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Questions and Answers
What is the primary driving force behind endogenic processes?
What is the primary driving force behind endogenic processes?
Which of the following best describes magmatism?
Which of the following best describes magmatism?
What term refers to the eruption of molten rock onto the surface of a planet?
What term refers to the eruption of molten rock onto the surface of a planet?
Which of the following is NOT an agent of metamorphism?
Which of the following is NOT an agent of metamorphism?
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What is the result of compression stress on rocks?
What is the result of compression stress on rocks?
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What is a characteristic feature of shear stress?
What is a characteristic feature of shear stress?
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In which type of fault does the upper block move up and over the lower block?
In which type of fault does the upper block move up and over the lower block?
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Which type of deformation refers to a rock's response to applied stress?
Which type of deformation refers to a rock's response to applied stress?
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What is the main concept of the Continental Drift Theory?
What is the main concept of the Continental Drift Theory?
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What major scientific advancement was achieved in the 1960s regarding tectonics?
What major scientific advancement was achieved in the 1960s regarding tectonics?
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Which of the following correctly describes Pangaea?
Which of the following correctly describes Pangaea?
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Which factor contributed to the rejection of Wegener's proposal of continental drift?
Which factor contributed to the rejection of Wegener's proposal of continental drift?
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What evidence did Wegener present to support the idea of continental drift?
What evidence did Wegener present to support the idea of continental drift?
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During which period did Pangaea begin to break up into Laurasia and Gondwanaland?
During which period did Pangaea begin to break up into Laurasia and Gondwanaland?
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Which type of plate boundary is characterized by the movement of two plates apart?
Which type of plate boundary is characterized by the movement of two plates apart?
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What is the primary characteristic of a conservative plate boundary?
What is the primary characteristic of a conservative plate boundary?
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Which of the following is NOT one of the seven major tectonic plates?
Which of the following is NOT one of the seven major tectonic plates?
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How does the Continent Accretion Theory view the movement of continents?
How does the Continent Accretion Theory view the movement of continents?
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Which hypothesis explains how ocean areas accumulated denser elements that formed basins?
Which hypothesis explains how ocean areas accumulated denser elements that formed basins?
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What is a significant piece of evidence against the idea that continents have always been stationary?
What is a significant piece of evidence against the idea that continents have always been stationary?
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What is the primary feature of a subduction zone?
What is the primary feature of a subduction zone?
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What characteristic is associated with the Expanding Earth Hypothesis?
What characteristic is associated with the Expanding Earth Hypothesis?
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Wegener’s observations of fossil similarities were explained by which concept?
Wegener’s observations of fossil similarities were explained by which concept?
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Where does seafloor spreading primarily occur?
Where does seafloor spreading primarily occur?
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What occurs when two continental plates converge?
What occurs when two continental plates converge?
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Which statement is true about oceanic-continental convergent boundaries?
Which statement is true about oceanic-continental convergent boundaries?
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What evidence did Wegener use to support the concept of continental drift?
What evidence did Wegener use to support the concept of continental drift?
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Which of the following statements reflects a misconception about continental drift?
Which of the following statements reflects a misconception about continental drift?
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Which of the following accurately describes an oceanic-oceanic convergent boundary?
Which of the following accurately describes an oceanic-oceanic convergent boundary?
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Study Notes
Endogenic Processes
- Processes that occur beneath the Earth's surface, driven by internal heat.
- Result of radioactive decay of elements in Earth's core.
- Force behind bending, cracking, lifting, and moving Earth's outer layer.
Magmatism
- Magma is molten or semi-molten rock found beneath the Earth's surface.
- Crucial for mountain formation, as rising magma adds mass to the surface and subsurface.
- Leads to the development of igneous (magmatic) rocks.
Volcanism (Plutonism)
- Volcanoes are vents for magma and gas discharge.
- Magma that reaches the surface is known as lava.
- Volcanoes are named after Vulcan, the Roman god of fire.
- Volcanism involves the eruption of molten rock onto the surface.
Metamorphism
- Refers to the change in rock structure and mineralogy due to varying conditions from their original formation.
- Excludes changes caused by surface processes like compaction.
- Major factors influencing metamorphism are temperature, pressure, and fluids.
Deformation
- Refers to changes in rock shape or size due to applied stress.
Classification of Deformation of Rocks
- Stress: The force applied to a rock that can cause deformation.
- Faulting: A fracture in the Earth's crust resulting from the displacement of one side relative to the other.
Types of Stress
- Compression: A type of stress that reduces the volume of a material.
- Tension: A type of stress that pulls a material apart.
- Shear: A type of stress that causes material to twist.
Faulting
- Normal Fault: A dip-slip fault where the block above the fault moves downwards relative to the block below.
