Trip report part 4 - The Cairngorm Plateau

The Mountain Weather Information Service delivered a very promising forecast for a hill walk, with the only concern being windchill in the worst scenario below zero, necessitating winter clothing to be packed. The Cairngorm plateau seemed an easy option with an elevated start point at the Cairn Gorm mountain carpark at 650m and mindful of the wind direction and sunset azimuth, it seemed wise to keep to the western edge of the plateau.

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.

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.

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.

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'.

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.

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

Rhizocarpon community and Rock Moss of the Andreaea genus

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.

View over Feith Buidhe to Cairn Gorm

It was evident from the depth and extent of snow lying, that the upper reaches of Feith Buidhe is an area where a significant quantity of snow accumulated over the winter and I later discovered that the area was where the events of the 1971 Cairngorms tragedy occurred.

View over Feith Buidhe grassland to Beinn Mheadhoin and its granite tors

The fresh easterly wind blowing up the Feith Buidhe valley, discouraged lingering and an impromptu visit to Beinn Mheadhoin's granite tors was discounted following careful scrutiny of the map. The sheltered slopes on the west side of the plateau held more appeal for continued exploration of the landscape.

View of the Cairngorm plateau over the March Burn to Ben Macdui

One of the impressive Quaternary glacial modifications of the plateau is the Lairig Ghru, a glacial breach of the plateau and a trough eroded by glacial ice. The light was all wrong for photographing the Lairig Ghru and haze in the Spey valley obscured the Monadhlaith, but nonetheless the photograph illustrates the breach and trough profile..

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.

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.

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.

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.

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.

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.

Braeriach and the blockfield on Miadan Creag an Leath-choin

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.

Another wild camp

Garreg Las is a minor summit on Y Mynydd Du, with extensive areas of glaciated pavement and periglacial landforms, a geology map shows an interesting outcrop pattern of geology and faulting, The OS map shows some topographic relief, open access upland and the time of year with the azimuth of sunrise to the north of the Carmarthen Fans. All in all sufficient inspiration for a wild camp trip to explore the dusk/dawn potential with a reasonable forecast and good visibility.

A window into the Y Mynnyd Du geology and faulting @ British Geological Survey

Parking up and it was good to see an absence of litter and information boards installed, even the limekilns and quarries were receiving some TLC, part of the Calch project on the areas long history of Lime production. The walk in was warm and I ended up pitching the tent near a small 'peat' pool on the NE flank of Foel Fraith, the level mossy turf almost negated the benefit of an inflatable mat. With the tent pitched, myself foddered and watered, I made my way over to Garreg Las, to record the geology and see what unfolded for sunset.

Foundered glaciated pavement

The sandstone outcropping on Garreg Las, is classed as a quartz arenite, a hard, durable sandstone and its competence is indicated by the outcrop exposure. Large areas show evidence of being scoured and quarried by glacial ice and there is evidence for periglacial processes breaking up the pavement and movement of loose material downslope into lobes and sheets. In places the quartz sandstone has foundered, presumably where the underlying limestone has dissolved away. Erratics resting on the foundered rock point to collapse after deglaciation.

Weathered surface

The sandstone pavement on the western side, appears extensively weathered, there is an absence of fresh striae and chatter marks and intriguingly there are some sizeable weathering pits/pot holes, landforms I have also seen on bedrock in the hills of the Cairngorms and Norway. It is thought that the formation of weathering pits is an erosion phenomena associated with high wind and the scouring or abrasive action by loose rock/grains and water. Field studies in the Cairngorms revealed limited formation of weathering pits/pot holes in recently glaciated areas and deeper weathering pits were confined to relict surfaces. Cosmogenic radiation dating of the Cairngorm bedrock surfaces with weathering pits revealed an exposure age range of ~ 21,000 - 79,000 years for glaciated areas and ~50,000 - 250,000 years exposure age for unglaciated areas. The vertical joint/fracture surfaces also displayed 'cavernous' weathering on the west side of Garreg Las, whereas I didn't notice any weathering on vertical surfaces on the eastern side, features that suggest two episodes of pavement break up. To my eyes, the weathered appearance and presence of weathering pits does suggest that some surfaces on Garreg Las have been exposed for a long period of time, on the other hand, it may just be a less competent area of sandstone.

