To the Bone Caves and beyond

May 26th 2019

Some days out take an unexpected turn, as on 6thApril 2019.  Gordon Rothero was up for a spring visit, and had wanted to check out some of the uncommon mosses that occur along the Allt nan Uamh (Bone Cave Valley), south of Inchnadamph (NC2517).  Gwen Richards and I accompanied him, with Jess, on a day that was intermittently sunny, but with a chilly breeze.  We left the car-park with a greenshank Tringa nebularia calling just across the road and saw our first dipper Cinclus cinclus shortly afterwards.  First stop was just above the site of the former hatchery, where Gordon located broad-leaved brook-moss Hygrohypnum duriusculum, growing on rocks in the watercourse (photo 1), at probably its northernmost site in the British Isles.

The well-built path beside the first falls gave us colt’s-foot flowering beside a small tributary (photo 2), reminding us of the natural waterside habitat of this species, which often occurs as a ‘weed’.  A pine marten had left a territorial marker in the form of a scat not much further on.  Half a kilometre upstream we found a sheltered spot for coffee below a lone rowan on the second set of falls, after which Gordon continued his bryological browsing (photo 3).

Just to the east of these falls is the impressive rising of Fuaran Allt nan Uamh (photo 4), one of several places where underground water from further up the valley reaches the surface.  Shortly afterwards, Gordon set about re-finding the tiny plants of the short-tooth hump-moss Amblyodon dealbatus in a limy flush where he had first recorded it back in 1992. This proved more challenging since its distinctive capsules were well past their best, but he was successful (photo 5).  It is a northern plant of base-rich montane flushes and damp turf in dune slacks.

As we walked up the valley, we passed and admired a second substantial rising, known to cavers as the Elephant Trap, which, following some wet weather, was brimming over (photo 6).  Lunch was taken on the south side of the valley below the Bone Caves, in the sun and out of the freshening and gusty wind.  Gordon’s next objective was a large limestone boulder just up the slope, where he hoped to re-find another tiny species, the alpine extinguisher-moss Encalypta alpina, where he had first recorded it at its isolated northernmost site in the British Isles.  He was not so fortunate this time, since the wind had dried out the crevice in which it had occurred and it was not to be seen.  A tiny pinkish lichen, Dimerella lutea, growing on moss in another crevice, caught Gwen’s eye (photo 7),but that was small compensation.

Shortly afterwards she and I entered what was, for us, terra incognita.  Gordon had been taken many years before, by a caving friend, to a large pothole about 500m up the dry valley which runs south from the eastern end of the loop in the Bone Cave path.  We found it without difficulty, rimmed at its northern end by a 5m high limestone crag (photos 8 and 9), at the foot of which was a vertical shaft with scaffold poles across it to facilitate entry.  We decided against any heroics, not having the time, kit, and, in my case, inclination, to explore it further.

However we did list the pothole, logging over 40 species of higher plants, including some impressively large clumps of holly fern in a secondary shaft inaccessible to deer (photo 10).  Gordon also recorded about the same number of bryophytes, including the blunt-leaved tufa-moss Gymnostomum calcareum, an uncommon species of damp, shaded limestone.

We did not fully realise, until we had returned and consulted Caves of Assynt (T.J.Lawson ed., 1988), that what we had been looking at was the original entrance to the famous Uamh an Claonaite (cave of the sloping rock), the longest cave system in Scotland.  It has been actively explored by cavers since the 1960s and is now known to extend underground for well over 2km, with some eight or more challenging water-filled sumps, culminating in a huge chamber known as the Great Northern Time Machine, situated just behind and below the Bone Caves.

This cave system has yielded remains of three brown bears that have been dated at 11,600, 26,000 and 45,000 years BP.  I am still searching for a full account of its exploration, but meantime append two illustrations from a fascinating talk on the Inchnadamph Bone Caves to the Field Club given by Peter Dowswell of the Grampian Spelaeological Group on 19thNovember 2015.  They show a plan view of the whole cave system (photo 11) and the brown bear skull dated at 11,600 years BP (photo 12).

After which excitement, our return along the narrow and quite exposed path that accesses the Bone Caves (photo 13) was hardly adventurous but, with the wind gusting vigorously, quite sufficiently challenging, at least for the oldest member of the party.  We drove back for a welcome cup of tea in Gwen’s warm conservatory and rounded off the day with fish and chips down by the harbour in Lochinver.

Thanks to Gordon Rothero for on-line updates on Uamh an Claonaite, Alex Scott for access to caving literature and Peter Dowswell for the use of illustrations from his talk.

Ian M. Evans

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