- Reverse Fault: A dip-slip fault where the upper block moves upwards and over the lower block.
- Strike-Slip Fault: A fault where the two blocks slide past each other horizontally.
Plate Motion
- Plate motions cause mountains to form where plates collide (converge) and continents to fracture and oceans to form where plates move apart (diverge).
- Continents are embedded in these plates and drift passively, leading to significant geographic changes over millions of years.
Plate Motion: Early Theories and Hypothesis
- Continent Accretion Theory: Proposed that continents were stationary with gradual additions of new material.
- Continent Assimilation Hypothesis: Explained the formation of ocean basins by denser elements sinking.
- Expanding Earth Hypothesis: Suggested that continents split due to Earth's expansion, with the current continents representing half of the original Earth's surface area.
Plate Motion: Modern Theory
- Continental Drift Theory: Explains the gradual movement of continents over time.
- The Earth's upper layer is broken into large slabs called plates, which sit on a fluid layer of molten rock (mantle).
- The movement of the molten layer, known as plate tectonics, causes the plates to shift.
- Alfred Wegener (1912): A German geophysicist and meteorologist who proposed the Continental Drift Theory.
- Pangaea: Wegener theorized that continents were once joined as a single landmass called Pangaea (275-175 million years ago), surrounded by the ocean "Panthalassa".
- Laurasia and Gondwanaland: During the Jurassic period, Pangaea split into two smaller supercontinents, Laurasia and Gondwanaland. By the end of the Cretaceous period, these continents further separated into the modern landmasses we know today.
4 Evidences of Continental Drift
- Continental Jigsaw Puzzle: The remarkable similarity between the coastlines of certain continents, like South America and Africa, suggested a possible past connection.
- Fossil Correlation: Similar fossil plants and animals found on different continents support the idea of a once-unified landmass.
- Rock and Mountain Correlation: Continuous rock types and mountain ranges, like the Appalachian Mountains and the Caledonian Mountains, further suggest a shared geological history.
- Paleoclimatic Data: Glacial deposits indicate that during the Paleozoic era, ice sheets covered significant areas of the Southern Hemisphere, supporting the idea of a once-connected landmass.
Rejecting the Continental Drift
- Wegener faced criticism for his inability to explain the mechanism behind continental drift.
- His explanation of fossil similarities through land bridges was met with skepticism.
- His background as a meteorologist, not a geologist, contributed to resistance from the scientific community.
- His initial calculations for continental movement speed proved to be inaccurate.
Plates of the World
- 7 Major Plates: Pacific Plate, African Plate, North American Plate, Indo-Australian Plate, South American Plate, Eurasian Plate, Antarctic Plate.
- Largest Minor Plates: Juan de Fuca Plate, Arabian Plate, Caribbean Plate, Cocos Plate, Nazca Plate, Philippine Plate, Scotia Plate.
Plate Tectonics
- Plate tectonics is a theory that explains the formation of major landforms due to the Earth's internal movements.
- This theory, solidified in the 1960s, revolutionized earth sciences by explaining phenomena like mountain building, volcanic activity, and earthquakes.
Plate Boundaries
- Found at the edges of lithospheric plates.
- There are three types of boundaries: Convergent, Divergent, and Conservative.
- Plate boundaries represent zones where the velocity of one plate changes relative to the adjacent plate.
Types of Plate Boundaries
- Divergent Boundary: Also known as constructive margins, where two plates move apart. This leads to the upwelling of material from the mantle, creating new seafloor.
- Convergent Boundary: Also known as destructive margins, where two plates collide. This results in oceanic lithosphere being pushed beneath an overriding plate, eventually being reabsorbed into the mantle. Collisions between continental plates can also form mountain systems.
- Subduction Zone: A specific type of convergent boundary where one plate (usually oceanic) sinks into the mantle beneath another plate.
Types of Convergent Boundary
- Oceanic-Continental: The denser oceanic plate subducts beneath the less dense continental plate, creating a chain of volcanoes on the continental side.
- Oceanic-Oceanic: Two oceanic plates collide, and one subducts beneath the other. This results in the formation of a volcanic island arc.
- Continental-Continental: Two continental plates collide and push upwards due to both having similar densities, leading to the formation of large mountain ranges.
Seafloor Spreading
- A geological process where tectonic plates move apart due to mantle convection (the slow, churning motion of Earth's mantle).
- This occurs at divergent plate boundaries.
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Description
Explore the fundamental concepts of endogenic processes including magmatism, volcanism, and metamorphism. This quiz covers how these internal processes shape the Earth's structure and lead to the formation of various rock types. Test your knowledge on the dynamics beneath the surface.
