Compositional layers: crust, ocean crust, thin, heavy, mafic; continental crust, thick, lightweight, roughly granitic; Moho; mantle, ultra-mafic
Mechanical layers:
lithosphere - outer layer, makes
plates, hard, rigid, rocky; asthenosphere - underneath,
hot, soft, mushy, allows plates to move
Why are two different systems used to define the outer layers of the Earth? Describe the two systems.
Describe the two types of crust and how they affect the appearance of the Earth and how they affect plate tectonics.
Compare and contrast the lithosphere and the asthenosphere.