Questions and Answers
What is formed when a continental plate collides with another continental plate?
What process is indicated by an oceanic plate sinking beneath another oceanic plate?
Which geological feature is associated with divergent plate boundaries?
What type of fault occurs when the hanging wall moves down relative to the footwall?
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What type of plate boundary results in two plates sliding past each other?
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Which of the following describes a thrust fault?
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What geological phenomenon is created by the rising of magma from the ocean floor at divergent boundaries?
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What is the primary cause of earthquakes at transform boundaries?
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What are the two main types of evidence geologists use to learn about Earth's interior?
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Geologists can directly observe Earth's interior.
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What are the three main layers of Earth?
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The layer beneath the Earth's crust is called the ______.
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What types of rocks primarily make up the oceanic crust?
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What are the two parts of the Earth's core?
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What does the term 'lithosphere' refer to?
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What is the asthenosphere?
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P waves are known as ______ waves.
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S waves are also known as ______ waves.
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Study Notes
Plate Boundaries
- Convergent boundaries form where two tectonic plates collide.
- Types of convergent boundaries include:
- Oceanic-Continental: Oceanic plate subducts under a continental plate, forming trenches.
- Oceanic-Oceanic: The denser oceanic plate subducts under another oceanic plate, creating subduction zones.
- Continental-Continental: Two continental plates collide, resulting in mountain formation in collision zones.
Collision Zones
- Collision zones are characterized by folded and thrust-faulted mountains.
- A subduction zone occurs when oceanic crust sinks back into the mantle at convergent boundaries, leading to deep-ocean trenches.
Divergent Boundaries
- Divergent boundaries occur where two plates move apart, allowing magma to rise and create new crust.
- Causes of divergent boundaries include the formation of mid-ocean ridges, rift valleys, new crust, and volcanoes.
Volcanic Activity
- In Iceland, lava from the ocean floor rises and cools to form new crust, creating rift valleys.
- Iceland has approximately 130 volcanoes, with eruptions typically occurring every 5 to 10 years.
- The East African Rift Valley is an example of a continental rift valley, indicating where the continental lithosphere is weakening and stretching.
Transform Boundaries
- Transform boundaries occur when tectonic plates slide past each other horizontally, potentially causing earthquakes from accumulated pressure.
- The San Andreas Fault in California is a well-known transform fault.
Fault Types
- Fault movements can be classified as:
- Dip-slip: Movement along the fault plane; can be normal (hanging wall moves down) or reverse (hanging wall moves up).
- Strike-slip: Horizontal movement along the fault, defines a strike-slip fault.
- Thrust fault: A reverse fault with a dip angle of 45° or less.
- Oblique slip: A combination of both strike-slip and dip-slip movements.
Fault Mechanics
- Dip refers to the steepness of the fault surface measured from Earth's surface.
- The hanging wall is the block above the fault plane, while the footwall is below it.
Exploring Inside Earth
- Geologists study Earth's interior using direct evidence from rock samples and indirect evidence from seismic waves.
- Rocks can be forced to the surface from depths over 100 km, providing insight into Earth's internal structure.
Seismic Waves and Earth's Layers
- Earthquakes generate seismic waves that geologists record, revealing information about Earth's composition through their speed and behavior.
- Seismic waves indicate that Earth has several concentric layers: the thin outer crust, the mantle, the liquid outer core, and the solid inner core.
- P waves (primary waves) are the fastest seismic waves, while S waves (secondary waves) arrive later.
Earth's Main Layers
- The three primary layers of Earth are:
- Crust: The layer of solid rock forming Earth's outer skin, includes oceanic crust (basalt) and continental crust (granite).
- Mantle: Composed of hot, solid rock, nearly 3000 km thick, divided into the lithosphere and asthenosphere based on characteristics.
- Core: Comprised mainly of iron and nickel, consisting of a liquid outer core and a solid inner core.
Detailed Composition of Layers
-
Crust:
- Oceanic crust: Thinner, mostly basalt, dark and fine textured.
- Continental crust: Thicker, primarily granite, light in color and coarse textured.
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Mantle:
- Lithosphere: Rigid layer formed by the uppermost part of the mantle and crust.
- Asthenosphere: Soft layer beneath the lithosphere, still solid but under pressure and temperature increases.
-
Core:
- Outer core: Molten metal layer surrounding the inner core, remains liquid due to intense pressure.
- Inner core: Solid dense ball of metal where extreme pressure prevents iron and nickel from becoming liquid.
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Description
Test your knowledge on different types of plate boundaries! This quiz covers the interactions between oceanic and continental plates, including subduction zones and collision zones. Dive into the fascinating world of geology and discover how these processes shape our planet.
