The theory of plate tectonics explains how Earth's continents move. According to this theory, which of the following statements is FALSE? Earth's crust is composed of relatively thin, light plates that float atop the dense, viscous upper layer of the mantle. Ocean basins can grow along divergent boundaries, where the ocean floor splits and spreads apart. Continental plates have relatively stable shapes because they are heavier than oceanic plates and tend to sink below oceanic plates where the two types meet. Many of Earth's mountains resulted from the collision of two continental plates along a convergent boundary.