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Questions and Answers
What type of fault is formed when two plates slide horizontally past each other in opposite directions?
What is the name of the famous fault in California that is an example of a strike-slip fault?
What type of plate boundary is characterized by strike-slip faults?
What is the primary mechanism that causes earthquakes at strike-slip faults?
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What is the characteristic of a plate that allows it to move horizontally over the asthenosphere?
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What is the term for the geological activity that occurs at strike-slip faults?
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What is the result of the downward movement of convection currents?
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What is the result of the horizontal motion of plates at strike-slip faults?
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What is the name of the process that describes the movement of warmer particles upwards and cooler particles downwards?
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What is the location of the seven major plates?
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What is the rate at which plates move?
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What is the term used to describe the movement of plates that pass each other horizontally?
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What percentage of earthquakes occur in the Pacific Ring of Fire?
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What is the result of convergent plate boundaries where an oceanic plate meets a continental plate?
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What is the main cause of volcanoes and earthquakes?
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What type of plate boundary is characterized by two plates moving apart?
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How many major tectonic plates are there on Earth?
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What is the name of the underwater mountain range in the Atlantic Ocean?
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Study Notes
Plate Tectonics and Boundaries
- Large mountain chains, such as the Himalayas and Alps, form at transform plate boundaries.
- At transform boundaries, two tectonic plates slide horizontally past each other in opposite directions, creating strike-slip faults like the San Andreas Fault and leading to earthquakes.
- Intraplate activities occur within tectonic plates and are not confined to boundaries; these include mantle plumes and hot spots that can cause volcanism.
Earth's Internal Structure
- The core consists of an outer liquid layer and an inner solid layer, primarily composed of iron (Fe) and nickel (Ni).
- The mantle is composed mainly of silicates (Si and O) and features convection currents that drive tectonic movements.
- The crust is categorized into continental (low density) and oceanic (high density) types, contributing to different geological features.
Lithosphere and Asthenosphere
- The lithosphere is a rigid, solid layer comprised of the upper mantle and crust, while the asthenosphere is a highly viscous layer that allows tectonic plates to move.
- Tectonic plates float on the asthenosphere and can carry both continental and oceanic crusts, moving very slowly at rates of 1-16 cm per year.
Theories of Plate Movements
- Alfred Wegener proposed the theory of continental drift, stating that continents were once a single landmass, later breaking into smaller supercontinents, supported by the continental jigsaw puzzle analogy.
- Harry Hess introduced the seafloor spreading theory, explaining that hot material from below the crust rises to create new seafloor, forming mid-ocean ridges.
Major and Minor Tectonic Plates
- There are seven major tectonic plates: African, Antarctic, Eurasian, Indo-Australian, North American, Pacific, and South American.
- Minor plates include Caribbean, Scotia, Arabian, Indian, Philippine, Juan de Fuca, Cocos, and Nazca.
- Plates can collide, separate, or slide past each other, leading to various geological features.
Plate Movement Mechanisms
- Convective currents in the mantle drive plate movements: warmer, less dense material rises while cooler material sinks, leading to either divergence (new crust) or convergence (subduction).
Evidence Supporting Plate Movements
- The fit between coastlines (e.g., South America and Africa) supports the idea of shifting continents.
- Similarities in rock layers and mountain ranges (Circum-Pacific Belt, Mid-Atlantic Ridge, Mid-Continental Belt) provide further evidence for plate tectonics.
Earthquakes and Volcanoes
- Earthquakes typically occur along plate boundaries, with 70% of global earthquakes happening in the Pacific Ring of Fire.
- Volcanoes and earthquakes are produced by the interactions of tectonic plates at their boundaries.
Types of Plate Boundaries
- Divergent boundaries occur when plates move apart, forming new crust and features like mid-ocean ridges and rift valleys.
- Convergent boundaries occur when plates collide, leading to subduction and the formation of mountains and volcanic arcs, such as the Andes or Japan's islands.
- Types of convergent boundaries include:
- Oceanic-Continental: Results in volcanism along subduction zones.
- Oceanic-Oceanic: Forms island arcs and ocean trenches.
- Continental-Continental: Produces major mountain ranges through folding and collision.
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Description
This quiz covers the formation of large mountain chains, transform plate boundaries, and geological activities within tectonic plates. It explores topics such as strike-slip faults, intraplate activity, mantle plumes, and hot spots.
