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Questions and Answers
Questions and Answers
Which of the following is the most accurate description of the relationship between the lithosphere and the asthenosphere?
Which of the following is the most accurate description of the relationship between the lithosphere and the asthenosphere?
- The lithosphere and asthenosphere are both part of the Earth's core.
- The lithosphere is composed of the same material as the asthenosphere but is more viscous.
- The lithosphere is divided into plates that float and move on the semi-molten asthenosphere. (correct)
- The asthenosphere is a rigid layer that sits atop the more flexible lithosphere.
Plate tectonics is a unifying theory in geology because it connects which of the following Earth processes?
Plate tectonics is a unifying theory in geology because it connects which of the following Earth processes?
- Ocean currents, atmospheric pressure, and the water cycle.
- Erosion, weathering, and the formation of sedimentary rocks.
- The rock cycle, carbon cycle, mountain formation, and the location of earthquakes and volcanoes. (correct)
- The Earth's magnetic field, solar winds, and the aurora borealis.
Which of the following plates is classified as a major plate based on its surface area?
Which of the following plates is classified as a major plate based on its surface area?
- Nazca Plate
- Caribbean Plate
- Philippine Plate
- Eurasian Plate (correct)
What is the primary driving force behind the movement of tectonic plates?
What is the primary driving force behind the movement of tectonic plates?
At a mid-ocean ridge, the force that contributes to the movement of lithospheric plates away from the ridge is primarily:
At a mid-ocean ridge, the force that contributes to the movement of lithospheric plates away from the ridge is primarily:
In a subduction zone, what is the main force that pulls the rest of the plate behind the descending slab?
In a subduction zone, what is the main force that pulls the rest of the plate behind the descending slab?
What role does friction play in the movement of lithospheric plates at subduction zones?
What role does friction play in the movement of lithospheric plates at subduction zones?
The theory of plate tectonics is based on the combination of which two pre-existing ideas?
The theory of plate tectonics is based on the combination of which two pre-existing ideas?
Which geological feature is least likely to be associated with a divergent plate boundary?
Which geological feature is least likely to be associated with a divergent plate boundary?
What is the primary mechanism driving the formation of new crustal material at divergent boundaries?
What is the primary mechanism driving the formation of new crustal material at divergent boundaries?
What is the key difference in the crustal interaction between a continent-continent convergent boundary and an ocean-continent convergent boundary?
What is the key difference in the crustal interaction between a continent-continent convergent boundary and an ocean-continent convergent boundary?
What distinguishes transform boundaries from both convergent and divergent boundaries?
What distinguishes transform boundaries from both convergent and divergent boundaries?
Which of the following geological features is a direct result of the collision between the Indian and Eurasian plates?
Which of the following geological features is a direct result of the collision between the Indian and Eurasian plates?
Why do plates at transform boundaries often move in fits and starts, rather than gliding smoothly?
Why do plates at transform boundaries often move in fits and starts, rather than gliding smoothly?
In a subduction zone where an oceanic plate meets a continental plate, which plate is more likely to be subducted and why?
In a subduction zone where an oceanic plate meets a continental plate, which plate is more likely to be subducted and why?
What is a back-arc basin, and what type of plate boundary is it associated with?
What is a back-arc basin, and what type of plate boundary is it associated with?
Which of the following observations initially supported Alfred Wegener's theory of continental drift?
Which of the following observations initially supported Alfred Wegener's theory of continental drift?
What key characteristic of magnetic anomalies on the seafloor supports the theory of seafloor spreading?
What key characteristic of magnetic anomalies on the seafloor supports the theory of seafloor spreading?
How did Harry Hess's concept of seafloor spreading refine the theory of continental drift?
How did Harry Hess's concept of seafloor spreading refine the theory of continental drift?
Which of the following best describes the process of subduction in the context of seafloor spreading?
Which of the following best describes the process of subduction in the context of seafloor spreading?
What is the significance of Glossopteris fossils being found on multiple continents in the Southern Hemisphere?
What is the significance of Glossopteris fossils being found on multiple continents in the Southern Hemisphere?
Which of the following is a direct consequence of seafloor spreading?
Which of the following is a direct consequence of seafloor spreading?
What role does mantle convection play in the theory of seafloor spreading?
What role does mantle convection play in the theory of seafloor spreading?
Laurasia and Gondwanaland are believed to have formed from the breakup of which supercontinent?
Laurasia and Gondwanaland are believed to have formed from the breakup of which supercontinent?
Questions and Answers
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Flashcards
Flashcards
Plate Tectonics
Plate Tectonics
Theory describing the movement of Earth's lithospheric plates.
Lithosphere
Lithosphere
The rigid outer layer of the Earth, divided into plates.
Asthenosphere
Asthenosphere
Hot, deformable layer beneath the lithosphere where plates float.
