Nic had booked onto a dusk wildlife watching event in Rothiemurchus forest from 21.00 hrs lasting 2 to 3 hours, which meant she could drop me off at the Cairngorm mountain carpark and I could spend an afternoon and evening up on the plateau of the central Cairngorms massif and then walk off at dusk to be picked up. I started out from the Cairngorm mountain car park at about 14.00 hrs taking the path up onto the plateau west of Coire an Lochan.
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| Ptarmigan |
On the walk up I encountered two workers repairing the excellent path from the carpark and stopped to give some positive comments on their workmanship, they seemed genuinely surprised and happy their efforts were appreciated by someone. A while later I too was soon genuinely surprised to walk straight past a pair of Ptarmigan by the side of the path in low cloud and more surprised that I managed to take a photograph, my usual attempt at wildlife photography are best described as abject failure. There were a visible and audible number of Ptarmigan that had congregated that afternoon in Coire an Lochain and chatting to a couple descending from bagging Ben Macdui, it seems that Golden Eagles shy away from popular walking areas and Ptarmigan take refuge in these safe havens.
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| Granite exposure in the headwall of Coire an Lochain |
Coire an Lochain has been formed by glacial ice quarrying into plateau and has exposed the geological structure of the Cairngorm granite in the headwall which cuts into the summit dome of Cairn Lochan. Primary vertical joints are attributed to cooling and secondary joints that parallel the surface topography are attributed to exfoliation., the exfoliation joints can be seen to increase in thickness with depth.
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| The lochans in Coire an Lochain |
On the corrie floor were three small lochs, one of which was holding a quantity of snow, recently avalanched off The Great Slab. On the sides of the corrie and on the floor, there appear to be several boulder moraines charting the advance and retreat of a glacier that last occupied the corrie. There has also been some discussion on whether a glacier also developed in the corrie during the 'Little Ice Age'.
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| Cairn Lochan and Coire an Lochain |
The benefit of good weather and with plenty of time until dusk, was the opportunity to explore the plateau, mindful of my footfall and trampling away from the path. That entailed keeping to more durable ground and avoiding the more obvious fragile environments and a note to self: establish exactly what my wanders had on the environment. The plateau is an upland area of the UK noted for its harsh climate and an assemblage of arctic/alpine flora. I soon discovered just how long winter endures on the plateau, as only the green leaves of Trailing Azeala and Alpine lady's mantle were apparent. My knowledge of montane grasses, sedges and rushes has scope for vast improvement and observations were limited to noting the transition from Nardus grassland around Feith Buidhe and the March Burn to Wooly Fringe moss blanketing the slopes down to the Lairig Ghru exposed to prevailing wind. The vegetation on the exposed Cairn Lochan dome and exposed slopes, is best described as fell field, with a mosaic of sparse vegetation communities dependent on the amount of shelter afforded by boulders and topographic depressions.
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| Rock mosses of the Andreaea genus, Rhizocarpon lichens, unidentified crustose lichen communities and Fir Clubmoss |
Of the lower plants, I did show willing and photographed some lichen and bryophyte communities, some of which I am happy to assign to a genus. Attempting to identify beyond the genus requires more knowledgeable and committed investigation: collecting specimens for microscopic examination, treating with chemicals etc
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| Rhizocarpon community and Rock Moss of the Andreaea genus |
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| Sphagnum moss ~ Feith Buidhe |
The plateau surface isn't level, but has a topography of broad domed summits, gentle slopes and open shallow valleys. The low topographic relief of the plateau appears to be relatively unmodified by glacial ice during the Late Glacial Maximum in contrast to glacial landforms that cut and dissect the plateau. The current paradigm is that the Cairngorm plateau is a palaeo land surface that stretches back into Deep Time.
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| View over Feith Buidhe to Cairn Gorm |
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| View over Feith Buidhe grassland to Beinn Mheadhoin and its granite tors |
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| View of the Cairngorm plateau over the March Burn to Ben Macdui |
Whilst exfoliation joints in granite are well displayed in the headwall of Coire an Lochain, it was interesting to view close up the exfoliation joints on bedrock outcrops and easy to see why they are also called pseudo bedding.
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| Foreground : Granite pavement. Middle distance : Block field transitioning to Block slope. Background : The glacial corries of Coire an Lochain Uaine and An Garbh Choire |
The plateau slopes down to the edge of the glacial trough of the Lairig Ghru providing an insight into periglacial landforms on slopes. Freeze thaw of ground water, ice and gravity causes mass movement of rock debris downslope and the slope gradient, aspect and character of the rock debris, all appear to contribute to the nature of the resulting landform be it stripe, lobe, terrace or sheet.
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| Boulder stripe and Wooly Fringe-moss heath ~ Cairngorm plateau |
There is compelling evidence for frost weathering (macrogelivation) of vertical cooling joints of the granite bedrock outcrops to generate autochthonous debris mantled slopes. Bedrock outcrops with dilated joints, had edges rounded from the effects of microgelivation, although elsewhere the rounded nature of boulders possibly indicates additional eolian erosion from wind abrasion. On some bedrock and loose rock surfaces there were large specimens of Rhizocarpon lichens and was reminded of research papers on Lichenometry that extrapolated ages for growth rates of lichens in high latitudes and reporting some significantly old ages for the lichens.
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| Frost weathering of granite cooling joints |
One patch of ground the size of a snooker table was bare of vegetation, fairly level and composed of decomposed granite surrounding a quartz vein, I can only speculate that the hydrothermal fluids associated with the vein quartz have lowered the competence of the adjacent granite to weathering processes. The unvegetated nature of the surface was most likely due to deflation by the wind, as a clump of Wooly Fringe moss was growing on a NE aspect of the quartz vein, in the lee side way from the prevailing wind.
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| Vein quartz su decomposed granite, Unbilicaia and Rhizocarpon Lichens. |
Some of the periglacial landforms are of a significant size and probably best appreciated from a distance, ideal subject matter for a telephoto lens to abstract the landscape and a small regret at jettisoning the telephoto lens from the rucksack for this trip. The Cairngorm plateau has plenty of opportunities for making landscape photographs with a narrative of landscape evolution in a montane environment.
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| View over a soliflucted boulder lobe to the Braeriach massif. |
I thought a rounded granite boulder emerging from the edge of a snow bed and covered with lichens, an abstract visual metaphor for the Cairngorm plateau.
The fell field on the slopes of Cairn Lochan provided a view of Braeriach.
On the way up I had thought there was potential for an image of last light falling onto the lower northern slopes and also illuminating the northern corries and descended, disturbing a few Mountain Hares on the way. Things didn't quite pan out for an image of the northern corries of the plateau, however a burn draining Coire an Lochain into Loch Morlich provided some inspiration.
The excursion up onto the plateau had been a good one, providing insight, things to ponder, views and a walk over some interesting terrain. I was surprised given the weather forecast that aside from a couple and their dog descending Cairn Lochan at about 17.00 hrs, I saw no one else until arriving back at the carpark around 23:00 hrs. Nic eventually arrived to collect me and her guided wildlife trip had been good too, with extended viewing of Pine Martens and Badgers from a hide in Rothiemurchus forest.
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