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 Quiz B1. 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

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

Quiz A Quiz B15. A

16. A

17. A

18. C

19. A

1. L 11. H

2. K 12. N

3. F 13. C

4. B

5. I

6. E

7. L

8. M

9. A

10.J

16. A17. C18. A19. C1. C2. D3. I4. M5. F6. J7. C8. B9. N10.E11.G12.A13.L

Bell Work 10/2/13 – 4 minutes

UNEXCUSED ABSENCES!! 1. Which type of boundary is at the mid-ocean ridge?

2. What process is happening at the mid-ocean ridge? What is the evidence?

3. Which type of boundary is at subduction zones?

4. 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

ScheduleMondayReview Seasonal Seas Video Worksheet

progress reports (due next Monday)

Plate Tectonics Video

TuesdayCollect 19.2 reading guide

Anyone not take ze quiz?

Finish video

Check 19.1 quiz

WednesdayNotes on ocean basins

Ocean Profile Graph

ThursdayNotes on Ocean Life Zones

Video & Info on Azores Island

Ocean Profile Graph (due Friday)

FridayMap 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 parts1. 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

AbyssalABYSS

- 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 “blacker-smoker” 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=V1bFr2SWP1I

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=vrD1O5hex6Y

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. Abyssal plain 3/2/12

2. Continental Rise

3. Continental Shelf

4. Continental Slope

5. Guyot

6. Ocean ridge

7. Seamount

8. Deep ocean trench

BA

D

C

FEH

G

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).

16.Convert this distance to meters (1 m = 3.28 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