The Cairn on the Slickrock

The cairn on the slickrock stands about knee-high, a stack of flat sandstone chips narrowing as it rises. It sits on an open slope of bare stone in Arches National Park, on the trail to Delicate Arch, where the route crosses slickrock that will not hold a footprint. The cairn is the same red sandstone as the rock under it, fine-grained, with a desert varnish on the top stones that turns nearly black in morning shade.

It marks the trail because the trail cannot mark itself. Boots do not leave lasting prints on sandstone, and a route across a long stretch of bare slope is invisible except where the cairns stand. Each cairn is set within sight of the next, a small upright shape in a field of otherwise unbroken rock. The line of stones is the trail. A cairn is read at a glance; a misplaced one would be worse than none. Cairns take the shape of a person standing at a distance, which is why the eye finds them so quickly on open stone.

The cairn was built the way stone cairns are built in the desert West, one flat chip chosen to fit the one beneath it, set by hand, balanced, then fitted with the next. The flatness is the whole trick of it; a round stone would never hold. The gaps between the stones let the wind pass through instead of piling up against the stack. The stack narrows as it goes up, so a wind from any direction finds less and less to push against. A gap between two middle stones holds a pinch of sand that rain brought and wind has not carried off.

The rule that keeps the cairn honest is that no one adds to it. Visitors are asked to leave the stones where they are. One added rock turns a trail marker into an ornament; the shape of a cairn changes, and a changed shape cannot be trusted. It is only the untouched ones that can be believed. Beside the route, other small piles appear from time to time, stones stacked for the balance of it; the park's instruction covers them too. A stone set down in play looks exactly like a stone set down in need. They are not trail. The true cairn is the one that stands where the trail needs it, and the others stand where someone stopped.

The cairn is a thing the weather has worked on. Heat expands the stone through summer afternoons; cold contracts it on winter nights. Rain darkens the lower rocks and dries them lighter. Wind has driven grit against the edges of the smaller chips until they are rounded, and the desert varnish is worn through in a patch on the windward side of the top stone. The windward side of the lower stones is paler than the sheltered side. On bright days the cairn throws a short shadow that moves around its base as the sun crosses; on cloudy days it goes flat against the rock. Hikers who stop beside it do not add a stone; the rule has made it a thing to look at.

The top stone is a palm-sized chip of the same sandstone, its varnish scuffed along one edge. It leans slightly toward the southwest, its far corner chipped clean away.

Arches National Park

Photos: Ken Lund (CC BY-SA 2.0)