Podcast
Questions and Answers
Which type of plate boundary is most closely associated with the formation of new ocean floor?
Which type of plate boundary is most closely associated with the formation of new ocean floor?
- Convergent
- Transform
- Divergent (correct)
- None of the above
Which of the following statements about Earth's magnetic field is most accurate?
Which of the following statements about Earth's magnetic field is most accurate?
- It remains constant over time.
- It cannot be measured.
- It switches polarity at irregular time intervals. (correct)
- It is not affected by tectonic activities.
How often does the Earth's magnetic field switch polarity?
How often does the Earth's magnetic field switch polarity?
Every 100,000 to several million years.
How are normal polarity and reverse polarity of Earth's magnetic field different?
How are normal polarity and reverse polarity of Earth's magnetic field different?
In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?
In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?
Where would you expect to see alternating bands of rock with different magnetic polarities?
Where would you expect to see alternating bands of rock with different magnetic polarities?
Where do mantle plumes originate?
Where do mantle plumes originate?
Why do hotspots result in chains of volcanoes instead of a single volcanic peak?
Why do hotspots result in chains of volcanoes instead of a single volcanic peak?
Which geographic example below was created by a hotspot?
Which geographic example below was created by a hotspot?
What happens when an oceanic plate converges with a continental plate?
What happens when an oceanic plate converges with a continental plate?
What happens when an oceanic plate meets another oceanic plate?
What happens when an oceanic plate meets another oceanic plate?
What happens when a continental plate meets another continental plate?
What happens when a continental plate meets another continental plate?
Which of the following features are found at an oceanic-continental convergent plate boundary?
Which of the following features are found at an oceanic-continental convergent plate boundary?
Which geographic examples result from ocean-ocean convergence?
Which geographic examples result from ocean-ocean convergence?
Transform boundaries are classified under what type of fault?
Transform boundaries are classified under what type of fault?
What role do transform boundaries play?
What role do transform boundaries play?
Do fracture zones near transform boundaries play a role in plate motion?
Do fracture zones near transform boundaries play a role in plate motion?
What is the relationship between transform boundaries and mid-ocean ridges?
What is the relationship between transform boundaries and mid-ocean ridges?
What is the relationship between the crust and the lithosphere?
What is the relationship between the crust and the lithosphere?
Complete this statement: Divergence is to moving away as convergence is to _______.
Complete this statement: Divergence is to moving away as convergence is to _______.
Plates move apart at __________ boundaries, move together at __________ boundaries, and move side by side at __________ boundaries.
Plates move apart at __________ boundaries, move together at __________ boundaries, and move side by side at __________ boundaries.
Which geologic features are associated with divergent boundaries?
Which geologic features are associated with divergent boundaries?
Which geologic features are associated with convergent boundaries?
Which geologic features are associated with convergent boundaries?
Where is the youngest ocean floor found?
Where is the youngest ocean floor found?
What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?
What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?
What is a volcanic arc?
What is a volcanic arc?
Which of the following mountain ranges are examples of continental arcs?
Which of the following mountain ranges are examples of continental arcs?
What did Pangaea (All Earth) split into 200 MYA?
What did Pangaea (All Earth) split into 200 MYA?
What is evidence for continental drift?
What is evidence for continental drift?
What are supporting evidences for plate tectonics?
What are supporting evidences for plate tectonics?
What are the components that liquid iron in the outer core conducts?
What are the components that liquid iron in the outer core conducts?
When flow reverses, polarity of magnetic field __________.
When flow reverses, polarity of magnetic field __________.
What is paleomagnetism?
What is paleomagnetism?
What are magnetic stripes?
What are magnetic stripes?
What does plate movements tracked by hotspots indicate?
What does plate movements tracked by hotspots indicate?
Where else are plumes found besides mid-ocean areas?
Where else are plumes found besides mid-ocean areas?
Study Notes
Plate Boundaries and Ocean Formation
- Divergent Boundaries: Associated with the formation of new ocean floor as plates move apart.
- Convergent Boundaries: Oceanic plates subduct beneath continental plates, forming trenches and volcanoes.
- Transform Boundaries: Plates slide horizontally past one another, creating strike-slip faults.
Earth's Magnetic Field
- Polarity switches occur at irregular intervals, every 100,000 to several million years.
- Normal polarity indicates a compass points to the North Pole; reverse polarity points to the South Pole.
- Oceanic rocks record changes in magnetic polarity, revealing a history of Earth’s magnetic field.
Geological Features
- Mid-Ocean Ridge: Long, underwater mountain ranges with alternating bands of rock displaying different magnetic polarities.
- Ocean Trenches: Formed at oceanic-continental and oceanic-oceanic convergent boundaries, indicating subduction zones.
Volcano Formation
- Hotspots: Chains of volcanoes form as tectonic plates move over stationary mantle plumes. Example: The Hawaiian Islands.
- Volcanic Arcs: Rows of volcanoes develop on overriding plates in subduction zones, exemplified by the Andes and Cascades mountains.
Continental Drift Evidence
- Continental coastlines, such as South America and Africa, fit together like puzzle pieces.
- Similar fossils across separated continents support the theory of continental drift.
- Glacial deposits align in the Northern Hemisphere evidencing past connections.
Plate Movements and Rates
- Tectonic plates move at a rate of approximately 5 cm per year, driven by mantle convection.
- Divergence creates new oceanic crust, while convergence leads to subduction and recycling of crust.
Rock and Crust Characteristics
- Youngest ocean floor is found along mid-ocean ridges, indicating ongoing formation.
- Ocean crust formed at divergent margins is dense and subducts when colliding with continental crust.
Supporting Evidence for Plate Tectonics
- Earthquake locations primarily clustered along plate boundaries, known as the "Ring of Fire".
- Age differences in seafloor and continental geology support tectonic activity.
- Paleomagnetism reflects historical changes in Earth’s magnetic field recorded in rocks.
Transform Faults
- Transform faults connect segments of mid-ocean ridges and exhibit a discontinuous pattern due to perpendicular fracture zones.
- The San Andreas Fault is a notable continental transform fault, exhibiting significant tectonic activity.
Additional Notes
- Liquid outer core is responsible for conducting electricity and convective flow, influencing Earth’s magnetic field.
- Magnetic stripes in ocean crust provide evidence of seafloor spreading and historical plate movements.
- Hotspot volcanism indicates the presence of stationary plumes of hot mantle material rising to create island chains.
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Description
Test your knowledge on plate tectonics and the ocean floor with this quiz based on Chapter 2 of Oceanography. Explore concepts such as divergent boundaries and the Earth's magnetic field behavior. Perfect for students looking to master oceanography fundamentals.
