In celebration of the new book, Cairns: Messengers in Stone, here is a guest post from the author, geologist (and good friend) David Williams. It’s a beautiful book–well-written, nicely designed, a delight to read and to give. Here’s David:
Most of us know the story of Hansel and Gretel: Evil stepmother brow beats milquetoast husband into abandoning kids in the forest but enterprising son leaves a trail to follow home. The first time Hansel uses stones, which works, but the second time he drops bread crumbs, which fails, and the duo almost gets eaten by a mean old nasty witch. Ultimately the kids survive but perhaps they wouldn’t have gotten into this situation if they had done what many experienced hikers do and built a cairn.
It wouldn’t have been hard. A cairn is simply a heap of stones. Neither size nor shape really matter. Most often used in this country for indicating a trail, cairns are also erected to mark a grave, serve as an alter or shrine, or reveal property boundaries or hunting grounds. Built across countries and cultures, cairns have been an effective means of communications for thousands of years.
With such an enduring history, you can imagine the pressure for building a good cairn. Just picking out the right stone can involve many considerations. A cairn made of river cobbles, with their well-rounded edges, will look and have to be built differently than one made of sandstone blocks, which often break into nice flat pieces. Basalt and granite offer a third style, with their jagged, rough surfaces that often interlock well and allow one to build a large and very stable cairn.
Once you have your rocks, you need to choose the right spot. Think of a cairn as Madonna or Lady Gaga; it wants to be seen and noticed, so don’t hide your cairns where no one can see them.
Now you have to start to pile up your heap and like many things in life, with a good base the rest will follow. Start with big rocks, preferably tilted slightly toward the center, so that when they settle gravity will help lock the stones in place. You may also want to work with differently-sized rocks, which can also guarantee a stable, pleasing, and downright handsome cairn well worth the hours you spent on building it.
Your work is not done yet. As the cairn rises, you must ensure that every stone has at least three points of contact, which prevents unseemly and destabilizing stone wiggle. All joints must overlap, or bridge each other, too. Finally comes the capstone. “Well, obviously one big stone rather that lots of wee ones,” writes folk musician and cairn-builder Dave Goulder.
One final consideration. Should you even build a cairn? From a ecological point of view cairns can provide habitat for a variety of species but you should be aware when acquiring rocks for your cairn. That rock might provide a protected haven for ground dwellers such as rodents, reptiles, or insects. It might also create ideal habitat for plants and lichens. And, if you have to walk off trail to get a rock for your cairn, you might be doing more damage to fragile ecosystems. There are also cultural and esthetic concerns. The rocks and/or the landscape may be sacred to native people. And in national parks from Acadia to Yosemite, there has been an epidemic of cairns with vast cities of cairns being erected in the backcountry. Some might feel this is a way to connect to nature. Some may find these spots to be offensive rock grafitti and not respectful of the wilderness experience. So no pressure.