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Questions and Answers
Which type of crust is characterized by being less dense and consists mainly of granite rock?
Which type of crust is characterized by being less dense and consists mainly of granite rock?
What type of plate boundary is formed when plates slide past each other?
What type of plate boundary is formed when plates slide past each other?
Which phenomenon is associated with the creation of hotspots?
Which phenomenon is associated with the creation of hotspots?
Which type of rock is formed when molten rock cools and solidifies?
Which type of rock is formed when molten rock cools and solidifies?
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At what thickness is oceanic crust typically found?
At what thickness is oceanic crust typically found?
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Which of the following describes the age distribution of rocks along a mid-ocean ridge?
Which of the following describes the age distribution of rocks along a mid-ocean ridge?
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What is the primary characteristic of basalt rock compared to granite?
What is the primary characteristic of basalt rock compared to granite?
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Which type of boundary is responsible for forming ridges as plates spread apart?
Which type of boundary is responsible for forming ridges as plates spread apart?
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What is the composition of the inner core of the Earth?
What is the composition of the inner core of the Earth?
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Which factor affects the speed of seismic waves the least?
Which factor affects the speed of seismic waves the least?
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How do solid materials compare to liquid materials in terms of seismic wave transmission?
How do solid materials compare to liquid materials in terms of seismic wave transmission?
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What is a characteristic of Earth's magnetic field?
What is a characteristic of Earth's magnetic field?
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What happens to solar wind particles as they approach Earth?
What happens to solar wind particles as they approach Earth?
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What type of igneous rock is formed when magma cools slowly beneath the Earth's surface?
What type of igneous rock is formed when magma cools slowly beneath the Earth's surface?
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Which of the following processes leads to the formation of sedimentary rocks?
Which of the following processes leads to the formation of sedimentary rocks?
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What is the average thickness of the Earth's crust beneath oceans?
What is the average thickness of the Earth's crust beneath oceans?
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Which type of rock is specifically known for preserving fossils?
Which type of rock is specifically known for preserving fossils?
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Which mountain ranges were formed due to continental to continental collisions?
Which mountain ranges were formed due to continental to continental collisions?
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What type of heat and pressure condition leads to the formation of metamorphic rocks?
What type of heat and pressure condition leads to the formation of metamorphic rocks?
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Which type of igneous rock is formed from lava that cools quickly at the surface during a volcanic eruption?
Which type of igneous rock is formed from lava that cools quickly at the surface during a volcanic eruption?
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Which of the following statements is true about the Earth's crust?
Which of the following statements is true about the Earth's crust?
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What is the primary composition of the Earth's mantle?
What is the primary composition of the Earth's mantle?
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At what radius does the Lehman Discontinuity occur?
At what radius does the Lehman Discontinuity occur?
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Which of the following best describes the outer core's viscosity?
Which of the following best describes the outer core's viscosity?
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What process allows the asthenosphere to contribute to tectonic movements?
What process allows the asthenosphere to contribute to tectonic movements?
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Which materials are classified as volatiles that can become gases at surface temperatures?
Which materials are classified as volatiles that can become gases at surface temperatures?
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What occurs at the boundary between the liquid outer core and the solid inner core?
What occurs at the boundary between the liquid outer core and the solid inner core?
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What is the density of the inner core at a radius of 1220 km?
What is the density of the inner core at a radius of 1220 km?
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Which layer of the Earth is characterized as the most homogenous part?
Which layer of the Earth is characterized as the most homogenous part?
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What phenomenon is caused by ions escaping and being pulled to the magnetic poles?
What phenomenon is caused by ions escaping and being pulled to the magnetic poles?
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Which seismic wave type is characterized by ups and downs in motion?
Which seismic wave type is characterized by ups and downs in motion?
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What layer of the Earth is the outermost and thinnest?
What layer of the Earth is the outermost and thinnest?
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Which layer of the Earth is described as the weak layer on which the lithosphere floats?
Which layer of the Earth is described as the weak layer on which the lithosphere floats?
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Which type of seismic wave travels faster and moves side to side?
Which type of seismic wave travels faster and moves side to side?
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What creates light in the upper atmosphere, leading to spectacular auroras?
What creates light in the upper atmosphere, leading to spectacular auroras?
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Which type of seismic waves tend to have larger amplitudes and are slower than body waves?
Which type of seismic waves tend to have larger amplitudes and are slower than body waves?
