Earth Science
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What are the two types of crust?
Oceanic Crust (10 km) Continental Crust (20-60km) The oceanic crust is the ocean floor, and the continental crust is where we live
What layer is below the crust?
The mantle (2885 km)
What layer is below the mantle?
The outer core (2270 km)
What is the inner most layer?
The inner core
What are the 4 layers of the earth?
crust, mantle, outer core, and inner core
What are the two types of seismic waves?
body waves and surface waves
During an earthquake, energy is released within the Earth’s interior and travels to the Earth’s surface in the form of ___________.
seismic waves
What is ther difference between body waves and surface waves (the two types of seismic waves)?
Body wave travel through Earth’s interior and surface waves travel on Earth’s surface.
What two ways are body waves classified?
As primary waves (P-waves) or secondary waves (S-waves)
Which waves are the fastest (P-waves) or (S-waves)?
P-waves primary waves
What type of material can p-waves travel through?
p-waves can travel through any type of material; solid granite, magma, water, or air
What type of material can s-waves travel through?
s-waves can only travel through solids a way to remember this might be that s-waves start with s like solids
Which waves reach the seismograph first?
p-waves
What do p-waves do to the crust?
p-waves compress and expand the crust, similar to a spring They squeeze and unsqueeze the Earth materials
What do s-waves do to the crust?
they cause the crust to oscillate up and down and side to side
What are the two types of surface waves?
Rayleigh waves and Love waves They are the last to register on a seismograph Rayleigh moves in an up and down motion Love moves in a side to side motion
How do seismic waves show that the Earth has layers?
Seismic waves change speeds based on the material they are travelling through. On a seismograph this change can be seen during an Earthquake. The different speeds can help us infer the materials of each layer of the Earth.
How did they infer that the outer portion of the core is liquid?
S-waves are unable to pass through the core. Because we know that s-waves cannot travel through liquid we can infer that the outer core is liquid.
How do we know the inner core is solid?
As the p-waves travel through the outer core, there is a place that they get faster. Waves travel faster through solids, so we can infer the inner most layer is solid.
What is the core composed of?
iron and nickel About 85% iron and 15% nickel We know that the core is composed of metal because the Earth has magnetic fields. The crust and mantle are formed from rock, which is not metal, so they can’t cause magnetic fields.
Why is the iron and nickel, found in the core, solid in the inner core and liquid in the outer core?
The inner core has more pressure from the weight of the Earth keeping the iron and nickel from turning to liquid. The temperature inside both cores is 4300 degrees C.
What is the temperature inside the core of the Earth?
4300 degrees Celsius
What is the matle composed of?
iron-rich silicate rocks This layer is hot
How is the mantle subdivided?
Into the upper mantel and lower mantel The lower part of the upper mantle is called the asthenosphere (astheno means weak, but it was called that because it flowed). The upper part of the upper mantle is called the lithosphere (litho means rock or stone). It is is 100km thick.