What is the moho and what is it made of?
The Moho or Mohorovicic Discontinuity is a boundary that separates the crust from the upper mantle. The crustal rock above and the mantle rock below are different rocks based on silicate minerals.
The Mohorovicic Discontinuity was discovered by Andrija Mohorovicic, a Croatian scientist, in 1909 using seismic wave measurements.
The mantle rock allows the waves to travel faster than the rock in the crust, causing the seismic waves to refract at the boundary. Mohorovicic detected the refracted waves, which eventually return to the crust because of the round shape of the Earth, along with waves that traveled a shorter distance, but more slowly, directly through the crust.
Scientists have matched the different speeds of the seimic waves with different silicate rocks which are now identified with the crust and the upper mantle.
For more about the Moho, read here: