Flexi Says: There are two processes occurring in the earth's crust, seafloor spreading and subduction. In seafloor spreading, the lava pushes the seafloor horizontally away from the ridge axis. In some places, the oceanic crust comes up to a continent. The moving crust pushes that continent away from the ridge axis as well. However, when oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate. This process, called subduction, occurs in the oceanic trenches, which balance the diameter and shape of the earth and keep it constant. The entire region is known as a subduction zone. Thus, the earth is not getting any bigger and wider.