1.   The heavy oceanic lithosphere descends into the mantle, beneath the lighter continental lithosphere.

2.   Continental lithosphere stands higher than oceanic lithosphere because continental crust is both of greater thickness and lower density than oceanic crust.

3.   This kind of behaviour, known as flexural isostasy, is especially important for oceanic lithosphere and for thick continental lithosphere with a high rigidity.

4.   By contrast continental lithosphere has a significantly lower mean density than oceanic lithosphere and its buoyancy with respect to the asthenosphere prevents all but limited subduction.

5.   Transform boundaries, marked by transform faults, occur both as fracture zones along mid-oceanic ridges and as strike-slip fault zones within continental lithosphere.

6.   The west coast of South America provides an example of oceanic lithosphere subduction beneath continental lithosphere.