Earth's crust is made of the earth's crust and upper mantle. It is subdivided into portions called plates that move above the mantle. The two kinds of crust are oceanic crust, which is thinner but denser than continental crust. The earth's crust is made of plates moving slowly and interact in various ways in plate tectonics. The interaction of the plates produces earthquakes, mountains, volcanoes, and other geological features. Heat from the earth's interior makes the plates move above the mantle. This movement causes the formation of three types of plate boundaries, which are divergent boundary (two plates moving away from each other) and convergent boundary (plates moving towards each other). The three types of convergent boundaries are oceanic-continental convergent boundary, which forms volcanic island arcs, oceanic-oceanic convergent boundary forming continental volcanic arcs, and continental-continental convergent boundary wherein there is no volcanic activity.