Once upon a time, before global positioning systems, maps, compasses and bread crumbs, trekkers still had to find their way from point A to point B.
That's no great problem on a worn footpath replete with wooden bridges over brooks, yellow brick roads and signage.
But what happens when the destination is at an altitude at or near tree line? When obvious footpaths disappear into scattered collections of gravel and scree? When the navigational hints of an occasional juniper tree or a patch of manzanita give way to a long stretch of smooth granite and there's no clue about the most direct or least risky potential switchback?
If you've hiked much in the Sierra, you've been there, done that. For those uneasy with a map and compass, there are times when you're awfully glad somebody came to that spot before you and left a cone-shaped pile of rocks called a cairn.
Cairns are found throughout the world and throughout history. The higher, rockier and more featureless the terrain, the more likely you are to find them on trails.
Some, like those at Dartmoor in England, have spurred debate about their origin and significance in the region near Plymouth, located just above the English Channel. Archaeologists posit that beyond their navigational purpose dating back to the Bronze Age, they could have been war memorials as well (www.legendary dartmoor.co.uk/ cairns_ moor.htm).
If you hop on the Internet and Google "cairn imagery," you'll see some very stout and artistic examples around the world. Otherwise known as "ducks," these mini-pyramid rock piles like dots you connect along the way can signal that you're on the right path.
Overzealous cairn-builders have been known to create so many routes along a stretch that, well, they are the opposite of helpful.
"That's confusing," says Leon Nelson, 74, an avid hiker who specializes in the Trinity Alps to the north in California. A retired Redding dentist, he's been backpacking for 60 years.
"I'd say I spend at least 30 days a year out there backpacking I've hiked every one of the lakes in the Trinity Alps." (He says there are 256.)
His point is that cairns or ducks can serve a valuable purpose.
"On occasion, I find they're extremely helpful. It permits off-trail travel," he says.
If one wants to explore off the beaten path, a system of cairns will come in handy at the end of the exploration and allow the hiker to connect the dots back to the designated trail.
However, Nelson says, hikers who mark such a route should disassemble it on the way back.
With a few exceptions.
When a hike takes you above the tree line along a smooth, rocky surface at a place where you really can't tell where others have hiked before you the cairn can serve you well.
"Anything at tree line and above and on hard surfaces" would be an acceptable place for semipermanent cairns, Nelson says.
Unless you're in a federally designated wilderness area. That's where many duck the issue of cairns.
Nearly 45 years ago (Sept. 3, 1964), Congress gave birth to the Wilderness Act. Therein, precisely at Section 2, subsection (c), a wilderness is defined as "in contrast with those areas where man and his own works dominate the landscape, is hereby recognized as an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain," an undeveloped area "without permanent improvements."
You could argue that cairns violate the act when constructed within a federally designated wilderness area such as the Desolation Wilderness in the nearby Eldorado National Forest.
If there is a specific reference in U.S. Forest Service policy forbidding the construction of cairns, Frank Mosbacher is hard-pressed to find it.
He's the public information officer for the Eldorado National Forest, which has 600,000 acres including about 100,000 acres combined in the Desolation Wilderness at the north end and the Mokelumne Wilderness at the south end.
Both of those wilderness areas are subject to the high ethical standards of the Wilderness Act, he says, as well as the general leave-no-trace policy of the Forest Service.
"In the wilderness, the general rule is, leave no impact. If you're marking trails, that's outside the wilderness ethic," he says.
He stopped short of saying cairn building is the No. 1 crime of the century, and he didn't suppose that hikers are cited often for constructing rock piles that will help the next hiker. (Now, cutting down or defacing trees will really cook your duck, or goose.)
"But people going into wilderness areas are expected to know how to use map and compass," he says.
If that were the case, scattering rock edifices like bread crumbs would be unnecessary. And, of course, as Nelson pointed out and Mosbacher agrees, the cairns "may not be taking you where you want to go. They might be leading you to a favorite campsite or area."
That's why, when Forest Service rangers encounter cairns, they're going to disassemble them, Mosbacher says, and bring back as much of the natural order in the forest as possible.
Mosbacher is realistic, though. He knows there are places in Desolation where you can hear car traffic on Highway 50 and "Desolation has pretty good cell phone coverage."
So, when you could literally make reservations for a casino weekend or Twitter from the trail, how can a cairn, a well-meaning navigational ritual, be such a defilement to wilderness areas?
Countless hikers upon returning from the gurgling spectacle of Horsetail Falls above Highway 50 in El Dorado County are happy to see cairn markers as they descend. And, yes, the falls are located within the federally protected Desolation Wilderness (where Horsetail is situated).
There's the tradeoff: human footprint the man-made cairns for practicality.
Walk among the rocks
Here are two nice hikes in Eldorado National Forest. You'll see cairns along the way as you navigate.
What: Shealor Lakes
Where: Amador County, about five miles east (on the left) of the junction of the Mormon Emigrant Trail (Highway 5) and Highway 88. It's at the southern edge of the Eldorado National Forest, just across the road from Silver Lake. Free parking. No bathroom facilities.
Distance/elevation: Just under three miles round-trip with a 750-foot elevation gain. The trip in, to the two pretty lakes, is mostly downhill. The return, with some stout ups, will burn some calories. Though you're at 7,000 to 8,000 feet elevation, it's doable by kids and in-shape adults. The cairns on the mostly treeless portions are very helpful.
What: Horsetail Falls
Where: El Dorado County, along Highway 50 at Twin Bridges, two miles east of Strawberry. Parking is $5. A portion of the hike is within the boundaries of the Desolation Wilderness.
Distance/elevation: Less than three miles round-trip with a 500-foot elevation gain. The payoff is a front-row seat of the falls in whatever state they are in (spectacular in the spring). You'll top off at around 6,500 feet and share much of the journey with a gurgling creek. The falls guide you to the top. Most of the cairns you'll encounter will be on the return downside.