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Shadow
zonesthe Earth’s
Investigating
Interior
Ian Sanders
Department of Geology
TCD
ASTI conference
3rd October 2009
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Shadow
zonesthe Earth’s
Investigating
Interior
Evidence for what’s inside
1. Average density
2. Seismic waves
3. Meteorites
4. Magnetic field
5. Experiments on making basalt
Mohorovicic discovered the Earth’s
crust exactly 100 years ago, in 1909.
The crust is about
30 km thick in most
places, but double
t
this under mountain
ranges.
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Shadow zones
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Ida and Dactyl
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Shadow
zonesthe Earth’s
Investigating
Interior
Evidence for what’s inside
1. Average density
2. Seismic waves
3. Meteorites
4. Magnetic field
5. Experiments on making basalt
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Sep 29 2009 - ended here
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Ratio of lead to uranium in zircon
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0.8
0.6
0.4
0.2
0
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Age of zircon in millions of years
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Shadow zones
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