Earth's Layers
What are Earth’s three compositional layers?
Crust, mantle, core
Name one direct way scientists study Earth’s interior
Drilling, lava from volcanic activity
What causes seismic waves to form?
Energy released by earthquakes
What causes convection?
Differences in temperature and density
Which structural layer creates Earth’s magnetic field?
The liquid outer core
What is the difference between compositional and structural layers?
Compositional = what the layer is made of.
Structural = how the layer behaves physically.
Name two indirect methods we use to study Earth’s interior
Seismic waves, gravity measurements, meteorites, lab experiments
What type of wave cannot move through liquids?
S-waves
In which layer does rock convection occur?
The mantle (especially the asthenosphere).
Which metal is mainly responsible for generating Earth’s magnetic field?
Iron
Which structural layer is soft, hot, and able to flow: lithosphere or asthenosphere?
Asthenosphere
Why are meteorites useful for studying Earth’s composition?
They preserve materials from the early solar system similar to Earth’s original makeup
Why do P-waves and S-waves change speed as they move deeper into Earth?
They speed up or slow down based on density and state of matter.
Explain why cool mantle rock sinks and warm mantle rock rises.
Cooler rock is denser; warmer rock expands and becomes less dense.
How does the inner core help the outer core make the magnetic field?
The inner core’s heat powers convection in the outer core, which keeps the liquid metal moving and generating the field.
Name the discontinuity between the crust and the mantle.
The Mohorovičić Discontinuity (Moho)
Why is drilling limited for studying Earth’s deep interior?
Too hot, too much pressure, and too expensive to drill very deep
Describe the difference between how P-waves and S-waves move.
P-waves compress and expand (like a slinky). S-waves move material up and down (like a rope)
Why does convection in the outer core happen much faster than convection in the mantle?
The outer core is liquid metal, which moves easily, while the mantle is solid rock that flows very slowly.
Why is the motion of the outer core’s liquid iron necessary for keeping Earth’s magnetic field going?
Because the flowing metal constantly moves electric charges, which creates an electric current.
Explain why the outer core is liquid and the inner core is solid even though the inner core is hotter
The pressure in the inner core is so high that atoms cannot move freely, so iron solidifies despite high temperatures.
Explain how multiple types of evidence (seismic, gravity, labs, meteorites) work together to build Earth models
Each gives incomplete information, but combining them allows cross-checking and more accurate inferences
Why do seismic waves bend (refract) when they enter layers with different densities?
Because the change in material causes a change in wave speed, which forces the wave path to bend.
How does convection deep inside Earth affect the surface?
The rising and sinking of mantle material pushes and pulls on the tectonic plates, causing them to move.
If Earth’s magnetic field began weakening, what is one effect scientists might expect to see on Earth’s surface or near-Earth space?
More charged particles reaching Earth (stronger auroras, potential satellite or power grid issues) because the magnetic field would block less solar wind.