Looking from the Creag Dhubh crags towards the snow-covered plateau of the Cairngorms

Last weekend I attended a two-day Introduction to Scrambling course at Glenmore Lodge. I had undertaken this course before, in August last year but was only able to attend for the first day. On that previous course the instruction group spent the day in the Chalamain Gap in the northern corries area of the Cairngorms setting up anchor and belay points in the steep bouldery ground and setting up indirect belays using the rope alone, much as for ML training.

On the first day of this course the group was based on the crags of Creag Dhubh near Newtonmore. The Cairngorms had an unusually extensive cover of snow for mid-May, down to an elevation of about 500m, meaning that many good scrambling routes and sites were under snow so they were not suitable for this introductory summer course, forcing the course instructor to go a bit further afield. The crags on Creag Dubh are also at a relatively low elevation (about 400m), whilst still presenting many challenging sections of scrambling as well as many full rock climbing routes. The weather on this day was perfect, with blue skies and little wind, with fantastic views of the snow-capped Cairngorm summits to the east and Creag Meagaidh and Ben Alder to the west.

On the Creag Dhubh crags above the river Spey

On Creag Dhubh our group traversed tricky boulderfields and steep grassy sections as well as setting up some simple anchor and belay points using a rope. We also practiced waist belays, direct belays and the use of a sling and karabiner with clove and italian hitches to set up anchors for climbing, lowering and abseiling, all things that were new to me and which were not covered on the previous course last year and which go beyond the ML syllabus (but which are very useful for groups on scrambling routes). After the day at Creag Dhubh the group spent and hour in the indoor climbing wall at Glenmore Lodge practicing basic climbing techniques, which was something I hadn’t done since the age of about 20.

On the second day the weather had considerably worsened, with storm force winds and heavy rain forecast. However the temperatures had risen considerably causing a lot of the snow in the Cairngorms at lower elevations to melt overnight meaning the group was able to spend the morning on a steep area of granite crags and boulders on the east side of Coire na Ciste in the northern corries. This was the same crag that I had spent a day on on an ML refresher course in May 2010 (see the previous blog posting ‘ML refresher course‘), although on this course the group undertook considerably more difficult lines of scrambling ascent, some unroped, and some protected with anchor and belay points set up with sling and karabiner. Some of the moves required to negotiate the steep boulder steps were quite tricky in the strong gusty wind and I was right at the limit of what I could achieve. A lot of this morning was spent on scrambling that was not really any different to rock climbing, and was probably amongst the most difficult things I’ve ever done, mentally and physically, since I was in my early twenties.

Due to the weather conditions, the afternoon of the second day was spent by the group in the indoor climbing wall at Glenmore Lodge but I chose to spend the remainder of the day outside, going for a short hike in Glenmore Forest which provided some shelter from the wind, walking along two large glacial meltwater channels which were carved out at the foot of the minor summit of Airgiod-meall at the end of the last ice age.

One of the engines from the B-26 Invader lying partially submerged in boggy ground

Last week I travelled to Ayrshire and went for a hike in the remote and anonymous moorland of East Ayrshire. The weather last week was extremely good, with blue skies, high temperatures and little wind, and this walk felt more like it was happening in the middle of summer than mid-March.

I walked northwards from the B743 into the featureless and boggy terrain of the area. There are two aircraft wreck sites in this area, and I had made a previous attempt to walk to these locations earlier in the year, setting off from the A71 to the north but was thwarted by difficult terrain and a new windfarm being built in the area which caused me to take a diversion.

The two aircraft, a Royal Navy Grumman F4F Wildcat/Martlet and a USAF/Armée de l’Air (French Air Force) Douglas B-26 Invader crashed in 1944 and 1956 respectively.

The wreck site of the Martlet consists of a single small pile of largely unrecognisable small sections of metal debris, about 500m east of the summit of Auchenlongford Hill on Blackside at an altitude of about 400m.

The crash site of the Douglas B-26 Invader lies about 2.5km to the north of this site, at the head of the Avon Water river, in an area labelled as ‘Draw Grain’ on the OS 1:25,000 map of the area, between the minor summits of Distinkhorn and Wedder Hill on Blackside. It lies in a shallow gully at an altitude of about 340m and the large debris field is about 240m in length. Despite being at a relatively low altitude, the site is fairly inaccessible as all approaches are on pathless, featureless, boggy and difficult terrain.

