A circuit in the Black Mountains

After a grim period of weather the Met Office served up a compelling weather forecast for a wander onto the hills.

Taking into account the wind direction, likelihood of showers and sunset light, the Black Mountains were chosen and a circuit of Cwm Banw. Nic was enthused enough to accompany me. Ascending through the fields a local farmer was met and a brief chat about the impact of Storm Emma elicited that about 2 feet of snow had fallen and drifted to very impressive depths, all the minor roads were blocked for a few days and it had taken the farmer 15 hours to dig a route to get feed to livestock, a journey that would normally take 5 minutes. To illustrate the severity of the weather event, 2 weeks on there were still snow patches a few feet deep in the sunken holloway on the path up. Reaching the open moorland and sadly the weather changed from blue skies, fluffy white clouds and warm sunshine to more ominous looking clouds, much less blue sky and the donning of winter jackets.

Landforms and patterned vegetation in the Black Mountains

The Black Mountain environs exhibit a curious mixture of landforms from plateau surfaces that suggest relict planation surfaces 10's of millions years old to those attributable with more confidence to repeated glaciations in the pleistocene. Areas of patterned vegetation may be associated with underlying superficial deposits that have been subjected to periglacial processes. Illuminated by more desirable light these would have been more apparent and a mental note was made to revisit at a more optimal time of day and year.

Squall lighting and open moorland

The best lighting occurred on the approach to Pen Allt-mawr where foreground composition was limited to moorland vegetation and a simple demonstration on the why side lighting is preferable for saturated colour.

The approach to Pen Allt-mawr

On reaching the summit of Pen Allt-mawr the squall hit with rain quickly turning to sleet and the novelty of ice coating any exposed clothing. Nic was less than impressed. Still there were grand views to the west until the hill fog obscured everything. I raised the prospect of waiting for the squall to pass and received the look of mutiny from Nic. The planned high level exposed plateau circuit of Cwn Banw walking into wind driven sleet held little appeal and instead we made our way back to the car via a lower, less exposed route. A consultation of the OS map indicated a stream would need to be crossed and that stream would no doubt be swollen. So the return route would keep to a high level and basically contouring, which explains why several relict vegetated periglacial boulder lobes were traversed and on another day these would have presented some photographic foreground interest rather than tiresome obstacles. I feel confident in stating that this particular area is not well visited. Eventually the squall passed, hill fog cleared to make navigation easier and then a brief break in the clouds allowed some sunshine through illuminating the coed cae on the south facing slopes of Cwm Banw and the Sugar Loaf hill in the distance.

A view down Cwm Banw to the Sugar Loaf. 

The stream was easily crossed at a higher elevation whilst lower down the white water suggested very high water flows and probably a more challenging crossing. We made it back to the car just before another squall arrived, a good end to the trip and some locations to be revisited.

An east wind is no good for man nor beast.

The weather forecast for the Brecon Beacons National Park was:

Screen shot from Met Office https://www.metoffice.gov.uk/public/weather/mountain-forecasts/brecon-beacons

The windchill of -10C at 600m something to consider.

Screen shot from https://www.metoffice.gov.uk/public/weather/mountain-forecasts/brecon-beacons

Nic was suitably enthused by the forecast that she decided to accompany me with the enticing prospect of a good walk with late light illuminating the bleached moorland vegetation, rock outcrops and a possibility of twilight alpenglow. A check on other forecasts indicated the wind might well be stronger than the met office forecast and before leaving a check on the visible satellite imagery indicated there was cloud moving across the park from the east. The trip destination would be decided en route determined by the prevailing weather with the Black Mountains, Brecon Beacons and Fforest Fawr all in play. At Abergavenny the Black Mountains were ruled out by cloud and haze. From the highpoint of the A465 the visibility was excellent and the wind very 'fresh', ruling out the Brecon Beacons. Fforest Fawr would be the end destination. The walk was delayed waiting for a helpful farmer to pull the car from less firm ground, sigh, wheel mats under the tyre had proved useless.  However if you were going to get stuck, then this was a good place and time, sheltered from the wind, views, warm sunshine to bask in and a road only used by the farming community who were pro-actively preparing for a sustained cold blast of air from Siberia. After heartfelt thanks and lightening my wallet to reward the good samaritan farmer, I managed to park the car on more firmer ground, not my finest hour and Nic was less than impressed.