Weathering pit 

The summit of Garreg Las, Twyn swnd, is adorned with a pair of large bronze age cairns, Carnau'r garreg las, and visible on the skyline from a number of directions, mostly from higher ground/upland areas.

Carnau'r garreg las

I'd hoped for a view to the north for sunset, but haze reduced visibility and on the NW horizon a solid band of cloud was evident with streamers of cirrus clouds. I was also beginning to question my wisdom at leaving a tele zoom out of the bag. Considering the options I headed back downslope to an area on Cefn y Garreg Las where there were some larger erratics and an area of flowering bog cotton.

Weak sunlight and Incoming cloud at sunset

Returning to the tent, I reflected on my inability to find a composition on Garreg Las that convincingly illustrated a down faulted block of younger geology against older geology. I made a note that the geological faulting of Garreg Las, would probably be better photographed later in the year towards the winter solstice using the low angle of light to model the geology and from a viewpoint elsewhere on Y Mynydd Du. Still, there was the promise of dawn and a view of the Welsh Borderland Fault System to north.

Sunrise

A look out the tent in the gloaming of dawn revealed the depressing sight of clear skies overhead and to the south, with a band of cloud to the north and north east. The 3rd successive photography trip at dawn with clear blue sky overhead and the sun rising into cloud, deep sigh. So, twilight photography bite the dust for a start, sunrise seemed destined to follow suit and when the sun eventually cleared the cloud, any shadows would be an unappetising blue shade, the colour cast courtesy of the overhead clear sky, not the best as grey rock would really accentuate the 'blue' shade. I had a dark suspicion that the band of cloud responsible for masking sunset, was the very same cloud mass which would now obscure sunrise. Still there was some mist around in the valleys and pretty good visibility, which gave some hope.

100mm field of view of Welsh Borderland Fault System

Reaching the northern slope of Garreg Las and a look out to the NE horizon gave confirmation that there would be no warm side lighting at sunrise.  Things looked more positive to the North with colour in the clouds and valley mist highlighting the Welsh Borderland fault system. I now wished I'd packed a telephoto zoom, as 100mm was too wide on the vertical angle of view and needed a vertical crop to get the view sans foreground. The Welsh Borderland fault system delineates a terrane boundary separating the Cymru and Wrekin terranes, stretching from Pembrokeshire to Shropshire.

Desired crop

On up into the boulder field and with neutral coloured rock, I really would have liked the warm light of sunrise and cloud overhead. Instead it was matter of trying to find a view that showed the extent of the periglacial breakup and mass movement of debris downslope and keep enough warm light rock to offset the blue shade.

A powder blue sky and harsh summer light, meant my inspiration dried up shortly afterwards and it was a case of recording some geology outcrops on the way back to the tent and the journey back home reflecting on events.

Why?

The southern slopes of the Black Mountains were visited, again.  Which raises the question - why?  The answer is complex.  This area of the Black Mountains has a suite of landforms which appear to relate to phenomena associated with a very cold climate.  Debris from rock slope failures - possibly paraglacial or seismic in origin - appears extensively modified by periglacial processes. More surprisingly, Table Mountain is also thought to be a landslide, resulting from the down wasting of a valley glacier. Both events are thought to have occurred towards end of the Devensian stadial, but there are also alternative theories, it's an interesting wander and the landform suites possibly relate to a number of climatic events.

There are also the insights along the route, from the impact of farming - Ffridd wall, hedge laying, woodland management and relating the the underlying geology with flora. There is also the intangible pleasure of observing the rich tapestry of nature, viz on this trip; a Red Kite shadowed by two Ravens; a Wren foraging in the block slopes; a Fox crossing a distant field; a field conspicuously littered with Mole hills; Fairy inkcaps in a decaying Oak, berry laden Hawthorns, hill ponies grazing, scat on a prominent boulder - the lichen community reflecting a nutrient rich environment and hinting strongly that this boulder has demarcated an animals territory for a while ...

There's also the benefit of stretching the legs and schlepping the photography kit helps puts some debit in the calorific bank, with the festive season calorific binge looming...