Many substantial parts of the Invader are still recognisable including one of the engines half-submerged in boggy ground, sections of what appear to be armour plating, a fuel tank and an undercarriage section. A small crater contains many burnt and mangled pieces of wreckage and it is possible that the other engine was largely destroyed.

Another interesting piece of wreckage at this site is a large tyre. Another unusual aspect of the site is a box containing a visitor’s book, a unique feature of this particular wreck site.

You can see my page about these wreck sites on my website here.

JMT volunteer work party carrying out path repair work (new boulder steps on the new path) on Schiehallion

On Sunday last weekend I travelled to Schiehallion to join a party of John Muir Trust volunteers undertaking path repair work on the maintained path that is situated on the long eastern ridge of the mountain.

The John Muir Trust (JMT) is an environmental conservation charity and landowner and owns several parcels of land throughout Scotland, including many in mountainous and remote areas (Bla Bheinn on Skye, Ladhar Bheinn in Knoydart and Ben Nevis in Lochaber) and organises conservation work parties throughout the year composed of volunteers to carry out work on the land such as path and fence maintenance, litter clearing and woodland regeneration.

The Trust takes its name from John Muir, the pioneering Scottish conservationist who was largely responsible for the creation of the idea of National Parks such as Yosemite in the Sierra Nevada mountains of California to protect areas of wilderness in the USA from commercial and industrial exploitation. I recently joined the Trust and also visited the birthplace museum of John Muir in Dunbar in East Lothian, not far from Edinburgh. I have also just finished reading The Wilderness Journeys, a collection of his writing.

JMT volunteer work party carrying out path repair work (spot turfing of old path) on Schiehallion

This is the first time I have done something like this, so I was unsure what to expect but ended up having a very good day. The day started at 9am in the Braes of Foss car park, the usual starting point for the walk to the summit of Schiehallion, and finished about 6pm. Since buying the East Schiehallion estate in 1999, the Trust has carried out a huge program of work on the mountain, removing the badly eroded original path up the mountain and creating a new one which travels up to an altitude of nearly 900m on the east ridge, and the party I was in carried out work on the path right up to this point, so I had to be equipped for a full day of mountain hillwaking. The kind of work I got involved in was creating boulder steps on steeper areas of the new path, cleaning drainage culverts and spot turfing on the surface of the old path to help the vegetation recover. I think a good description of all of this would be mountain ‘gardening’, as it was lots of muddy work digging trenches with mattocks and spades and shifting large boulders of quartzite with pinch bars, but high up on a Scottish mountain instead of in a garden in a town or city.

I first climbed Schiehallion in April 1995 before the new path was constructed and I remember the badly eroded and wide muddy old path how it used to be. The new path is an enormous improvement and has been constructed in such a way that it only uses materials taken from the surrounding area and ‘funnels’ walkers into a narrow area so it minimises as far as possible any impact of human intrusion into the natural environment.

To add to the ‘environmental’ theme of the day (and perhaps more importantly, to share petrol costs!) I gave a lift in my car to a couple from Edinburgh, Anna and Paul, who had not climbed Schiehallion before but took the opportunity near the end of the day to walk up to the summit.

The work party was very lucky with the conditions during the day, with blue skies all day (apart from a couple of small light snow showers). The air was exceptionally clear, giving amazing views towards Loch Tummel, Beinn a’Ghlo and a few of the summits in the Cairngorms, which did distract a bit from carrying out the sweaty physical labour! For mid-March, conditions were also benign in terms of the unusual lack of snow on the mountain which meant useful work could be carried out at a fairly high altitude, which must be relatively rare for this location at this early spring date. The lack of snow was also notable on the surrounding summits, giving the mountain landscape an appearance more similar to that of June than March.

From the path a good view was also had of a line of electricity pylons to the east which form part of the Beauly to Denny power line as it routes through the Pass of Keltney. It appeared that some surveying work was being carried out on the line, presumably connected with its redevelopment and upgrade. The newly-constructed Griffin wind farm was also visible from the path on the south-eastern horizon.