Exposed moorland, Devonian sandstone glacial erratic, limestone pavement, sink holes and haze.

Finally underway and on reaching the exposed moorland the wind was a tad stronger than expected, the windchill very noticeable, haze obscured views of the Brecon Fans and haze/cloud bank on the western horizon scuppered any hope of sunset light or alpenglow. A small positive was that the peat bogs were frozen.  A place of relative shelter was sought near a viewpoint and a cunning plan concocted. The plan involved minimising exposed walking and maximising taking in the views from sheltered sites, whilst basking in the warmth of sunshine.

Google satellite view illustrating the density of sink holes.

The area has one of the highest density of sink holes (dolines) in Britain and the geology of limestone, limestone overlain by quartz arenite sandstone and areas mantled by glacial till and peat, means there are good expressions of many sink hole types.

Sink hole (doline) types. Illustration from http://www.bgs.ac.uk/caves/sinkholes/home.html

To successfully photograph the extent of the sink holes requires very low angled side lighting and not for the first time the desired lighting failed to materialise at this location. Nevertheless there were views and limestone pavement to offer some foreground interest and relief from late winter moorland vegetation.

A good walk, decidedly fresh air, geology interest and some moorland visited which would otherwise have been overlooked in better weather.

Isle of Skye - Geology

The Isle of Skye has a long geological history, illustrated by a Geology Excursion Guide that has 21 detailed itineraries, the majority are of 8 - 10 hours in duration. Located on the Atlantic coast of Scotland there is the prospect of some changeable weather, which means there is the opportunity for making a landscape photograph with a narrative of the geology and/or geomorphology.

View from the western slopes of Marsco  ~ 2013

One particular geological feature has played on my mind, since my last visit to Skye, in late November 2013.  I had followed an excursion in a geology guide book, down Glen Sligachan and ended up in Harker's Gully on Marsco, that has exposures of intrusive rocks in a composite ring dyke. In lieu of typing verbatim the geology guide description, there is a description of the ring dyke and its context within the western Red Hills (volcanic) centre on the BGS Earthwise blog or Geological Conservation Review. The ring fracture was differentially weathered into a gully and a distinctly verdant flora compared to that growing over the thinner soils on the adjacent granite bedrock. That geology excursion was compromised by the distraction of the views over Glen Sligachan to the Black Cuillins, glacial geomorphology and the course of the River Sligachan, that in places delineates the boundary of the gabbro and granite intrusions.

Screen shot taken from http://mapapps.bgs.ac.uk/geologyofbritain/home.html to illustrate Marsco hybrids of the western Red Hills Centre

For those curious about Britain's bedrock, the British Geological Survey has an excellent Geology viewer application to investigate the landscape. Below is a satellite image taken in late winter of Marsco, judging by the snow lying on the Black Cuillin, shadows and the drab brown foliage. Clearly visible are stripes and patches of green foliage.

Screen shot taken from http://mapapps.bgs.ac.uk/geologyofbritain/home.html to illustrate Marsco hybrids of the western Red Hills Centre

 Clicking on a green strip reveals the underlying geology as mapped by field geologists, which is the Marsco Hybrids.

Changing the geology transparency layer reveals the underlying geology and the green foliage correlates with the outcrop of the Marsco Hybrids.

On the visit to Skye in late October 2016 and in the itinerary under 'iffy weather' there were a list of geology excursions and two in particular explored the nature of the ring dyke further. First up was an impromptu geology excursion to the John Muir Trusts, Sconser estate, that proved interesting, but probably best visited after some drier weather, with lower water flows to make crossings easier and when the Sligachan 'peatlands' are less saturated. The plateau basalts, Glaimaig granite and the composite ring dyke of Marsco Hybrids are revealed in the stream exposures of bedrock and also on the north spur of Druim na Ruiage the Marsco Hybrids are revealed by verdant green flora against the autumnal russet flora of the sedges and grasses. Sadly by the time I had got to grips with the geology exposures, the weather had really deteriorated and dusk arrived. Nevertheless, I was impressed with the potential of the area and the backdrop of the Red Cuillins.

