Marine Science – Week 4
The geography and geology of the oceans
Name ____________________________
Theory of Continental Drift
Evidence for Continental Drift
1.
2.
3.
4.
Problem with Continental Drift
New Evidence
1. SONAR
Topographic map -
2. Seismic Activity
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3. Paleomagnetism
4. Radioactive dating of rocks
5. Satellite measurement
Plate Tectonics
Mechanism of plate tectonics
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Giant Undersea Volcano Found Off Iceland
Richard A. Lovett for National Geographic News - April 22, 2008
A giant and unusual underwater volcano lies just offshore of Iceland
on the Reykjanes Ridge, volcanologists have announced. The
Reykjanes formation is a section of the Mid-Atlantic Ridge, which
bisects the Atlantic Ocean where the North American and Eurasian
tectonic plates are pulling apart.
As magma wells up from the crack between the plates, it cools to
form ridges. But it doesn't generally form giant volcanoes, said
Ármann Höskuldsson, a University of Iceland volcanologist. That's
because mid-ocean ridges are constantly pulling apart, making it
harder for large volcanoes to form without being ripped apart.
"We were doing a normal oceangoing mission, and we found a big edifice" about 90 miles (150 kilometers)
south of Iceland, Höskuldsson said. The structure turned out to be an active volcano that rises about 3,300 feet
(1,000 meters) above the surrounding sections of the ridge, coming within 1,300 feet (400 meters) of the
surface. At its base the volcano is approximately 30 miles (50 kilometers) across.
The peak contains a depression known as a caldera that is 6 miles (10 kilometers) wide. That indicates that the
mountain is being fed by its own magma chamber, Höskuldsson said. "It's a higher magma production that
generates the volcano."
The underwater mountain resembles Krafla, an active aboveground volcano in northeastern Iceland that
contains a similar-size caldera, according to Höskuldsson. Krafla has erupted 29 times in recorded history,
most recently in 1984. Nobody knows when the undersea volcano might next erupt, but Höskuldsson thinks it is
only a matter of time. Still, the people of Iceland are in no danger, he said, because the volcano is so deep under
water. "We wouldn't expect much to happen on the surface."
Mostly, the find indicates how little is known about the seafloor, Höskuldsson said. "We are getting better
techniques, but the oceans of the world are huge." In the United States, for example, ocean scientists studying a
swarm of earthquakes off the Oregon coast are having a hard time pinning down the temblors' source, because
much of the seabed is poorly mapped. "There are all kinds of things on the seafloor we don't know about," said
Robert Embley, a National Oceanic and Atmospheric Administration scientist involved in the Oregon project.
Embley, who was not part of Höskuldsson's team, noted that satellite maps of Earth's gravitational field can be
used to map out undersea structures. But these maps don't provide the type of detail found by Höskuldsson.
"Even though … you can see big features, you can't really tell what they are. All you can say is its a big
feature," Embley said.
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Article Analysis Questions: “Giant Undersea Volcano Found Off Iceland”
1. Read, underline, and annotate the above article
2. Pick at least two words that you are not sure of the definition of and find the definitions. Write them below.
3. On what ocean-floor feature is this volcano located? __________________________________________
4. why don’t large volcanoes typically form on the mid-atlantic ridge?
5. Why has this volcano formed when large volcanoes are not typical on the ridge?
6. Why didn’t we know about this huge feature of the ocean before now?
7. Why do you think that so little is known about the ocean floor?
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Plate Tectonics in depth - The regions of the ocean floor
continental shelf
continental slope
abyssal plain
Regions of ocean floor here (with names and depths)
Hot Spot
Seamount
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Plate Tectonics in Depth - Plate Boundaries –
1. Divergent –
Divergent
Transform
2.Transform –
3.Convergent –
Convergent
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Blue Planet – Deep Seas
Video Analysis Questions
1. What is marine snow and why is it useful for organisms on the continental slope?
2. What is “Alvin” and why is it so important?
3. What are the challenges for living on the abyssal plain? What adaptations have organisms developed to
deal with these challenges (give at least 2)? (ex. deepwater corals, chimera, etc.)
4. What is meant by the term “living fossil”?
5. Where are hydrothermal vents found?
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6. Describe two of the organisms that live at hydrothermal vents.
7. Since there is no photosynthesis at the bottom of the ocean, how do organisms get their energy at
hydrothermal vents?
8. What is the difference between the water in an underwater lake and the water of the surrounding ocean?
9. How do organisms at underwater lakes get their energy?
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Living at the Bottom of the Ocean
Ecosystems of the ocean floor Energy
o Continental shelf
o Continental slope
o Abyssal plain
o Hydrothermal vents –

Chemosynthesis –

Food Chain
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Exploring the Ocean
Challenges –
Methods - Remote sensing –
-
Remotely operated vehicles –
-
Manned submersibles –
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Map Quiz  MONDAY!
To be successful on the map quiz, students should be able to plot the locations of the following features:
-
Atlantic Ocean
Pacific Ocean
Indian Ocean
Arctic Ocean
Southern Ocean
Gulf of Mexico
Mediterranean Sea
Caribbean Sea
Mississippi River
Amazon River
-
Peru-Chile Trench
Aleutian Trench
Japan Trench
Mariana Trench
-
Mid-Atlantic Ridge
East Pacific Rise
Additionally, students should be able to explain and show on a map the following things:
-
Where would you be likely to find earthquakes occurring?
Where would you find volcanoes?
Where would you find hydrothermal vents?
How can we tell where plate boundaries are located using the features above?
Which features above are associated with each type of plate boundary?
o Convergent
o Divergent
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