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Geology Chapter 2
Terms in this set (26)
1 - Orbiting the SUn
2 - Large enough to be spherical
3 - Has cleared its own orbit of other large bodies
What was the Earth's atmosphere composed of before life evolved?
Mostly CO2, H2O, SO2 and N2
When did unicellular plants first appear on Earth?
2 Billion years ago
The atmosphere was mostly like it is now, when the first land animals appeared. When was that?
370 million years ago
What is the density of rocks at the Earth's surface
What is the average density of the Earth?
How do we find out the mass of the Earth?
F = GmM/r^2 = ma solve for M.
We sent up LAGEOS satellites to check
What is LAGEOS
The Satellites that we sent up to measure the mass of the Earth. They are brass balls 60cm in diameter. Covered in reflectors. They look like golf balls
Speed of seismic waves in lower density
Speed of seismic waves in higher density
Speed of seismic waves in higly rigid rock?
Speed of seismic waves in less rigid rocks
How does the speed of seismic waves vary with depth in the Earth's surface?
Speed increases because the rigidity of the rocks increases due to pressure.
At what depth does the mantle become the core?
Is the core more or less dense than the mantle?
Do seismic waves travel faster in the core or the mantle and why?
Faster in the mantle because it is LESS dense. (remember speed of seismic waves DECREASES with density)
Name the two types of seismic waves
1 - P-Waves (comPression waves)
2 -S- Waves (Shearing waves)
What depth beneath the continental and oceanic crust is the Mohorovicic Discontinuity?
30km beneath Continental
10km below oceanic
What speed do P-waves jump to in the Moho
The Moho is the boundary between which two parts of the Earth?
The crust and the mantle
Which is more dense, continental or oceanic crust?
Which is richer in Silica (SiO2), the crust or the mantle?
The Crust (remember that's where you find sand)
The rigid uppermost part of the mantle and the crust
The weaker layer just below the lithosphere.
Which three elements undergo radioactive decay, providing heating, mostly in the crust?
What is the average rate of heat loss per m^2 on Earth?