Cross-country skiing is something I have always wanted to try and my interest was rekindled recently after reading Adam Watson’s accounts of cross-country skiing journeys in his recently-published autobiography (see my recent blog post ‘It’s a fine day for the hill‘). It is quite different from regular alpine or downhill skiing, using different techniques, boots, bindings and skis.

The two day course was quite intensive and physically tiring but by the end of it I could use the skis and poles to move forward in the correct way, and move uphill and downhill and make some attempts to slow down and turn on slopes.

Unfortunately, although this was a February course, there was no snow available at the nearby cross-country skiing routes in Clashindarroch Forest to try, but the outdoor centre in Huntly has some good artificial surface areas for practicing on.

The next step for me will be to wait for some fresh snowfall and practice on real cross-country skiing trails with some hired skis, possibly at the Aviemore and Glenmore Snowports School near Aviemore. My ambition is to one day use cross-country skis for covering distance on winter routes in the Cairngorms, maybe even high up on the plateaux.

The granite tor on the summit of Clachnaben

Last week I travelled to Aberdeenshire and walked to the 589m summit of Clachnaben from Glen Dye. Despite being a relatively small hill, Clachnaben is very distinctive in having an unusual and large granite tor on the summit.

The weather conditions on this walk were quite unusual with not a trace of snow for many miles around despite the late winter date (February 24th). Temperatures were quite mild and the air was very clear but the wind was very strong so it was cold higher up the hill.

Views from the summit were excellent, with views to Mount Battock, Bennachie and the only snowfields visible on the Cairngorm summits. The North Sea and the tower blocks of Aberdeen were also visible to the east, as was the Firth of Tay and the outskirts of Dundee to the south. The summit tor provides some easy scrambling to get to the top, but this wasn’t very pleasant in the high winds.

Clachnaben is also notable in having two aircraft wreck sites near its summit. These two aircraft both crashed about 1.5km south-west of the summit and the two wreck sites are only about 1km apart.

One of these sites is that of a Hawker Audax which crashed here in 1939. The Hawker Audax was a variant of the Hawker Hart biplane. This Audax wreckage site is one of the oldest remaining in Scotland, and is the only pre-Second World War site I have visited. The wreckage has lain at the site for over 72 years.

At the site, which lies at an altitude of about 500m just south of the minor summit of Hill of Edendocher, lie the remains of the main fuselage and wing airframe along with a few other smaller pieces.

Kestrel engine from the Miles Master, summit tor of Clachnaben behind

The other site is that of a Miles Master which crashed here in 1941. The wreck site consists of two small debris fields about 70m apart at altitudes of about 390m and 410m, just north of the minor summit of Cairn of Finglenny. The higher debris field contains the single V12 Rolls Royce Kestrel engine from the Master, as well as the propellor hub. The lower debris field contains many mangled metal fuselage panels with yellow painted livery still visible, identifying this aircraft’s role as that of a trainer.

You can see my page about these wreck sites on my website here.

On the return leg of the the walk in the late afternoon, conditions were right for me to catch a glimpse of the planet Venus in full daylight, nearly an hour before sunset. I’ve experienced such excellent seeing conditions once before, allowing me to see Venus in daylight with the naked eye (see my blog posting ‘A Christmas trip to the freezer: Sgor na h-Ulaidh and Spidean Mialach‘).

There were a couple of classroom lectures about about planning winter routes in the mountains and about avalanches in general. The bulk of the day however was spent in a small group on the slopes of the Cairngorms above Glenmore lodge, with some micronavigation and general navigation techniques for winter walking routes and then a climb through some difficult terrain of snow-covered heather to Coire Laogh Mòr to find some deep snow.

There is not as much snow in the Cairngorms at the moment as there has been in the last 2 winters but luckily there has been just enough so far this winter to make yesterday’s course worthwhile. The weather conditions yesterday were quite favourable for the course with only light winds and no snow showers in the afternoon.

In the corrie, the group was shown how the prevailing wind and the topography of the land affects where snow lies and creates areas of potential risk. In the corrie the group practiced cutting blocks in deposited banks of snow on lee slopes to evaluate the snowpack for avalanche risk and to see visually how layers of different types of snow can cause avalanches.

