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What is the thinnest layer of the Earth's internal structure?
What is the thinnest layer of the Earth's internal structure?
What is the term used to describe the base of the crust?
What is the term used to describe the base of the crust?
What is the thickness of the Lithosphere?
What is the thickness of the Lithosphere?
What is the term used to describe the strong outer layer of the Earth?
What is the term used to describe the strong outer layer of the Earth?
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What is the term used to describe the layer that extends from the base of the Lithosphere to 660 km?
What is the term used to describe the layer that extends from the base of the Lithosphere to 660 km?
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What is the starting temperature of the Asthenosphere?
What is the starting temperature of the Asthenosphere?
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What is the term used to describe the layer that includes the lower part of the Lithosphere and the upper part of the Asthenosphere?
What is the term used to describe the layer that includes the lower part of the Lithosphere and the upper part of the Asthenosphere?
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How do we know the layers of the Earth's internal structure exist?
How do we know the layers of the Earth's internal structure exist?
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What is the region from the 410-km to the 660-km discontinuity known as?
What is the region from the 410-km to the 660-km discontinuity known as?
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What is the estimated temperature at the core-mantle boundary?
What is the estimated temperature at the core-mantle boundary?
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What is the composition of the Outer Core?
What is the composition of the Outer Core?
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What is the temperature at the surface of the Inner Core?
What is the temperature at the surface of the Inner Core?
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What is the Lithosphere composed of?
What is the Lithosphere composed of?
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At what temperature do rocks in the Lithosphere take on a viscous nature and flow?
At what temperature do rocks in the Lithosphere take on a viscous nature and flow?
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What marks the boundary between the Lithosphere and the Asthenosphere?
What marks the boundary between the Lithosphere and the Asthenosphere?
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How do we know the locations of the Lithosphere and Asthenosphere?
How do we know the locations of the Lithosphere and Asthenosphere?
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What is the Lithosphere composed of?
What is the Lithosphere composed of?
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What is the primary cause of the transfer of heat in convection?
What is the primary cause of the transfer of heat in convection?
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What is the process by which heat or electricity is directly transmitted through a substance?
What is the process by which heat or electricity is directly transmitted through a substance?
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How many major plates are the Earth's crust divided into?
How many major plates are the Earth's crust divided into?
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What is the term for the deformation of the crust as a result of plate interaction?
What is the term for the deformation of the crust as a result of plate interaction?
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What is the outer core primarily composed of?
What is the outer core primarily composed of?
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What is the main cause of the Earth's magnetic field?
What is the main cause of the Earth's magnetic field?
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What is the layer below the lithosphere?
What is the layer below the lithosphere?
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What occurs when two oceanic plates collide?
What occurs when two oceanic plates collide?
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What is the result of a collision between two continental plates?
What is the result of a collision between two continental plates?
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What is the term for the boundary where lithosphere is neither created nor destroyed?
What is the term for the boundary where lithosphere is neither created nor destroyed?
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What feature is formed as a result of an oceanic plate being subducted?
What feature is formed as a result of an oceanic plate being subducted?
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What is a characteristic of an island arc?
What is a characteristic of an island arc?
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What is the result of a conservative plate boundary?
What is the result of a conservative plate boundary?
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What is the name of the deepest part of the ocean?
What is the name of the deepest part of the ocean?
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What is a characteristic of a convergent plate boundary?
What is a characteristic of a convergent plate boundary?
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What drives the movement of the plates?
What drives the movement of the plates?
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What is the main difference between oceanic and continental plates?
What is the main difference between oceanic and continental plates?
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What is the process that occurs along the boundaries of a plate?
What is the process that occurs along the boundaries of a plate?
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What type of plate boundary is characterized by plates moving away from each other?
What type of plate boundary is characterized by plates moving away from each other?
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What is the term for the process by which new plate material is added to the lithosphere?
What is the term for the process by which new plate material is added to the lithosphere?
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What is the typical width of ocean ridges?
What is the typical width of ocean ridges?
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What is the characteristic of earthquakes that occur at divergent plate boundaries?
