocean Floor
• 2 major areas
– Continental Margin
• The edge of the continent that’s underwater
– Deep-Ocean Basin
• oceanic crust
The Continental Margin
• Underwater part of the continental crust
• Consists of continental crust & thick
wedge of sediment
• 3 parts
1. Continental shelf
2. Continental slope
3. Continental rise
1. Continental Shelf
• Gently sloping part of a continent that
extends out to continental slope.
– up to 1280 km (800 mi) long!
– Rarely more than 200 m (____ft) deep
– Most ocean resources come from the
continental shelf
2. Continental Slope
“Steep” edge of continent
-
begins at the shelf edge where the
water depth increases rapidly.
-
about 20 km (_____ mi) wide
descends about 3.6 km (_____ mi)
Slope of _______
the actual edge of continent
-
3. Continental Rise
• a gradual slope of sediment beginning at
base of continental slope
Submarine Canyons
• Large underwater valleys cutting through the
continental shelf
• Caused by rivers as flowing water erodes edge of
continent
• Turbidity currents also create submarine canyons
– They’re underwater landslides, dense currents of sediment
– Caused by a buildup of sediment or an earthquake
Submarine Fan!
• Fan-shaped pile of sediment where a
submarine canyon meets the ocean floor
Active & Passive Margins
• Active continental margin – located at
plate boundaries
– Convergent boundary - oceanic plate
subducts beneath the continental plate.
Volcanoes occur on the edge of the
continents where this happens.
– Transform boundary – plates slide past one
another, cause earthquakes
– Deep ocean trenches are found at active
margins
Active & Passive Margins
• Passive continental margins – not located
at plate boundaries.
– No deep ocean trenches.
– Coastal plains are found along passive
margins.
Features of Ocean Floor
• 2 major areas
– Continental Margin
• The edge of the continent that’s underwater
– Deep-Ocean Basin
• oceanic crust
Abyssal
ABYSS
- the bottomless gulf, pit
- an immeasurably deep gulf or great space
Abyssal
- unfathomable
– of or relating to the great depths of the ocean
Abyssal Plain & Abyssal Hills
• Abyssal plain – vast flat areas of ocean basin
– flattest places on Earth! 1300 km
• (_____ mi) only change 3 m (_____ ft)
– Covered with fine sediment covering the ocean
floor (caused it to be flat, like snow)
– Most of the sediment here came from rivers, some
fell from above
• Abyssal Hills – rolling hills in the ocean, often
found near the oceanic ridge
Laurentian Abyss
• In the 2007 film Transformers, the body of Megatron is dropped into the
abyss.
• It is stated that the pressure and "sub-freezing" temperatures (presumably
meaning below the freezing point of pure water at 1 atmosphere of pressure)
at this depth would "crush and entomb" the evil alien robot.
• film doubly erroneously states that the abyss is, at 7 miles (11.3 km) below
sea level, the deepest point on Earth; the actual deepest point is
the Challenger Deep, a section of the Mariana Trench in the Pacific Ocean,
which has an estimated depth of slightly less than seven miles.
• 2009 film Transformers: Revenge of the Fallen, the remains are found at the
bottom of the Abyss and Megatron is reactivated. Decepticon Protoforms are
also seen climbing up a destroyed ship sinking into the Abyss waters.
• The film incorrectly states that the abyss is 9,300 fathoms deep, or about
55,800 feet (10.6 miles; 17.0 km) deep.
Laurentian Abyss
The Ocean Basin
Tectonic Plate Boundaries
• Convergent   move towards each other
– Collision
– Subduction
• Divergent   move away from each other
• Transform slide past each other
Deep-Sea Trenches
• long, narrow depressions that run parallel
to continental margins
• Form at edge subduction zones
– Earthquakes, volcanic mountain ranges, and
volcanic island arcs form near trenches
The Mariana Trench
• deepest part of the ocean, over 11 km
(almost ____ mi) deep
– Deepest part called “Challenger Deep”
• In western Pacific Ocean, south of Japan
• Deeper than Mt. Everest is tall!