After arriving on Skye, Nic booked a kayaking trip on the day before we departed Skye and at the time the plan was to drop me off somewhere and then pick me up somewhere else at at dusk. The weather forecast deteriorated, with a weather front spreading in from the north around midday and so the plan changed, to me dropping off Nic and picking her up from the kayaking offices, giving me a window between 09.00 - 16.00 hrs. The leading edge of a weather front can deliver some atmospheric weather, so I decided on a walk up into Coire nam Bruardaran,  which was also covered by a geology excursion I could cherry pick from and if the opportunity arose, wander up a hill summit if the weather held. After dropping Nic off in Lower Breaknish, I parked up at Loch Ainort and the weather was pretty good, a few wisps of hill fog over Glaimaig, but the higher summit of Gharb-bheinn clear. A beeline was made for Gharbh-bheinn, the geology could wait until the descent. An hour later and the summit of Gharb-bheinn was 'clagging' up, sigh. I was passed by two local hillwalkers, who in view of the dire weather forecast, were heading up Gharbh-bheinn for a shorter hill day in preference to the Black Cuillin. In view of the hill fog I decided to concentrate on the geology and views from Druin Eadar Da Choire and Point 489.

Topographic expressions of weathering and erosion.

Where the ring dyke crosses the ridge of Druin Eadar Da Choire, its presence is revealed by a gully, the ground vegetation is less convincing, although the signature of the verdant flora corresponding with the Marsco Hybrids is readily apparent on the eastern flank. The view across Coire na Seilg, juxtaposes the weathering and erosion profiles of differing lithologies : granite of Glas-Bheinn Mhor and assorted intrusive/extrusive basic rocks of Belig.

Onwards to point 489, which for a modest elevation has extensive views. Any lingering hopes I had of taking in more elevated views were dispelled by incoming cloud and orographic fog. I should add that the western summits of the Black Cuillin appeared to be largely free of cloud/fog, whilst the lower tops of the Red Hills were afflicted by cloud/fog. A 'wee blether' with the two hillwalkers on their return journey, revealed that they did get a brief view from Gharb-bheinn's summit.

I did chance upon a Hard fern nestled in an outcrop of granite accompanied by some Fir clubmoss.

The western slopes of point 489 had extensive granite block fields against a backdrop of Marsco and the Black Cuillin. I did keep an eye out for any glacial erratics, but didn't notice anything, which suggests the block fields are autochthonous and generated under periglacial conditions, some areas of the slopes had distinct banded pattern of vegetation and block stripes, landforms indicative of periglacial mass movement.


The dark basic rocks of Garbh-bheinn, provided a contrasting backdrop to the granite block slope. The name given to this area is the Red Hills, I somehow arrived in an area where the geology comprised either dark basic rock or granites that were blue/green/gray when fresh and gray/brown when weathered. The weather as forecast deteriorated and I made my way back to the car, not a bad excursion and an area to return to again one day. I'll cover other excursions on the Isle of Skye in the next post.

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.

Scowles

Recent trips have been local and partly spent investigating the potential of some scowles sites for sunrise and sunset light, though assessing where low angled light falls and what it illuminates within a woodland is an exercise in optimism. The scowles land features are possibly unique to the Forest of Dean and Lower Wye Valley and generally associated with the outcrop of carboniferous crease limestone. The geology is haematite mineralisation in fractures and solution cavities, the surface expression is anthropogenic, from the open cast mining of haematite. Normally the prospect of photographing mineral workings isn't one to set my pulse racing, the scowles are the exception. The simple reason is that the mineral working activity happened a long time ago, archaeologists aren't sure exactly when, though there is historical evidence that points to Roman age workings. Some believe the scowles are older than Roman.

Scowles woodland

Most of the remaining interesting scowles landscape have been naturally regenerated by woodland and this woodlands by most definition satisfies the criteria for ancient woodland - Beech, Ash, Hazel, Yew, Holly, Oak, Lime, Wych Elm, Gean, Wild service and Whitebeams. Outsize ancient coppice stools are not uncommon and Yews have a character that suggests trees of some age.  The ground flora over limestone and dolomite is calcicole and again indicative of ancient woodland. The high rainfall in recent years appears to have encouraged Ramsons and a carpet of Ransoms is worth making an effort to photograph, especially when it picks out the undulations of mineral workings.

