The above animation shows the simulated evolution over geologic timescales of a watershed and its drainage network. The white area at the outset of the simulation denotes the region that is to become the watershed. The outlet of the watershed is shown in bottom-center of the animation. As time progresses the river network evolves and extends into the watershed. The mechanisms of watershed growth include both a fluvial transport term which is strong within the drainage network and a diffusive transport term which is strong on the hillslopes (white areas). The erosion (both fluvial and diffusive) is ultimately balanced by an uplift component which is driving the evolution. When balance is reached the watershed is said to be in dynamic equilibrium with its surroundings. The final snapshot roughly corresponds to this condition.