The centrepiece of the garden is undoubtedly the complex of sinuous waveforms created by the Snail Mound, the Snake Mound and their related lakes. Jencks writes:

Curved and counter-curved shapes are structural and often found in nature, for instance in the meander of a river. Waveforms underlie so many natural activities: sea waves, of course, and sand forms left by the incessant waves on the ocean beach; the vortices caused by pulling a solid object through stationary liquid; the swirls of air currents where warm and cold air meet; and the rock curls evident in mountains, a result of a long, slow geological process of movement.

from: http://gerryco23.wordpress.com/2011/05/03/the-garden-of-cosmic-speculation/