The Earth's Crust
The boundary between crust and mantle - Moho Discontinuity - boundary defined by a contrast in seismic velocity.
Crust - less than 1% Earth's volume.
5km-10km thick - composed of basalt, gabbro and diabase. Relatively simple, composed mainly of mafic rocks (basalt) or sima (silicates). Thinner and less complex.
Denisty - 3.3grams per cubic centimetre.
More dense than continental.
Oldest - 200million years old.
30km-50km thick - reaches 70km in places.
Composed of less…