Questions and Answers
What theory explains the movement of Earth's tectonic plates due to convection currents in the mantle?
What is the primary reason Continental Drift Theory was initially rejected?
Which of the following describes a convergent plate boundary?
What geological feature is formed when two tectonic plates slide apart at a divergent boundary?
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Which tectonic plate is considered the largest?
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What occurs at transform plate boundaries?
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Why is it said that transform plate boundaries are conservative?
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What is the primary component of the Earth's inner core?
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Where do the majority of earthquakes occur?
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What percentage of Earth's mass is composed of the mantle?
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Study Notes
Plate Tectonics
- Theory established in 1915 that explains Earth's crust is divided into moving plates.
- Movement driven by convection currents in the mantle, where hot molten materials rise and fall.
Continental Drift Theory
- Proposed by Alfred Wegener in 1912, suggesting continents drift apart due to the Earth's polar motion.
- Rejected initially due to insufficient evidence.
- Suggests all continents were once part of the supercontinent Pangaea, surrounded by the ocean Panthalassa.
Tectonic Plates
- Also known as lithospheric plates, they are large slabs of solid rock that form Earth's crust.
- Primary tectonic plates include Pacific, North American, Antarctic, South American, African, Eurasian, and Indian-Australian plates.
- Secondary plates include Caribbean, Nazca, Cocos, Scotia, Arabian, Philippine, and Juan de Fuca plates.
Types of Plate Movement
- Mantle Convection: Hot mantle material rises, transfers heat, and creates movement.
- Slab Pull: Denser oceanic plates sink under lighter continental plates at convergent boundaries.
- Ridge Push: Occurs at divergent boundaries where magma rises, pushing plates apart.
Plate Boundaries
- Convergent Boundaries (Destructive): Plates collide, leading to earthquakes and subduction.
- Divergent Boundaries (Constructive): Plates separate, allowing magma to rise and create new crust.
- Transform Boundaries (Conservative): Plates slide past each other without crust destruction or formation.
Internal Structure of the Earth
- Layers: Crust (0.5% mass), Mantle (80% mass), Core (15% volume).
- Seismic waves and rock samples are key in understanding Earth's interior.
- Oceanic crust is generally younger and primarily composed of basalt, while continental crust is older and more stable.
Earthquake Dynamics
- Result from energy release due to faulting in Earth's crust.
- Most frequent earthquakes occur along the Pacific Ring of Fire (90% occurrence).
- Major earthquake activity also recorded in the Mediterranean-Asiatic belt.
Fault Types
- Normal Fault: Tensional forces at divergent boundaries.
- Strike-Slip Fault: Shear forces at transform boundaries.
- Reverse Fault: Compressional forces at convergent boundaries.
Elastic Rebound Theory
- Proposed by Harry Fielding Reid, explaining energy release during earthquakes through friction, pressure, and force buildup.
- Notable earthquakes: Valdivian earthquake in Chile, 1990 Luzon earthquake in the Philippines.
Seismic Wave Characteristics
- Body Waves: Include Primary (P) waves (compressional) and Secondary (S) waves (shear).
- Surface Waves: Lower frequency, responsible for most earthquake damage.
- Wave behavior characterized by refraction as they move through different layers.
Methods to Locate Earthquakes
- Triangulation Method: Uses data from at least three seismic stations to locate earthquake epicenters.
- Mohorovicic Discontinuity: Boundary identified by Andrija Mohorovicic, separating crust and mantle.
Historical Geological Developments
- Pangaea Formation: Supercontinent formed approximately 250-300 million years ago.
- Theories supported by geological, climatic, and fossil evidence indicating past continental connections.
Seafloor Spreading
- Process of new material addition to ocean floor at mid-ocean ridges, pushing older material away.
- Evidence includes basalt pillows from molten materials and sonar technology for mapping underwater terrain.
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Description
Test your knowledge on Plate Tectonics and its fundamental principles. Explore the discovery of the theory through Alfred Wegener's Continental Drift Theory and understand the movement of Earth's plates. This quiz will help you solidify your understanding of these essential scientific concepts.
