Answer:
Silicon, Magnesium and Aluminum
Explanation:
The continental crust is formed essentially of alumina silicates (hence it was formerly called sial) and has an overall composition similar to that of granite. It is 25 to 50 km thick and the primary seismic waves propagate at 5.5 km / s.
The oceanic crust is composed essentially of basalt, formed by magnesian silicates (hence formerly called sima). It is 5 to 10 km thick and is denser than the continental crust because it contains more iron.