• Jacques Piccard & Don Walsh went to bottom
in Trieste (TREE-est-a) on January 23, 1960!
– Took nearly 5 hours to get down!
– Window cracked on way down!
– 20 min there, 3:15 back
Bell Work!
• Take the following out:
– 19.1 Reading Guide
– 19.2 Reading Guide
Mid-Ocean Ridges
• Underwater mountain ranges that run along
floors of ocean. They form a chain over 50,000
km long!
• Rarely rise above sea level
– Iceland & Azores Islands are 2 of few places it’s
above sea level!
• They form at divergent plate boundaries where
the plates are moving apart (a process called
seafloor spreading)
• There is a rift valley in the middle where the
new seafloor is formed.
Azores Islands
• On Mid Ocean Ridge
– Formed via volcano
•
•
•
•
Lava tubes, hot springs, cook food in ground
Belong to Portugal.
Export cheese, wine, and Nelly!
Nelly Furtado is native to the Azores Islands!
Azores Islands
Hydrothermal Vents
Early clues
strangely warm water
metal-rich sediments near mid ocean ridge &
volcanically active areas
“missing heat”
Ophiolites – sea floor above sea level
Hydrothermal Vents
Discovered in 1977
• Water seeps into cracks in ocean floor,
becomes superheated & dissolves minerals,
shoots out of vents, minerals precipitate back
out
• 1st ones discovered near Galapagos Islands
The first black-smoker chimney ever
seen by humans— photographed at
21°N in 1979.
The chimney “smoke” really consists of
superheated (350°C or 662°F) fluids that are
filled with dark mineral particles.
• Precipitating minerals form “blackersmoker” chimneys that can grow very tall.
The tallest one found so far was a
structure on the Juan de Fuca Ridge,
which scientists called “Godzilla.” It
reached 16 stories high before it toppled
over.
Chemosynthesis
• Sulfate, which is abundant in seawater, is
converted into hydrogen sulfide as the
seawater circulates in the ocean crust.
• Bacteria and other microorganisms use
the hydrogen sulfide (H2S) in the
hydrothermal fluids to make food.
• Higher organisms feed on these bacteria.
• Entire ecosystem doesn’t need sunlight for
energy!
Tubeworms, white crabs, and a
pink fish gather at a Galápagos Rift
vent site
A purple octopus scavenges in
a clam-filled vent site
Hydrothermal Vents
Mineral encrusted mounds sticking out of
sediments, discovered by Deeptow
• On each of its dives, Alvin’s front basket and
cameras captured a remarkable variety of
animals that never had been seen before:
• unknown mussels, anemones, whelks, limpets,
featherduster worms, snails, lobsters, brittle
stars, and blind white crabs.
• One crustacean seemed to have teeth on the
end of eyestalks, which scientists speculated
were used to scrape food off rocks.
• giant white clams with blood-red flesh was
given the scientific namemagnifica.
• The delicate, orange, dandelion-looking creature
seen on the 1977 cruise turned out to be called
a siphonophore—a cousin of the Portuguese
man-of-war. Alvin technicians fashioned a
special “dandelion-catching” container, but the
siphonophore quickly disintegrated after it was
brought to the surface.
• Woods Hole biologist Holger Jannasch proved that these bacteria
used hydrogen sulfide from vent fluids to take the carbon from
carbon dioxide, a gas dissolved in seawater. They convert this
carbon into “organic” carbon, which they can use as food.
Plants do the same thing, using carbon dioxide from air and sunlight
as energy, in a process called photosynthesis. In the sunless
depths, microorganisms create organic carbon using chemicals for
their energy source, a process called chemosynthesis.
• At 21°N, scientists discovered black
smoker chimneys spewing scalding hot
fluids for the first time. They saw that
hydrothermal vents were also great
furnaces, where many of Earth’s great ore
deposits were made.
John B. Corliss cradles a specimen of a
giant clam retrieved on 1977
Galápagos Rift expedition.
• Vents are only active a few decades.
When vents stop, all organisms that can’t
find new vents die.
ANGUS took this photo of dead clams at
Clambake 2. The clams died because the
vent was no longer active.
Seamounts
• Submerged volcanic mountains taller than
1 km (____ mi)
• Form over hot spots
– Hot Spots Animation!
• Can form volcanic islands
– Hawaii is over a hot spot!
• Mauna Kea the tallest mountain!
– 10,203 km high (________ mi)
• Mt. Everest is the highest mountain.
– 8.8 km (________ mi) above sea level
• Island forming
Hawaiian Music to work to!
• http://www.youtube.com/watch?v=V1bFr2
SWP1I
Guyots
• flat topped underwater mountains
• form when:
– 1. volcanic islands sink
– 2. waves erode island, making it flat
– 3. island sinks below sea level
• Also called “tablemounts”
Coral Atolls
• Coral - marine invertebrates typically living in compact
colonies of many identical individual "polyps".
– Corals near surface eat plankton AND get food from algae
that lives inside them. Because algae needs sunlight to
make food, these corals need to be in the sunlit zone.
– The algae give the corals their awesome colors!
• ring-shaped coral island
• Forms when:
1. coral grows in the shallow area around volcanic island
2. volcanic island eventually sinks below sea level, leaving a
ring of coral
Formation of Atoll
• http://www.youtube.com/watch?v=vrD1O5
hex6Y
Corals & Coral Atolls
• Coral - marine invertebrates typically living in
compact colonies of many identical individual
"polyps".
• Coral Atoll - ring-shaped coral island
• Forms when:
1. coral grows in the shallow area around volcanic island
2. volcanic island eventually sinks below sea level,
leaving a ring of coral
Barrier Reefs
• Coral reef – limestone formation of corals
& coral skeletons
• Barrier Reef – coral reef that forms around
an island or a short distance from shore
Great Barrier Reef
• Off northwestern shore of Australia
• one of the seven wonders of the natural
world
• larger than the Great Wall of China
• the only living thing on Earth visible from
space.
 Draw this 
1.
2.
3.
4.
5.
6.
7.
8.
Abyssal plain
3/2/12
Continental Rise
Continental Shelf
Continental Slope
Guyot
Ocean ridge
Seamount
Deep ocean trench
D
E
A
B
C
F
G
H
STOP
Preguntas!
1. What are the flattest places on Earth?
How did they get so flat?
2. What is an atoll? How does it form?
Bell Work 3/6/12 – 3 minutes
•
1 fathom = 1.8 m
1 km = 1000 m 1 fathom = 6 ft
1. 500 fathoms = ? feet
2. 777 fathoms = ? feet
3. 500 fathoms = ? meters = ? kilometers
4. 777 fathoms = ? meters = ? kilometers
5. How many times bigger is 2500 than 500?
6. What are the flattest places on Earth & why are they so flat?
7. What kind of boundary is located at the mid oceanic ridge?
8. What process occurs at the mid oceanic ridge?
9. What are the deepest ocean features called?
10. Where are they located?
11. Why do submarines need sonar?
12. Draw a guyot. How does it form?
13. The mid oceanic ridge is on which type of boundary?
14. Calculate the depth in feet if the sonar time is 0.488 s.
15. Convert this to fathoms (1 fathom = 6 ft).
Bonus!
• Write your answer in the little blue subject
box. Include units?
• Kelsey is chillin in the Grand Canyon when
she wonders how far away a cliff face is.
She yells “I LOVE SCIENCE” and measures
the time it takes for her to hear the echo. If it
takes 2.75 s, how many miles away was the
cliff?
 Draw this 