What is the characteristic of earthquakes that occur at divergent plate boundaries?
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What is the approximate percentage of the Earth's surface covered by oceanic plates?
What is the approximate percentage of the Earth's surface covered by oceanic plates?
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Study Notes
Earth's Internal Structure
- Earth's internal structure is divided into three main parts: crust, mantle, and core.
- Crust: 3-70 km thick, ranges from 3 km at oceanic ridges to 70 km in collisional orogens/mountains.
- Mohorovicic discontinuity (Moho) defines the base of the crust.
- Lithosphere: 50-300 km thick, includes the crust and uppermost mantle, thinnest in oceanic regions and thicker in continental regions.
- Asthenosphere: extends from the base of the lithosphere to 660 km, characterized by high temperature and pressure, and viscous flow.
- Upper Mantle: extends from the Moho to the 660 km discontinuity, includes the lower part of the lithosphere and the upper part of the asthenosphere.
- Transition Zone: region from the 410 km to the 660 km discontinuity.
- Lower Mantle: extends from the 660 km discontinuity to the 2900 km discontinuity at the core-mantle boundary.
- Outer Core: extends from the 2900 km to the 5200 km discontinuity, composed of mostly iron and nickel.
- Inner Core: extends from the 5200 km discontinuity to the center of the Earth, primarily a solid ball composed of an iron-nickel alloy.
Lithosphere
- Lithosphere is the outermost layer of Earth, composed of the crust and the brittle part of the upper mantle.
- The term "lithosphere" is derived from the Greek words "lithos" (stone) and "sphaira" (globe or ball).
- At the lithosphere-asthenosphere boundary, rocks take on a viscous nature and flow, albeit very slowly, due to high temperature and pressure.
Plate Tectonics
- Plate tectonics is the concept that the lithosphere is divided into a small number of nearly rigid plates that move over the asthenosphere.
- The Earth's crust is divided into 12 major plates that move in various directions, causing them to collide, pull apart, or scrape against each other.
- Each type of interaction causes a characteristic set of Earth structures or "tectonic" features.
- The word "tectonics" refers to the deformation of the crust as a consequence of plate interaction.
Plate Composition and Movement
- Plates are made of rigid lithosphere, which is composed of the crust and the upper part of the mantle.
- Below the lithosphere is the asthenosphere.
- Plates are moved around by the underlying hot mantle convection cells.
- The Earth's magnetic field originates in the outer core, which is a metallic fluid consisting mainly of iron.
Convection and Conduction
- Convection: the movement of fluid due to differences in temperature and density, resulting in the transfer of heat.
- Conduction: the process of direct heat transfer through a material without movement.
Oceanic and Continental Plates
- Oceanic plates are formed at mid-oceanic ridges, composed of heavy rocks (mafic in nature), dense (approximately 3200 kg/m3), and old (less than 200 million years).
- Continental plates are formed at subduction zones, composed of lighter rocks (felsic in nature), less dense (approximately 2600-2750 kg/m3), and older (up to 4 billion years).
- Oceanic plates cover approximately 71% of the Earth's surface, while continental plates cover 29%.
Plate Boundaries
- There are three types of plate boundaries: divergent, convergent, and conservative.
- Divergent plate boundaries: plates move away from each other, resulting in the creation of new plate material.
- Convergent plate boundaries: plates move towards each other, resulting in subduction, collision, or destruction of plate material.
- Conservative plate boundaries: plates slide past each other, resulting in faults and magma outflow.
Convergent Plate Boundaries
- Collision of oceanic plates: one plate subducts beneath the other, forming a subduction zone and trench.
- Collision of continental plates: plates collide and push against each other, resulting in intense folding, faulting, and mountain formation.
Conservative Plate Boundaries
- Along conservative boundaries, lithosphere is neither created nor destroyed, and plates move laterally relative to each other.
- Examples include the San Andreas Fault in California, USA.
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Description
This quiz covers the basics of Earth's internal structure, including the crust, mantle, and core. Learn about the importance of the lithosphere and how we know about the internal structure of the Earth.