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Questions and Answers
What is the primary cause of the movement of tectonic plates?
What is the primary cause of the movement of tectonic plates?
Which type of plate boundary is characterized by plates moving apart due to tension forces?
Which type of plate boundary is characterized by plates moving apart due to tension forces?
At which type of plate boundary do two plates collide, causing potential subduction?
At which type of plate boundary do two plates collide, causing potential subduction?
What averaging speed is described for the movement of tectonic plates?
What averaging speed is described for the movement of tectonic plates?
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Which term describes the geological feature that forms at divergent plate boundaries?
Which term describes the geological feature that forms at divergent plate boundaries?
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What primarily distinguishes a tectonic earthquake from a volcanic earthquake?
What primarily distinguishes a tectonic earthquake from a volcanic earthquake?
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Which of the following best describes the concept of plate tectonics as proposed in the 1960s?
Which of the following best describes the concept of plate tectonics as proposed in the 1960s?
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How deep do the tectonic plates that form the Earth's lithosphere typically extend?
How deep do the tectonic plates that form the Earth's lithosphere typically extend?
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What is the primary process through which seismic waves are generated during tectonic earthquakes?
What is the primary process through which seismic waves are generated during tectonic earthquakes?
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Which of the following statements is true about the movement of tectonic plates?
Which of the following statements is true about the movement of tectonic plates?
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Study Notes
Earth's Layers
- The Earth's crust is composed of large, stable rigid rock slabs called plates.
- Plates are approximately 100km thick and consist of the crust or lithosphere and part of the upper mantle.
- The crust is the outer rock layer, ranging in thickness from 25-60km under continents and 4-6km under oceans.
- The Mantle lies beneath the crust, extending from 30km-2900km.
Plate Movement
- Large tectonic forces occur at the plate edges due to relative movement of the lithosphere-asthenosphere complex.
- Plate movement is driven by convection currents in the mantle.
- The velocity of plate movement is approximately 1 to 10 cm/year.
Plate Boundaries
- There are three principal types of plate boundaries: divergent, convergent, and transform.
Divergent Plate Boundaries
- Plates separate from each other either through magma effusion or lithosphere divergence from the Earth's interior.
- Mid-ocean ridges are formed by sea-floor spreading/rifting, marking the divergent boundary between two tectonic plates.
- The Mid-Atlantic Ridge is an example of a divergent boundary.
- Divergent plate boundaries are characterized by tension as the plates move apart.
Convergent Plate Boundaries
- Adjacent plates converge and collide.
- There are two types of convergent boundaries: oceanic and continental lithosphere boundaries.
- The Circum-Pacific and Eurasian belts are examples of convergent boundaries.
- Convergent plate boundaries are characterized by compression as the plates come together.
Transform Plate Boundaries
- Two plates glide past one another without subducting old lithosphere.
- The San Andreas fault in California is an example of a transform boundary.
- Transform plate boundaries are characterized by shearing as the plates slide past each other.
Earthquakes
- Tectonic earthquakes are produced by sudden movement along faults and plate boundaries.
- Volcanic earthquakes are induced by rising lava or magma beneath active volcanoes.
Theory of Plate Tectonics
- The theory of plate tectonics was proposed in the 1960s, building upon the theory of continental drift.
- The theory explains the formation and deformation of the Earth's surface.
- According to the theory, continents are carried along on huge slabs (plates) on the Earth's outermost layer (Lithosphere).
- The Earth's outermost layer is divided into 15 major tectonic plates, extending approximately 80km deep.
- These plates move relative to each other a few centimeters per year.
Evidence for Continental Drift
- Matching coastlines
- Matching mountain ranges
- Matching rock types and rock ages
- Matching glacier deposits
- Matching fossils
Seismic Belts
- Earthquakes are recognized as symptoms of active tectonic movements.
- Intense seismic activity is observed and confirmed to occur predominantly on plate boundaries.
- These areas are known as seismic belts.
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Description
Explore the structure of the Earth's layers, including the crust and mantle. Understand the types of plate boundaries and the mechanisms driving plate movement, including convection currents and tectonic forces. Test your knowledge on landforms created by these processes.