This was a really good complement to the winter skills I course I went on 2 years ago (see my previous blog posting (’Winter skills course‘), covering some things that go beyond the basics.

At Glenmore Lodge there was a grandstand view of a RAF SAR Sea King helicoper landing, refuelling and taking on a Mountain Rescue group and taking off again. The helicopter was active all day as it was taking part in the search for a missing walker in the Larig Ghru.

Whilst staying in Perth the night before the course, I caught a glimpse of a minor display of the northern lights, the first time I have seen a display in many years and a sign of the sun entering an active phase in its 11-year cycle. Other observers got a better view.

The Power of Maps by Denis Wood

Geography is a somewhat schizophrenic discipline. Is it a ’social’ science or is it a ‘hard’ science? The two aspects of the discipline have been in conflict since the ‘quantitative revolution‘ of the 1950s and 1960s within Geography, and the ‘hard’ science of Geography is represented in many respects now by the field of Geographical Information Science (GIS).

Maps are at the very centre of this conflict - what they represent, what their purpose is, how they are constructed and perceived, and what effect they have on society and individuals.

To someone coming from a ‘hard’ science background it can be surprising to read the arguments from the other social science side of the debate. To a ‘hard’ scientist, maps and cartography in general can seem to be self-evidently ’scientific’, rational, objective and just plain useful tools for many purposes: navigation, landscape management & planning and environmental visualisation amongst them. This apparent ‘positive’ aspect of maps is now more widespread and prevalent than it has ever been, with the wholesale integration into modern culture of web-based mapping tools such as Google Earth and Google Maps. To many, the benefits to modern society of mapping are so obvious as to not constitute grounds for serious debate at all. The assumption is that maps are ‘descriptive’ and represent the fruits of positive philosophy and the scientific method - they represent things ‘as they are’.

However, any serious student of GIS should realise that there is another side to this debate, exemplified by the arguments presented in books such as Ground Truth (edited by John Pickles and published in 1995) and The Power of Maps by Denis Wood (published in 1993). The Power of Maps in particular, presents many ideas that may be new to one who assumes that mapping and cartography have been, and continue to be, tools that are used dispassionately and ’scientifically’ to aid society and individuals in general. These books pay attention to another interpretation of mapping - its use for prescriptive or ‘normative‘ ends - how things ‘ought to be’. This inevitably involves politics and power in human society and all the complicated and ‘unscientific’ aspects of this. The ‘descriptive’ or ‘positive’ interpretation of mapping is also subjected to heavy critical analysis.

The Power of Maps is an influential but flawed book. Its style of writing is complex, overly verbose, eccentric and idiosyncratically conversational all at the same time, and is almost illiterate in places. A lot of the content is gobbledygook and several sections of frustrating prose are impossible to interpret and could easily be placed in the Pseuds Corner section of Private Eye.

Wood espouses the ideas of the structuralist philosopher and literary critic Roland Barthes and extends these ideas in the Power of Maps to formulate his own critique of historical and contemporary mapping and cartography, particularly in reference to the signs and symbols used on maps. Unfortunately this approach is responsible for a large amount of unnecessary opacity affecting the core themes of the book making them all but incomprehensible. This is a major weakness of the book, as hidden amongst the impenetrable prose are important ideas about how maps function.

One of these important ideas is the notion of choice. The creation of a map is all about choices; what to put in the map, and what to leave out. This is a necessity, because no map can be an exact replica of the world it portrays (embodied in the notion of the ‘perfect’ map; see below).

Wood updated his ideas about maps in a follow-up book to the Power of Maps, Rethinking the Power of Maps (published in 2010), which ditches much of the distracting and overly philosophical verbiage (or should that be garbage?) of the Power of Maps and is hence much more readable. He also (with Ward Kaiser and Bob Abramms) wrote Seeing Through Maps (first published in 2001), which graphically analyses many examples of different mapping styles and the cartographic and political choices made (particularly in the choice of which projection to use) in the development of each, usefully providing many large pictures of the maps in the book as examples. Edward Tufte’s seminal ‘The Visual Display of Quantitative Information‘ (first published in 1992) also touches on some of the strengths and weaknesses of mapping.

