I am always amazed by how few outdoor enthusiasts know the true origin of cairns. I feel it is really important that this information is out there as it highlights why we shouldn't be adding to, damaging or building new cairns, as this will only confuse any much needed research on the subject.
When out walking with clients, other instructors or friends I often recount this fascinating history and rarely does anyone have any previous knowledge of their origins. If asked ‘where do cairns come from?’ replies often range from walkers built them, shepherds used them to mark their way or Julia Bradbury built them all!
But the true origin goes back to late Jurassic era and a dinosaur called the Mythosaurus - a Sauropod (large herbivores that walked mostly on four legs) - that closely resembled the Diplodocus but with a much bigger head and shorter wider neck. The Mythosaurus was a placid animal that lived in large herds and fed on vegetation such as trees and large shrubs, but because of their small soft teeth they needed a little help to enable them to digest the tonnes of vegetation required for them to survive. In a way similar to what chickens do now, the Mythosaurus ate small rocks which then sat in their stomach and helped grind up whatever had been eaten. They were very large animals (25-30m long as adults) so hardly noticed the extra weight but would stay in the valleys and avoid marshes in case they sank.
When a Mythosaur was old and nearing the end of its long life, in an effort not to be a burden, the dying animal would leave the herd for the last time and take itself off to die. It is not known why but each dying animal is thought to have headed to the highest point around and sit on the summit whilst waiting for its inevitable death. Maybe it was so that they could enjoy the view, look over their territory or keep an eye on the herd - who knows?
After death the body would slowly begin to rot away, first the skin, flesh and insides would disappear leaving only the skeleton, displaying the huge ribcage containing the rocks from the stomach. Eventually the bones would crumble and turn to dust leaving only the rocks behind in a nice neat pile on top of the mountain. And that Prentice is where Cairns come from.
If you have a Cairn that you really want to get to, maybe we can help. Please contact Freestone Climbing for more information.