“In reality, a river's basic shape... is not a line but a tree. A river is, in its essence, a thing that branches... Although it flows inward toward its trunk, in geological time it grew, and continues to grow, outward, like an organism, from its ocean outlet to its many headwaters. In the vernacular of a new science, it is fractal, its structure echoing itself on all scales, from river to stream to brook to creek to rivulet, branches too small to name and too many to count.”