Tectonic Plates
Tectonic Plates
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Major Tectonic Plates
Major Tectonic Plates
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Mantle Convection
Mantle Convection
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Ridge Push
Ridge Push
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Slab Pull
Slab Pull
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Seafloor Spreading
Seafloor Spreading
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Continental Drift
Continental Drift
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Pangaea
Pangaea
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Laurasia
Laurasia
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Gondwanaland
Gondwanaland
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Convection
Convection
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Subduction Zones
Subduction Zones
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Magnetic Anomalies
Magnetic Anomalies
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Divergent Margin
Divergent Margin
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Transform Margin
Transform Margin
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Convergent Margin
Convergent Margin
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Island Arcs
Island Arcs
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Oceanic Trenches
Oceanic Trenches
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Continent-Continent Collision
Continent-Continent Collision
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Mid-Oceanic Ridges
Mid-Oceanic Ridges
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Flashcards
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Study Notes
Study Notes
- Plate tectonics is a theory describing the movements of Earth's plates, with the lithosphere divided into plates that float on the asthenosphere.
- These plates move in various directions, spreading, colliding, and grinding against each other.
- Plates are made up of stiff and rigid blocks of lithosphere.
- Plate tectonics helps explain how Earth works as a system, connecting the rock and carbon cycles, mountain formation, ore deposits, and the locations of continents, oceans, mountains, volcanoes, and earthquakes.
Plates
- The major plates consist of seven plates, all greater than 20 million km²: Pacific, North American, Eurasian, African, Antarctic, Indo-Australian, and South American.
- Minor plates range from 1 to 20 million km², and microplates are less than 1 million km².
Driving Forces of Plate Tectonics
- The driving force behind plate tectonics is convection in the mantle.
- Hot material rises from near the Earth's core, while colder mantle rock sinks.
- Convection drives plate tectonics through a combination of pushing and spreading at mid-ocean ridges and pulling and sinking at subduction zones.
Forces Moving the Lithosphere
- Ridge push occurs at mid-ocean ridges, where young lithosphere sits atop a topographic high, and gravity induces it to slide down, pushing against thicker lithosphere.
- Slab pull happens at subduction zones, where cold, dense slabs sink into the mantle and pull the rest of the lithosphere into the oceanic trench.
- Friction from viscous mantle rock borders the lithosphere and drags on the top, bottom, and leading edge of descending lithosphere in the subduction zone, as well as elsewhere at the base of the plate.
Continental Drift Theory
- Plate tectonics concept combines continental drift with seafloor spreading.
- Continental drift suggests continents move freely over the Earth's surface, changing their positions relative to one another.
Supporting Data
- In the early 1900s, Alfred Wegener noted similar late Paleozoic rocks and fossils in South America, Africa, India, Antarctica, and Australia.
- The plant Glossopteris is found in Pennsylvanian and Permian age rock across all 5 continents.
- Mesosaurus, a freshwater reptile, are found solely in Permian-age rocks in Brazil and South Africa.
- Lystrosaurus and Cynognathus fossil remains are found in Triassic-age rocks on all five continents.
Pangaea
- Wegener reassembled the continents into the supercontinet of Pangae.
- Pangaea separated into Laurasia, the northern supercontinent, and Gondwanaland, the southern supercontinent.
- Paleomagnetic evidence shows matched rock contacts and radioisotope ages between South America and Africa.
- Rocks in Brazil and Gabon are similar in type, structure, sequence, fossils, ages, and metamorphism.
Seafloor Spreading
- Harry Hess proposed seafloor movement.
- Hess theorized the the seafloor moves like a conveyer belt from the mid-oceanic ridge, down the ridge's flanks, across the basin, plunging beneath a continent or island arc (subduction).
- Seafloor spreading is driven by deep mantle convection where hot material rises and cold material sinks; hot material has lower density, and cold material has higher density.
Evidence of Plate Movement and Magnetic Anomalies
- Magnetometer surveys show magnetic anomalies arranged in bands parallel to the rift valley of mid-oceanic ridges.
- Alternating positive and negative anomalies form a stripe-like pattern parallel ridge crest.
Plate Boundaries
- Subduction zones, or convergent margins, where plates collide.
- Divergent margins, where two plates spread apart, occur at seafloor spreading ridges or continental rift zones (ex East Africa Rift).
- Transform margins mark slip-sliding plates (ex. California's San Andreas Fault, where the North America and Pacific plates grind past each other).
Convergent Boundaries:
- Where two plates collide
- Subduction zones occur when one or both plates consist of oceanic crust, where the denser plate is subducted and melted.
- Island arcs and trenches occur when both plates are oceanic crust, with back-arc basins and submarine volcanoes often present.
- Oceanic crust meeting continental crust creates mountain ranges on the continent.
- Continental crusts collide to create large mountain ranges, like the Himalayas.
Divergent Boundaries:
- Where two plates move apart.
- Created space can fill with new crustal material from molten magma.
- Divergent boundaries can form within continents, becoming ocean basins.
- This process creates rifts and rift valleys on land.
- The most active divergent boundaries are between oceanic plates, known as mid-ocean ridges.
Transform Boundaries:
- Where plates slide past each other
- They are occur underwater or on land, crust is neither destroyed nor created.
- Friction prevents smooth gliding, causing stress to build up and the energy released causes earthquakes.
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