Fairy Inkcaps ~ Leica apo macro elmarit 100/2.8

Leica vario elmar R 21-35mm Asph

Then there's the creative itch to be scratched, making a photograph, especially with the quality of light around the winter solstice, when the sun is at its lowest zenith, with a backdrop of broken cloud, rain showers, sunset and with good fortune, there's real potential for atmosphere. The good fortune is light shining through a break in the cloud illuminating the scene. My fortune on this trip was mixed, well broken cloud on the ascent, the first image captures the last light before a hill spur shadow falls across the boulder lobe. The second image has warm but weak sunlight filtered through cloud, the main sunbeam was slightly higher up the hillside, the cloud was failing to breakup sufficiently over the Brecon Beacon massif to the WSW.

Leica vario elmarit R 28-90 Asph

I thought that was the light gone for this trip, the cloud seemed unbroken to the south west, obscuring the sunset and so made my way back across the block slope, as I wanted to look at possibilities for a dawn scenario. On the way some 'Dog Lichens' (Peltigera membranacea) caught my eye.

Dog Lichens ~ Leica vario elmarit R 28-90 Asph

Sunset was a non event, but the cloud was breaking up to the south and dusk provided a display of red/magenta lighting reflected from and diffused by the clouds, a welcome and unexpected bonus. The wind eased too, which was helpful as exposure times were in the order of 4 to 8 seconds duration in the gloaming light.

 Leica vario elmarit R 28-90 Asph 

 Leica vario elmarit R 28-90 Asph 

The opportunity doesn't arise that often, but it is interesting to make images in the colours of dusk, the human eye doesn't pick up the colours as well as the camera sensor and for this trip it was definitely worth waiting around for.

Showing willing

Two successive trips, both to the same location and both with a forecast of broken cloud and sunshine.

1st trip
The clouds indeed were breaking up, there just wasn't enough cloud and the sky was probably 95% cloud free, which offers the prospect of distinctly uninspiring cool blue shadows and cyan sky.

The cloud breaking up

It's fair to say my inspiration level dimmed a bit and I abandoned the big view for what was on offer on the ground, amongst the boulder lobes.

Lichen community

2nd trip
Was a sky of unbroken cloud, but with blue skies to the West, there was a tantalising prospect of the cloud breaking up or clearing,  towards sunset.  The diffuse light was more suited to studies of the ecology of the upland environ and the Ffridd wall provided some inspiration.

Ophioparma ventosa

Parmelia saxatilis with lichenous fungi

Moss and lichen community

Moving on up onto the open hillside, above the bracken line and into grassland, heavily grazed by hill ponies and sheep, but crucially never improved with fertiliser or ploughed, the ancient nutrient poor soils are a haven for fungi. Surveys of Welsh uplands reveal its international importance for many species of grassland fungi and it's known by ecologists as 'Waxcap grassland'.

Scarlet Waxcaps

Orange Waxcaps

A wander around some impressive landslide debris and then it was time to commence the vigil for sunset and a view across the hillside, over landslide debris (paraglacial), soliflucted boulder lobes and till (periglacial) to the southern outliers of the Black Mountains. By the time the cloud cleared, the sun had already set ... IF the cloud had cleared 20 mins earlier, the foreground would have been awash with the last light of sunset, the retreating cloud sheet would have turned magenta ... on such small margins, sigh.

Blue Hour

The cloud at least presented an opportunity for a 'blue hour' image and then it was on with the head torch and a journey down to the car. A landscape photographer certainly needs a philosophical outlook on weather and observing/photographing the ecology helps to make a trip worthwhile when the weather doesn't play ball.

An Orange Blorenge

A later than planned start and driving down the A40 it was noted that the weather/air clarity was less than inspiring. So, Plan A - calf muscle testing ascent up Mynydd Troed was switched to Plan B - a leisurely wander around the Blorenge instead, the Foxhunter carpark is handily placed for minimal exertion.

It had been 6+ years since the last visit and things had changed out on the moorland. At some point in the intervening years an extensive (managed?) hill fire had burnt away the leggy heather and young heather plants were rejuvenating the moor.  The heavily eroded main path from carpark to summit had been resurfaced and there seemed to be a complete absence of litter, hopefully a positive sign that people are respecting the environment.  Two pairs and a trio, equalled a total of 7 Red Grouse sighted, apparently the Blorenge is the furthest location south in the UK for Red Grouse and another positive, always good to see the native wildlife.

The periglacial block fields on the northern slopes also have the potential for a composition with the Black Mountains as a back drop and fortuitously the sheet cloud started to break up in time for sunset.

I can think of numerous times when far more onerous trips have met with scant reward, but autumnal low angled sunlight, under low cloud is not bad at all.