Back to the proper business of Scottish Nature Boy…
On Sunday, to do something special for our little dog Ella’s fifth birthday, we drove out to Callendar, a gateway town for the Loch Lomond and Trossachs National Park (Scotland’s first National Park), to visit the Bracklinn Falls, a popular tourist spot since Victorian times, when Callander itself became a favoured destination for early tourist visitors to the Trossachs, much loved by Queen Victoria, and popularized by Sir Walter Scott and the Romantic movement. The name is thought to derive from the Gaelic words “breac” – speckled or tawny, possibly referring to the colour of the water of the Keltie Burn which flows over the falls, and “linn”, a narrow river gorge.
A fortuitous wrong turn walking out of the visitor car park took us up the hill behind Callander where we came upon a great view of the south face of Stuc a’Chroin (Gaelic: peak of harm or danger), at 975m, one of the southern Munros (Munro number M176) visible from the Forth Valley.
We also found this old Observer Corps bunker (according to a local dog walker), a World War II relic, complete with its original ventilation structures. Probably quite a quiet wartime posting, methinks?
Back on track, the footpath out to Bracklinn Falls runs along the edge of both native woodland (oak and birch) and mature non-native sitka fir plantation. Reflecting the high rainfall and lack of any significant air pollution in this part of Scotland, both the native and sitka trees and woodlands are fairly festooned with so-called lower plants: ferns, lichens, mosses, liverworts and algae.
Scotland, particularly the western highlands and the coastal temperate rainforests of Argyll, away to the west and north-west of Callander, is particularly rich in these groups of plants, being something of a global biodiversity hotspot for them. I am involved in steering a partnership project with Plantlife Scotland to promote awareness, understanding, identification and better management for habitats supporting these plant communities. You can find out more about the project and see all the great materials it is producing
here. The cool humid conditions in and around waterfalls and their gorges are ideal for a wide range of these lower plants. And so it is around Bracklinn Falls too.
And what falls these are, although not so much for the actual waterfalls themselves. Admittedly, when the Keltie Burn is in flood or in spate, the falls are pretty spectacular (and the river here actually washed away the footbridge crossing for the falls in 2005). At the moment, however, following the recent weeks of frosty conditions locking up the groundwater, and very little precipitation (much of which is still on the hills upstream as snow), the river’s level is quite low and the waterfalls relatively quiet. But the geology and structure of the falls is pretty amazing.
As you can see from these pictures, the sandstone formations around the falls look like a spillage of great building bricks from a giant’s toy box. The massive square-ish blocks of red sandstone have broad veins of a much softer aggregate, a pudding stone, running through them which have been preferentially eroded away by the water’s steady, relentless efforts. Every litre of water will carry away a few molecules of rock surface, ongoing over millennia, combined with the periodic wearing, grinding, chipping, sanding effects of boulders, pebbles, sand and silt hammered against rock faces during floods, to create an eroded route of least resistance through the gorge, an ultra-slow motion carving out of a stone-washed aquaduct.
These great geometric geological formations induce in the visitor a sense of being somewhat diminished in size, like an ant in a box of Lego – Honey, I shrunk the tourists… The process of erosion continues today. In the following picture, the slow process of leaning over and collapse of these vertical bedding planes in the sandstone due to the undermining effects of erosion put me in mind of sliced bread tipping out of its bag. Notice the heavy growth of mosses on the horizontal slab.
This swirlhole or pot hole in the rock was created by repeated erosive swirling by the river of small stones in a depression in the bedrock, eventually forming this little hole. That fact that it is now about 20 metres downstream of the waterfall that used to fow over this edge and some four metres above the water surface illustrates that waterfalls move slowly upstream with time as they erode into the rock face, and that the river once flowed over this surface, however many years ago it took for the water to carve the adjacent gorge.
As well as the good habitat conditions for lower plant species, Bracklinn Falls also supports dippers, although we didn’t see any yesterday. Dippers (scientific name Cinclus cinclus), those little brown and white birds of Scottish gravel-bed rivers, were badly affected from the 1970's onwards by the acidification of Scotland’s rivers, which affected the little river invertebrates on which the dippers feed with their underwater foraging habits (walking upstream on the river bed, the water current on its sloping back helping to keep it underwater), and they became less common or even disappeared from acidified rivers.
Dipper painting by Raymond Harris Ching (from "AA Book of Birds", 1969)
Dippers are, however, likely to have made a bit of a comeback in recent years, at least in Scotland, as those acidification problems have slowly resolved following tighter legal controls over emissions of sulphur dioxide and other acidifying substances from industry in the past three decades. The presence of dippers is a good indicator of a healthy gravel-bed river ecology and the Keltie Burn and Bracklinn Falls are usually good places to spot them flying up and down the river, or bobbing up and down on favoured boulders in the river. A treat at any time!
