Sand: A sound created by human footsteps along a shoreline of wet, coarsely ground stone; a shore of sound created by humans walking in such a space; by inference, the grains of  stone that sing  ‘sand’ when shifting under the weight of a human in motion. Neither shore nor human, “sand” is both at once: the sound of a human passing along a shore.

I walked along the sand at the edge of the tide.

Lake Shore

It will become “sand” when a human walks across it.