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Study Notes
Two Types of Crust/Plate
-
Continental Crust
- Less dense
- Composed of Granite Rock
- 20-50km thick
- Older than oceanic crust
-
Oceanic Crust
- More dense
- Composed of Basalt Rock (younger than continental rock)
- 5-10km thick
- Younger, youngest at mid-ocean ridges, older away from ridges
- Mirror image across the ridge
Plate Boundaries
-
Divergent Boundaries
- Forms mid-ocean ridges
- Plates move apart, new material erupts to fill the gap
-
Convergent Boundaries
- Forms mountains, trenches
- Continental to Continental Collision: slow motion, forms mountains like the European Alps, Swiss Alps, Himalayas
-
Transform Boundaries
- Plates slide past each other horizontally
- Example: San Andreas Fault
HotSpots
- Hot magma plumes breaching the Earth's surface in the middle of a tectonic plate
- Example: Hawaii Island (Kawai, Oahu, Maui) and Reunion Island
Three Types of Rocks
-
Igneous Rock
- "Fiery"
- Molten rock cools and solidifies
- Intrusive Igneous Rocks form when magma cools slowly beneath the surface of the Earth (e.g., Granite)
- Extrusive Igneous Rocks form when lava cools at the surface during volcanic eruptions (e.g., Tuff, Obsidian, Pumice)
- Makes up about 95% of the Earth's crust.
-
Sedimentary Rock
- Formed from sediments (sand, mud, organic material) that accumulate over time in deposits, often lakes or oceans
- Layers are squeezed and compressed, forming solid rock
- Types of rocks in which fossils may be found
- Examples: Limestone, Shale, Sandstone
-
Metamorphic Rock
- "To change form"
- Formed by extreme heat and pressure
- Can be formed deep underground
- Examples: Marble, Slate
The Crust
- Shallowest layer of the Earth
- Most heterogeneous layer
- Average thickness: 22km for continents, 10km for oceans, varies globally
- Solid rock layer between the crust and the core
The Mantle
- 2885km thick (82% of Earth's volume)
- Composed of ultramafic rock called periodite
- Hot mantle rises, cold mantle sinks
- Magma: molten rock beneath the surface
- Lava: molten rock at the surface
Earth's Core
- Outer core (liquid): mostly an iron-nickel alloy, flows km per year, creates Earth's magnetic field
- Inner core (solid): iron-nickel alloy, density of 13 g/cm^3, radius of 1220km
- Lehman Discontinuity (boundary between outer and inner core): 1220km
- Earth gradually cools, causing the core to freeze, releasing latent heat, which drives convection in the outer core
Mechanical Layers
- Lithosphere: crust and a part of the upper mantle, makes up tectonic plates
- Asthenosphere: weak layer of the mantle on which the lithosphere floats
- Mesosphere: lower mantle, more rigid than the asthenosphere
Convection
- Movement of heat within the mantle
- Drives tectonic processes
- Hotter, less dense materials rise
- Cooler, denser materials sink
Earthquakes
- Sudden movement of materials within the Earth, often along faults
- Energy is transmitted as seismic waves
- Velocity of seismic waves changes with density, giving information about the depth and composition of Earth's layers
- Reflections (energy bounces off harder layers) and refractions (energy bends, changing direction) provide information about the Earth's interior
Seismic Waves
-
Body Waves: travel through the Earth
- P-waves (Primary Waves): compressional waves, fastest, travel through solids and liquids
- S-waves (Secondary Waves): shear waves, slower, travel only through solids
-
Surface Waves: travel along Earth's surface
- Rayleigh Waves: up and down motion
- Love Waves: sideways motion, faster than Rayleigh waves
-
Factors affecting seismic wave propagation:
- Distance
- Density
- Temperature
- Liquid vs solid
- Angle of incidence
Earth's Magnetic Field
- Dipolar, with a north and south pole
- Solar wind (charged particles from the sun) is deflected by Earth's magnetic field
- Van Allen Belts: charged particles trapped in the Earth's magnetic field
- Aurora Borealis: Northern Lights, caused by charged particles interacting with the atmosphere near the North Pole
- Aurora Australis: Southern Lights, caused by charged particles interacting with the atmosphere near the South Pole
Volatiles
- Materials that turn into gas at the surface of the Earth
- Examples: H2O, CO2, CH4, and SO2
- Released during volcanic eruptions
Summary
- The Earth is composed of three major layers: crust, mantle, and core (outer and inner core)
- The crust is the outermost and thinnest layer.
- The mantle is the middle layer, making up most of the Earth's volume and mass.
- The lithosphere (crust and upper mantle) is subdivided into tectonic plates.
- The asthenosphere is the weak layer of the mantle on which the lithosphere floats.
- The outer core is liquid and creates the Earth's magnetic field.
- The inner core is solid and is the deepest layer of the Earth.
- Seismic wave properties (speed, reflection, refraction) are used to study the interior of the Earth.
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Description
Explore the fundamental concepts of Earth's crust and plate tectonics in this quiz. Learn about the characteristics of continental and oceanic crust, the different types of plate boundaries, and the significance of hotspots. Test your knowledge on geological processes and rock types related to plate tectonics.