None of these books use colour in their display of the maps discussed in them however (apart from later editions of Tufte’s book), a limitation (presumably imposed by financial contraints) that makes the reader of the books aware of the power and importance of colour in mapping.

My personal viewpoint in this debate is that the arguments of Wood and Pickles should not be ignored but must be confronted and their more obvious and straightforward critiques should be acknowledged and accepted by anybody constructing or using maps. However, it would be wrong to suggest that because of these real problems, mapping and cartography in general and in particular modern web-based mapping tools and GIS software applications are somehow inherently undesirable, socially dangerous and structurally flawed. I don’t believe that they are, and I believe further that their enormous practical utility in diverse areas and profound strength as tools for investigating and analysing the environment outweigh any potential or perceived negative qualities that they may have. One must not fall into the trap when being confronted with the arguments from the social science side of the geographic mapping debate of throwing the baby out with the bathwater.

Quite beyond these issues pointed out from the social science side of the geography debate, there are recognised problems in GIS that have been thrown up from the ‘hard’ science side; namely the ecological fallacy, the modifiable areal unit problem, and the failure of traditional statistical techniques to cope with spatial data (spatial autocorrelation). All GIS students must be aware of these problems, acknowledge them and always work with the limitations they impose in mind.

2. The perfect map

The notion of the ‘perfect’, or 1:1 scale map is one which has been satirised in literature. In the Lewis Carroll story ‘Sylvie and Bruno Concluded‘ published in 1893 (chapter 11, entitled The Man in the Moon) there is the following exchange between the Historian (the narrator of the story) and Mein Herr:

“…What a useful thing a pocket-map is!” I remarked.

“That’s another thing we’ve learned from your Nation”, said Mein Herr, “map-making. But we’ve carried it much further than you. What do you consider the largest map that would be really useful?”

“About six inches to the mile.”

“Only six inches!” exclaimed Mein Herr. “We very soon got to six yards to the mile. Then we tried a hundred yards to the mile. And then came the grandest idea of all! We actually made a map of the country, on the scale of a mile to the mile!”

“Have you used it much?” I enquired.

“It has never been spread out, yet,” said Mein Herr: “the farmers objected: they said it would cover the whole country, and shut out the sunlight! So we now use the country itself, as its own map, and I assure you it does nearly as well…”

Jorge Luis Borges also wrote about this idea in the short story ‘On Exactitude in Science‘ (originally published in 1946). The (very) short story is (in full):

In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast Map was Useless, and not without some Pitilessness was it, that they delivered it up to the Inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography.

A YouTube video can be seen here that uses some still images (some from Google Earth) to visualise the concepts in Borges’ short story; the video contains audio of Borges reading out the story (in Spanish).

The comedian Steven Wright updated this idea for one of his trademark deadpan surreal one-liners:

“I have a map of the United States… actual size. It says, “Scale: 1 mile to 1 mile.” I spent last summer folding it.”

These satirical examples highlight quite effectively that no map is a 100% accurate and precise reflection of reality - all maps are instead abstractions of reality. Indeed, a ‘perfect’ map is an impossible and unattainable objective due to the effects of fractal dimensions in generalisation procedures (see some more examples of this idea explored in literature here).

3. Selectivity in mapping the upland mountain environment

Once one becomes aware of the idea that all maps are the ‘imperfect’ result of unavoidable compromises and that choices have been made in the development of a map, one becomes aware of the selectivity of the features displayed on the map, and the intentions and objectives of the mapmaker become clearer (or perhaps alternatively, more contradictory and confusing).

The most widely used maps in the UK are developed by the Ordnance Survey (OS), the National Mapping Agency of Great Britain (Northern Ireland is not covered by the OS). The OS Landranger and Explorer series of printed paper maps are used for many different purposes by people with differing objectives and they give the appearance of mapping products that are intended to cater for the largest and widest possible range of aims and uses. This inevitably involves compromises and an analysis of how these OS maps display the upland mountain environment of the UK is instructive in showing the effects of these compromises.

