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Questions and Answers
What is the primary composition of the inner core?
Which layer of the Earth is known for its flexibility and ability to flow like a viscous liquid?
How thick is the Earth's crust beneath the oceans?
What temperature range does the outer core reach?
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Which of the following statements about the lithosphere is correct?
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What is the main factor driving the movement of tectonic plates?
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What distinguishes oceanic crust from continental crust?
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What is the athenosphere primarily composed of?
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What is the primary composition of the continental crust?
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Which layer of the Earth is considered the rigid outer layer that includes both the crust and upper mantle?
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What characteristic distinguishes oceanic crust from continental crust?
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What is the approximate annual movement rate of tectonic plates?
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Which of the following phenomena are typically found along tectonic plate boundaries?
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Which term refers to the long, steep-sided valleys on the ocean floor?
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Which of the following best defines the term 'asthenosphere'?
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What is the definition of an earthquake?
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What happens to the age of ocean crust as one moves away from the oceanic ridge?
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How do rocks at the mid-ocean ridge compare in age to those found far away from it?
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What role does sonar play in oceanography?
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What is the significance of magnetic reversals in oceanic crust formation?
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What material primarily composes the oceanic crust?
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How long does it normally take for Earth's magnetic field to reverse?
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What tool did scientists start using in the 1950s to measure the magnetism of the ocean floor?
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What is the relationship between sediment thickness and distance from the mid-ocean ridge?
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What is the name of the single large landmass that existed about 200 million years ago?
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Which fossil group did Alfred Wegener use as biogeographic evidence for continental drift?
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What geological evidence supports the theory of continental drift by showing matching large-scale features across continents?
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What do scientists believe drives the movement of tectonic plates?
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Which evidence indicates that Antarctica was once in a much warmer climate?
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What type of geological feature can provide evidence of past glacial movement across continents?
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In which period did the geological changes leading to the current distribution of continents begin to significantly occur?
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What is the term for the theory that describes the gradual movement of the Earth's tectonic plates?
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What primarily causes convection currents in the mantle?
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What role does the slab pull force play in plate tectonics?
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What defines the asthenosphere?
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What happens during the process of seafloor spreading?
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What is the main characteristic of the lithosphere?
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What initiates convection within the Earth's mantle?
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Which process results from the differences in density between old and new oceanic crust?
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What factors contribute to the movement of lithospheric plates?
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Study Notes
Earth Layers
- Earth consists of four main layers: Crust, Mantle, Outer Core, Inner Core.
- Crust: The thin, solid outer layer, 5-35 km thick on land and 1-8 km thick beneath oceans, divided into tectonic plates.
- Mantle: The thickest layer at 2900 km, consisting of the lithosphere and asthenosphere, with temperatures from 1600°F near the surface to 4000°F at the core.
- Outer Core: A liquid layer of iron and nickel, 2,250 km thick, with temperatures between 4000-9000°F.
- Inner Core: Solid due to extreme heat and pressure, primarily composed of iron and nickel.
The Mantle
- Holds the lithosphere (rigid outer layer) and asthenosphere (semi-fluid layer).
- The asthenosphere allows tectonic plates to move, functioning like a thick liquid.
Types of Crust
- Two types: Continental Crust (thicker, less dense, granite-rich) and Oceanic Crust (thinner, denser, basalt-rich).
- Continental crust is primarily old, while oceanic crust is formed at mid-ocean ridges and is comparatively younger.
Plate Tectonics Theory
- Describes the movement of Earth’s lithosphere, which is broken into tectonic plates that interact at boundaries.
- Movement causes earthquakes, volcanoes, and mountain ranges.
- Plates move at rates of 1-10 cm per year due to uneven heat distribution in the Earth.
Continental Drift Theory
- Proposed by Alfred Wegener, describes how continents were once joined as Pangaea.
- Evidence includes:
- Geological fit of coastlines (e.g., South America and Africa).
- Fossil correlation showing similar species across continents.
- Coal deposits in Antarctica indicating a previously warmer climate.
- Glacial striations and deposits matching across separated landmasses.
Convection Currents
- Drive the movement of tectonic plates.
- Result from heat generated by the Earth's core, where hot material rises and cool material sinks.
Other Forces in Plate Movement
- Slab pull: Heavier subducting plates pull down trailing slabs.
- Ridge push: Older oceanic crust sinks due to weight from raised ridges.
Seafloor Spreading Theory
- Suggests that magma rises at mid-ocean ridges, creating new oceanic crust and pushing existing crust sideways.
- Evidence includes younger rocks and thinner sediments at mid-ocean ridges compared to older and thicker rocks further away.
Magnetic Reversal
- Earth's magnetic field has reversed polarity every 500,000 years.
- These reversals are recorded in the basaltic rocks of the ocean floor, supporting seafloor spreading.
Tools for Study
- Sonar: Used to map the ocean floor by sending sound waves and measuring their echo.
- Magnetometers: Measure the magnetic properties of ocean floor rocks.
Key Definitions
- Geology: Scientific study of Earth’s origin, history, and structure.
- Lithosphere: Rigid outer layer of Earth, comprising crust and upper mantle.
- Mantle: Layer between crust and core, characterized by plasticity.
- Tectonic: Relating to movements of Earth’s plates.
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Description
Explore the four main layers of the Earth: the crust, mantle, outer core, and inner core. This quiz covers the characteristics of each layer, including their thickness, composition, and temperature. Test your knowledge about the Earth's structure and its unique features!