Scowles woodland 

The picturesque aesthetic of scowles were appreciated by early 19th century tourists and this trend has continued to the present day, the latest Star Wars movie utilised the Puzzlewood scowles as a filming location for that otherworldly je ne ce quois. Away from the relatively manicured environs of Puzzlewood, scowles environments are more visually complex. The vibrant greens of foliage, extremes of contrast and colour gamut and colour, make for some interesting exposure decisions.

Scowles ~ Yew roots and geology

Recent trips haven't really produced any images of notes, documentary records of the scowles mostly, the rewards might come later in spring if the wind drops.

NW Highlands trip report - part 3

I have a simple philosophy on hill walking and the number one rule is - I ain't going up in crap weather. The primary appeal of visiting a summit are the elevated views of scenery, the novelty of walking in a cloud and/or on all fours to prevent being blown over, has long worn off. Happily I haven't succumbed to ticking off hill lists nor do I suffer from summit fever, so I'm prepared to bide my time until the weather cooperates. The long awaited weather forecast for a hill excursion arrived and despite the attractions of Beinn Allign, Beinn Eighe was chosen as it would offer outstanding views not just of the scenery, but also of the geology. The summits were forecast to clear of cloud by the afternoon, so it was a relaxing start at 13.00 hrs from Glen Torridon, with an eye on sunset photography from the ridge.

The peak of Spidean Coire nan Clach and view north over the Moine Thrust Belt to the Letterewe Forest

The walk up is initially on a well constructed stalking path with plenty of zig zags to ease the ascent gradient and then briefly levels off before ascending into Coire an Laoigh. Where I was delighted to chance upon an emerald waterfall of mosses.

Egress from Coire an Laoigh to the ridge is either via the horror of scree, angled rock slabs or the munro baggers trench and bypass paths that scar the grassy slope of the corrie head wall. If I returned to the ridge again, I would probably take an alternative approach from Slugach via Coire nan Clach.

Stuc Coire an Laiogh and the Coulin Forest

Whilst taking in the views from the col between Stuc Coire an Laoigh and the ridge, a Golden Eagle quartered the slopes below us, the first time either of us had seen an eagle from above. Up onto the ridge the views were indeed excellent and visibility was improving.

Beinn Eighe - Western summits

Beinn Eighe - Eastern summits 

A wander over to Spidean Coire nan Clach and Nic's debut Munro. Whilst taking in the views a fell runner appeared and a wee blether ensued, he'd made the ascent in 39 mins! whilst the descent might take 19 mins! A physique of sinew and muscle, with a job as a head stalker on Gairloch Estate, fell running since a boy, a born and bred hill man. He also enlightened us on the deer mortality rate over the winter and provided an insight into the hills and winter conditions. Interesting that Liathach, the massif adjacent to Beinn Eighe, was the one mainland hill he really didn't like, even more so, since a fell running friend had died on it a fortnight before. Watching his descent down the ridge can only be described as a fluid motion over rugged terrain.

Coire Ruadh-staca and a suit of glacial landforms on the corrie floor 

The view north into Coire Ruadh-staca reveals a suite of hummocky and lateral landforms, moraines indicating the downwasting and retreat of the corrie glacier at the end of the Loch Lomond stadial. By turning around 180 degrees and looking south across Glen Torridon into Coire a' Cheud-chnoic (Valley of a hundred hills) a suite of hummocky moraines gives the valley its Gaelic name.

Glen Torridon and the hummocky moraines of Coire a' Cheud-chnoic

What can also be appreciated from this vantage point are oblique views over the Moine Thrust Belt and an insight into the architecture from an elevated viewpoint. A link to a video to modelling the formation of thrusts :



With an elevated oblique view across the Moine Thrust Belt, the pale quartzites and bands of dark or vegetated Torridon sandstone hint at the nature of the thrust belt, which in the image below is the northern part of the Achnashellach culmination, an imbricated thrust stack.

A view over Glen Torridon to the Achnashellach culmination of the Moine Thurst Belt

It is fair to say we loitered on the ridge for a while taking in the views, the haze seemed to drift in and out, which provided a memorable view of Liathach bathed in crepuscular rays

I had hoped to stay up on the ridge for sunset but a large bank of cloud out west didn't hold much promise and Nic didn't fancy the descent in head torch light, so the last images were made before the descent back down into Coire an Laoigh.

We arrived back at the  car in the gloaming and I was relieved that I hadn't noticed any late light falling on Beinn Eighe since our departure. A good day.