Questions and Answers
What type of boundary occurs when plates move away from each other and produce new crust?
Which of the following correctly describes the composition of tectonic plates?
What geological feature is formed at a divergent boundary under the ocean?
Which process results in the formation of 'magnetic stripes' during sea-floor spreading?
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What happens to the age of rocks as one moves away from a mid-ocean ridge?
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What type of plate boundary is characterized by the movement of continental plates splitting into two or more segments?
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Which of the following is an example of a divergent boundary?
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What is the significance of subduction zones in relation to plate age?
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What is the primary composition of the inner core?
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Which layer of the Earth is characterized as semi-liquid and is responsible for the movement of tectonic plates?
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What is the approximate thickness of the outer core?
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What type of rock primarily composes the oceanic crust?
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Which of the following layers of Earth is classified as solid and sits above the asthenosphere?
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At what depth does the Mohorovicic discontinuity separate the crust from the upper mantle?
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Which layer of the Earth is described as having a 'plastic' texture?
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What drives the movement of tectonic plates within the Earth's mantle?
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What is formed as a result of continental plates colliding?
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Which feature is typically associated with an oceanic-continental convergent boundary?
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What type of boundary is characterized by plates sliding past each other?
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What geological event is typically caused by subduction zones?
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Which mountain range exemplifies the result of continental-continental convergence?
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What occurs to the oceanic crust when it subducts beneath continental crust?
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Which of the following is not typically a result of divergent boundaries?
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In oceanic-oceanic convergence, what unique feature is formed?
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Study Notes
Plate Tectonics
- Theory developed from the 1950s to 1970s, evolving from Alfred Wegener's continental drift concept.
- Earth's surface divided into large, thick plates that slowly change size and move.
- Plates comprise the crust and upper mantle, shaped by tectonic interactions.
Plate Boundaries
- Interactions occur at boundaries where two or more plates meet.
- Types of boundaries:
- Convergent
- Divergent
- Transform
Divergent Boundaries
- Characterized by plates moving away from each other, leading to new crust formation.
- Occurrences include continental rift zones (landmass splits) and mid-ocean ridges (elevated sea floor).
- Magma rises to form new oceanic crust, with examples like the Mid-Atlantic Ridge and East Pacific Rise.
- Magnetic stripes form as iron and magnesium minerals align with Earth's magnetic field during sea floor spreading.
Rift Valley Formation
- Youngest rocks located at the rift zone; older rocks move away from it.
- Oldest rocks typically found in subduction zones.
- May eventually create new oceans over time.
Internal Structures of Earth
- Inner Core: Hottest layer, 1,200 km thick, solid iron and nickel, temperatures up to 5,500 °C.
- Outer Core: Liquid layer, 2,300 km thick, comprising iron and nickel, temperatures between 2,260 °C and 4,982 °C.
- Mantle: Approximately 2,900 km thick, semi-liquid and composed of magma, temperatures range from 870 °C to 2,200 °C.
- Asthenosphere: Beneath the lithosphere, extends from 100 km to 700 km below the surface, more fluid than the lithosphere.
Crust Types
- Oceanic Crust: Denser, thinner, primarily basaltic composition.
- Continental Crust: Less dense, thicker, primarily granitic composition.
Discontinuities
- Conorod Discontinuity: Separates upper and lower crust.
- Mohorovicc Discontinuity: Separates lower crust from upper mantle.
- Guttenberg Discontinuity: Separates lower mantle from outer core.
Mechanical and Compositional Layers
- Mechanical Layers: Lithosphere (solid), Asthenosphere (plastic), Mesosphere (solid), Outer Core (molten), Inner Core (solid).
- Compositional Layers: Crust (0-45 km), Mantle (45-2900 km), Core (2900-6371 km).
Convergent Boundaries
- Plates collide, destroying old crust and forming mountains.
- Three types:
- Continental-Continental: Plates push up and crumple to form high mountain ranges (e.g., Himalayas).
- Continental-Oceanic: Oceanic plate subducts underneath continental plate, forming deep trenches and volcanic arcs (e.g., Andes Mountains).
- Oceanic-Oceanic: One oceanic plate subducts, creating deep ocean trenches and volcanic island arcs (e.g., Mariana Trench).
Transform Boundaries
- Plates slide past each other, leading to geological features such as faults (e.g., San Andreas Fault).
Theory of Plate Tectonics
- Earth's lithosphere comprises plates moving over the molten asthenosphere, containing locations such as the Great Rift Valley and Lake Superior.
- Iceland has a significant divergent plate boundary.
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Description
Explore the fundamental concepts of plate tectonics and how oceanic and continental plates interact at their boundaries. Developed through decades of research, this quiz examines the evolution of the theory from its origins in the early 20th century to modern-day understandings.
