E4
Lesson Summary
Vocabulary Link
- Mohorovičić Discontinuity
- Moho
- Gutenberg discontinuity
- p wave shadow
- s wave shadow
- Early density calculations for the Earth indicated that the composition of the Earth’s interior was different from the composition of its surface.
- A travel-time delay in P waves from the same earthquake indicated the presence of a rigid layer of increased density below the Earth’s crust.
- The Mohorovičić Discontinuity, or Moho, marks the boundary between the crust and the mantle.
- The Moho indicates that oceanic crust has depths up to 10 kilometers (6 miles), while continental crust can have depths up to slightly in excess of 70 kilometers (43 miles).
- A P wave shadow was the first indicator of a central core in the Earth.
- An S wave shadow indicates that this core has a liquid component.
- The Gutenberg Discontinuity at 2,900 km ((approximately 1,800 miles)) marks the boundary between the mantle and the core.