Approximate trace of the San  Andreas fault system.	Aerial view of part of the San  Andreas fault trace near LA.	Ground view of the San Andreas fault.

A third type of plate boundary occurs when two plates slide past each other, rather than coming together or moving apart. In such a boundary, lithospheric material is neither created nor destroyed. Called transform boundaries, they are characterized by large faults, transform faults, and associated shallow focus earthquakes. In the US the best known transform boundary is the San Andreas fault that separates coastal California, (a part of the Pacific Plate) and the remainder mainland part of the state which is attached to the westward moving North American plate.