One of the important ideas that Wood highlights in the Power of Maps is that there are choices made by mapmakers in displaying topographic features that have a certain ‘temporal stability’. This temporal stability may be explicitly defined, but is more often not. He stresses that, in the temporal extreme, nothing is stable (the Earth will not remain the same for ever) but that some things are stable enough to be displayed on maps. This includes natural physical features such as mountains and rivers, but also artefacts of human society such as towns and roads. Any temporal instability of these things (e.g. a new motorway added to the road network) can be catered for by updates and new editions of the maps. Some things however are too spatially unstable or have attributes that are too impermanent over a selected time period (this period could conceivably be of the order of hours, days, months or even years) to be displayed, such as the locations of individuals or vehicles, river floods or opencast mine workings. Even a digital mapping database of features which is updated regularly (such as the OS MasterMap database; the OS claim that there is a ‘continuous and cyclic revision’ update period of the data layers of 6 weeks) has to draw the line somewhere.

However there are some inconsistencies in the choices that OS mapmakers have made on these maps. Some semi-permanent things which exist in the mountain environment such as bothies, shielings, paths, fences, forest plantations, ruins, cairns, ski slopes, electricity pylons, wind farms and memorials are shown on OS maps, presumably as aids to navigation but also for land management purposes. Some of these structures may only have lifetimes measured in tens of years. Some other things which might also similarly be classed as ’semi-permanent’ are not shown on OS maps at all, or if they are shown are displayed inadequately or unsatisfyingly. Some examples follow:

The area of the summit of Ben Macdui on a OS 1:50,000 Landranger map; click on the image for a larger version

3.1 Aircraft wreck sites

The upland areas of the UK have many sites where aircraft have crashed, and for one reason or another have not been completely cleared away (see my website pages about these sites here). Taken in total, these sites number in the hundreds. Some of the sites contain very large areas of wreckage that have lain at the site for over 60 years; but no OS map shows the location or extent of any of these sites. If a memorial has been constructed at the site of a crash, this is sometimes shown, such as the memorial a few hundred metres to the north-west of the summit of Ben Macdui (the second highest summit in the UK) to the Avro Anson that crashed near the summit in August 1942 (see a screenshot of the OS 1:50,000 Landranger map of the summit area of Ben Macdui to the right; the memorial is marked by a small black empty circle and the world ‘Meml’). However, the wreckage of the aircraft itself (which can in some cases cover an area of several square kilometres) that is marked in some instances by these memorials is not shown on any OS map.

It is difficult to deduce what the rationale is behind this choice. The OS has clearly decided that a memorial (or a cairn) is a permanent ‘feature’ worth mapping but the wreckage itself which has been at the site longer than the memorial and in many cases covers a much larger area with individual pieces much larger than the memorial itself, is not worth mapping. The wreckage has become invisible on the map, but it’s still there nonetheless (see a photo of the Ben Macdui memorial here and a photo of a large piece of the Anson wreckage, about 100m away from the memorial here).

An argument can be made that these sites are essentially assorted debris from ephemeral human activities, on a par with industrial waste sites, and as such to portray their locations on a map would be needlessly pedantic and even petty. However, this argument could also apply to ruined farm buildings, ruined crofting houses and old unused fences and stone walls in the remote glens of Scotland, which are extensively mapped by the OS. Some similar features such as the sites of historical battles are also mapped by the OS, despite there being no physical remains of the battle at the site. The sites of sunken ships are also mapped by the UK Hydrographic Office (although there is a strong practical necessity for this, as potential hazards to shipping).

The River Garry in the area of Dalnacardoch on a OS 1:25,000 Explorer map; click on the image for a larger version

3.2 Controlled and modified rivers

Loch outlines changed by dams and hydroelectric schemes are shown on OS maps, but rivers affected by these same schemes are often not indicated accurately. One example of this is the River Garry in Perthshire which is displayed on the OS map running alongside the A9 road as a fairly large river (see a screenshot of the OS 1:25,000 Explorer map of the River Garry in the Dalnacardoch area to the right); but this depiction of the river as wide (indicated by a ribbon of light blue enclosed by darker blue boundaries) is only true when water is released in a controlled fashion from the upstream hydroelectric scheme at times of high rainfall, snowmelt or to help with downstream salmon spawning (an artificial ‘freshet‘); at most times of the year this river is almost completely dry due to the diversion and abstraction of its waters, and in this temporal respect the OS maps do not show the river accurately. See a website with much information about the current state of the River Garry and photographs of the river here.

