In praise of ducks

No, not our fine feathered floating friends, praiseworthy though they be... I mean those little piles of rocks (cairns to many) that mark your way along a trail. Most ducks are humble things, a couple of flat stones stacked in a visible spot. Of course, we know from Andy Goldsworthy and countless anonymous predecessors that a cairn can be a lovely, deliberate thing, but the typical trail duck is a utilitarian object, and it seems that the most haphazard, ungainly, and precarious are often the most visually pleasing. Placement is everything with a duck... the whole point is to guide you in the right direction from an ambiguous fork or a boulder-strewn section of trail, so the duck must be fairly obvious just past the point of confusion. Ducks are also a nice example of spontaneous, anonymous human cooperation.