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.

Upland birchwoods

A recent trip to the Scottish Highlands, staying at Kinloch Rannoch and upon arrival it was apparent the autumnal colour palette of deciduous trees, meant plans needed to be revised, to take advantage of the photographic opportunity presented. The appeal of photographing upland birchwoods, increased after a frustrating trip up Ben Lawers, that achieved nothing more than the following a 'munro baggers trench' and some very infrequent breaks in a persistent band of cloud that blanketed the summits and obscured the views. Disappointing, as I venture into the hills for the views, not to tick off a hill list. The small consolation of the Ben Lawers ascent, was a brief, but impressive Brocken spectre.

I decided that my photographic ambitions be revised from summit views, to finding an autumnal upland birchwood, with hills in the background under an atmospheric sky and given the iffy Mountain Weather Forecasts, of high winds and low percentages of clear summits, it seemed a wiser choice.

Ordnance Survey maps were appraised for deciduous woodland, then cross referenced with online historic 1:10,560 OS maps and then satellite imagery, to eliminate newly planted or regenrated woodland. A comparison of modern OS maps and the 19thC OS maps, also lends credence to woodland historians assertions that some upland birchwoods are mobile in the Highland landscape. It soon became apparent that there were a number of locations to choose from and in absence of a strict definition, I decided that anything above the 300m contour line would be a reasonable basis to define an upland birchwood, ecologists would rightly beg to differ, but it seemed a reasonable cut off point for my needs. Locations were then assessed for : geology interest, interference of views from municipal infrastructure, expansive views etc and a list of potential sites arrived at to visit, weather permitting.

The weather duly obliged with sunshine and showers.

Of the upland birchwoods visited, some had been enclosed with deer fences to allow natural regeneration to take place, whilst others were left open and I can only assume that deer were being controlled, as there were signs of woodland regeneration with saplings growing. Where there were no deer fences or apparent controls on grazing pressure, the woodland showed no signs of regeneration. In all the upland birchwoods visited, Bracken was conspicuous by its presence in the field layer and adjacent landscape, prompting some ecologists to speculate that these were formerly Oak woods.

A ravine chanced upon, revealed the potential for the wider Highlands landscape, if the grazing regime changed. The mixed woodland consisted of: Aspen, Rowan, Hazel, Willow and Birch, that contributed to an excellent autumnal colour palette

The decision to lower ambitions from summits to lower elevations proved a good decision and some less visited parts of Perthshire were explored.

The 5th Kingdom - Intro

Read anything about Fungi and some surprising facts are revealed. Not until 1969 were they classified as being a separate kingdom distinct from plants and animals. Another thought provoking statistic, is that in a broad leaved wood, 10% of the biomass is fungi, which is a considerable mass and not one that is readily apparent. Fungi only become readily apparent when they produce their fruiting bodies to disperse spores and Autumn is the prime time for that event in my local woodlands.

Blusher (Amanita rubescens)

The various Agarics, Amanitas, Bolettes, Brittle Gills, Ink Caps and a host of other fungi emerge from the leaf litter and dead wood.

Upright Coral (Ramaria stricta)

The Forest of Dean provides a range of habitats, from veteran trees to old grasslands, for an impressively diverse number of fungi species. Mycologists of the Dean Fungus Group run Fungal Forays all year round and the number of species recorded so far by the group, runs into the thousands and are listed on a 104 page pdf.

Newly emergent Grey Spotted Amanita (Amanita excelsa)

This year I resolved to make a concentrated effort to learn more about Fungi and make a photographic record of my endeavours. I'll post more in due course.