3.3 Semi-perennial snowpatches

OS maps also do not show the location and extent of any semi-perennial snowpatches in the Scottish mountains (see my website pages about these features here). An argument can be made that these are only in existence as distinct features in the mountain landscape of Scotland for a few months each year, vary in extent from year to year and hence cannot be mapped usefully or accurately. However, snowpatches in Garbh Choire Mòr, south of Braeriach in the Cairngorm mountains have only completely disappeared 5 times in recorded history (in 1933, 1959, 1996, 2003 and 2006), and then only for a few weeks each time before being replenished with new snow. The snowpatch in Garbh Choire Mòr commonly referred to as the ‘Sphinx’ snowpatch after the climbing route and rock buttress above it, has been estimated to have been in continuous existence except for these 5 short periods of disappearance, totalling perhaps only 4 months in duration, since the ‘Little Ice Age‘ of the 16th to the 19th centuries. For most purposes then, some of these features are essentially ‘permanent’, certainly more permanent than some of the other features mapped in the upland areas of OS maps mentioned above.

What the OS maps do feature prominently however, are placenames, some of which refer to long-lasting snow, such as ‘Cuidhe Chròm’ (meaning the crooked or bent wreath), which refers to a long-lasting snowpatch near the summit of Ben More near Crianlarich (on the OS 1:25000 Explorer map of the area), and a location about 2km to the south-east of the summit of Lochnagar, although this area is not known for holding long-lasting snow and the placename appears to refer to a minor 1083m summit of Lochangar.

There is also ‘Coire an t-Sneachda‘ (meaning corrie of the snow) which is most widely known as referring to one of the corries in the northern corries of the Cairngorms, but there are also others, to the south-east of the summit of Beinn Bhrotain in the Cairngorms, to the south-east of the summit of Toll Creagach between Glen Affric and Glen Cannich, and to the north of the summit of Beinn Mhanach between Bridge of Orchy and Loch Lyon (spelt as ‘Coir an t-Sneachda’ on the OS 1:25000 Explorer map of the area).

The placename ‘Leac an t-Sneachda’ (which appears to mean something like the flat stone/slab/hillside/slope of snow) also appears about 1.5km to the north of the summit of Aonach Mor (on the OS 1:25000 Explorer map of the area). The ski slopes of the Nevis Range ski centre are located here and a long-lasting snowpatch in this corrie is known colloquially as the ‘snow goose‘ due to its remarkable similarity in appearance at certain points of the year (usually the early summer months around June) to the profile of a walking goose (a good photo showing an example of this can be seen here, and also another photo of the snowpatch can be seen here which shows the snowpatch with quite a different shape, but this time recognisably as that of a bird in flight). The restaurant located at the top of the Nevis Range gondola top station at an altitude of about 650m in this corrie is also called the Snowgoose restaurant.

What the OS don’t do is map the extent of the physical features which are referred to by these placenames; the existence of the placenames on the map just exposes the invisibility on the map of these features even more!

Some widely-used snowpatch placenames are not even displayed on OS maps. ‘Cuidhe Chròm’ is also used locally in the area to refer to the long-lasting snowpatch at the head of Coire Cas above the Cairn Gorm ski centre but is not displayed on any OS map. The corrie immediately to the east of the summit of Ben Macdui is unlabelled on any OS map but is widely referred to as ‘the snowy corrie’. A large long-lasting snowpatch on Beinn a’ Bhuird in the Cairngorms is known locally as ‘the laird’s tablecloth’, but again this placename is not displayed on any OS map (it is instead labelled on the OS 1:25000 Explorer map of the area as ‘Lar-choire Sneachdach’ and ‘Ear-choire Sneachdach’, meaning west corrie of the snow and east corrie of the snow, respectively). A snowpatch to the south of Brown Cow Hill in the eastern Cairngorms is known locally as ‘broon coo’s white calf’, but appears on no OS map, and neither does the ‘catskin’ snowpatch in Observatory Gully on the northern face of Ben Nevis and the Lady Alva’s web or veil snowpatch on the Ochil Hills just to the south of the summit of Ben Cleuch (although this snowpatch now appears only rarely, it did appear in the spring of 2010 and lasted until May; there is an article on the Caledonian Mercury website written by Dave Hewitt about this snowpatch and some of the others mentioned in this blog posting here).

