the four separate processes (volcanism, impact cratering, erosion and tectonics) listed below can also be interrelated, so although one may be most important to a particular feature, others often also play a role. for example, some erosion has occurred on the volcanic island of hawaii, there are impact craters on the slopes of olympus mons, and volcanism and tectonics almost always go hand-in-hand. the earth's grand canyon is an example of .