Hidden in a limestone valley about 20 minutes from Ullapool are a series of remarkable, prehistoric caves. The openings are part way up one side of a partially, hidden and steep heather covered hillside. They can be easily seen and reached by following the well-worn, rough track that begins at a car park on the A837 and gradually weaves its way along the banks of the River of the Caves.
It’s hard to imagine it now but valleys like this used to be far more lush and fertile and were well able to keep a family fed and watered. Deer roamed the forest, berries flourished on the hills and salmon and trout swam in the rivers.
The arrival of sheep just over 150 years ago destroyed much of the original natural habitat as they nibbled any young tree saplings before they had barely taken a foothold in the peaty soil. The landowners, convinced that sheep would bring in more income than the crofters, cleared the land - both of people and much of the native woodland. While what remains is beautiful, the land has never recovered from the onslaught of sheep.
In the river valley there is evidence of an ruined shielding (where crofters lived during the summer months tending their cattle) as well as a old water powered flour mill by the riverside. That reveals that crops of barley and oats were once grown locally - hard now to visualise in such a dramatic and sparsely populated landscape where not much now grows except bracken, heather, deer grass and rowan.
This area was once also home to wild creatures that are now extinct in this part of the world: bear, wolf, lemming, reindeer and lynx all prowled these hills. These animals were common across what used to be the landmass of Laurentia, a continental plate that also included North America and Greenland. The reason we know that is that the caves found in the valley contained large numbers of the bones of these animals and more. Amazing how massive geological shifts influence not only the geology but also the ecology of an area.
The Bone Caves are here because during the wetter and warmer periods of the ice age, groundwater dissolved away the limestone that dominates the hills of this part of the world to create a system of underground caves and narrow passages. Some of these now dry caves may have provided a refuge for animals and possibly even humans. Huge numbers of bones of a wide variety of animals and birds have been discovered in the deeper recesses of some of these caves including brown bear, arctic fox, Northern lynx, arctic lemming, otter and wolf.
By far the most numerous bones are from reindeer which have been dated to between 9,000 and 44,000 years before the present. There are two theories as to why so many reindeer antlers ended up in the caves: the first is that this was due to human’s hunting them and then discarding the antlers or using them as tools. The other (and seemingly more plausible) is that the antlers were washed down and through the underground passages after being discarded by female deer using the nearby calving grounds (these are still popular with red deer in the local area showing how such places endure). Female deer drop their antlers shortly after bearing a calf and also nibble the ends to absorb much needed calcium which would explain why so many of those found looked to have worn tips.
The caves were originally explored by two Victorian geologists - Benjamin Peach and John Horne - who were more interested in the geological story they could tell than the archaeological. It’s still remarkable that such things were found at all.
The other astonishing thing about this valley is the river and the natural springs that exist along its route. Natural springs are a result of the underground caves and passages. There are a series of sink holes along the banks of the river that come to life after heavy rains. Given the recent immense storms there has been an incredible amount of water running off the hills. At parts this overran the usual river banks and flowed onto the surrounding grass. In one particular sink hole, gravel was being bubbled up as water percolated upwards. In another, bubbles could be seen ever gently rising to the surface.
As we climbed up the valley, the full, fast and furiously running river suddenly disappeared leaving a dry riverbed of rocks. This part of the river only runs in winter as the rest is diverted into the underground passages. After seeing so much water further down it was rather eerie for it suddenly to stop. The valley was silent.
We made our way up the steep track to the first cave where we stopped for lunch. Between two of the caves was a hole just big enough for a child or small adult to wriggle through. Water dripped from the peat banks above each cave entrance creating a curtain of rain during wet weather. You could imagine ancient ancestors taking shelter in these caves and huddling together to keep dry and warm.
After visiting all four caves we headed back down the track watching dippers flit between boulders and rocks. The three hours we had spent visiting the caves had actually allowed us to travel through time thousands if not millions of years. Amazing.
(With thanks to Roz Summers, a Highland Council Ranger, for a great tour of the caves.)