The Athabasca Glacier on a 1:50,000 recreational map of the area of the Columbia Icefield in the Canadian Rockies; click on the image for a larger version

It is instructive to see how similar features are mapped in other countries where they exist. Glaciers are mapped prominently in mountainous areas, with the extents and boundaries of the glaciers marked; this is despite the areal extent of many glaciers being anything but permanent from year to year. The Athabasca Glacier, part of the Columbia Icefield on the border between the province of British Columbia and Banff and Jasper National Parks in the province of Alberta in the Canadian Rockies has retreated significantly since exploration (by non-First Nations people) of the area began in the 19th century. A recreational map of the area of the tongue of the Athabasca Glacier (see a scanned image of a section of this map to the right) shows graphically the different extents of the glacier since 1870. It should be stressed that this map is displaying boundaries which no longer exist in reality on the ground. However, on the ground there are marker signs at the foot of the glacier showing where the limits of the glacier used to be (see a photo of the tongue of the glacier and a sign which I took in June 2007 here).

This recreational map was created using topographical data from the Centre for Topographic Information, Natural Resources Canada, the Canadian National Mapping Agency.

The area of the summit of Storronden in Norway on a Statens Kartverk 1:50,000 topographic map; click on the image for a larger version

Smaller features than glaciers, which are more akin to the Scottish semi-perennial snowpatches, are also mapped in the maps of other countries beyond the UK. A good example of this are the Statens Kartverk (the Norwegian National Mapping Agency) 1:50,000 topographic maps of Norway which as well as displaying glaciers, show the locations and extents of smaller ice and snow features which could be described as ‘glaceriets’ or less permanent snowpatches. Storronden, a 2138m mountain in the Rondane National Park region of Norway that I climbed in August 2001, does not contain any glaciers on its eastern face or the Langbotn valley extending eastwards from the summit (see a picture I took in August 2001 from the summit looking down the eastern face here, and an aerial photograph of the mountain and the Langbotn valley here) but does contain many snowpatches, some of which are probably perennial (but perhaps are not composed of true ‘glacial’ ice). This is mapped as a blue area to the east of the summit of Storronden on the Statens Kartverk topographic maps (see a screenshot of the online mapping of the area to the right; this image and the aerial photo above have been taken from norgeskart.no).

3.4 Harvey maps

The area of Coire an t-Sneachda in the northern corries of the Cairngorms on a Harvey 1:40,000 map; click on the image for a larger version

This inconsistent selectivity of features in the upland environment is not restricted in the UK to maps created by the Ordnance Survey; Harvey maps, although aimed primarily at people using the outdoors for recreation, such as hillwalkers and rock climbers, display choices that are just as selective and subjective as those of the Ordnance Survey. They show relatively small features such as individual large boulders in mountain areas (see a screenshot of a 1:40,000 Harvey map of the Coire an t-Sneachda area of the northern corries of the Cairngorms to the right, showing a boulder a few metres across that is used by rockclimbers for bouldering, visible as a small black filled circle below the ‘t’ of the Coire an t-Sneachda placename), but do not give any indication of the locations and extent of aircraft wreckage or semi-perennial snowpatches.

4. The map is not the territory; beyond mapping

When (for example) planning a walking route in the mountains, or whilst actually in the process of navigating a way through a remote mountain environment, it is all to easy to visualise the unseen sections of the route in your head using the map and fall into the trap of assuming that this mental visualisation is an exact replica of reality. This can potentially lead to surprises and missed opportunities (or worse) when the reality conflicts with the visualisation.

‘The map is not the territory‘ is a phrase that is often used to describe this problem, and indeed neatly labels all the various issues of knowledge discordance detailed in this blog posting. This phrase was first used in print in a paper written by Alfred Korzybski in 1931. The phrase ‘ground truth‘ (often used in the context of military strategy and tactics) can refer to the same concept.

The idea behind ‘the map is not the territory’ can however be extended beyond the disciplines of cartography and geography to the limits of knowledge itself. Creative thinkers as diverse as the surrealist painter René Magritte and the writers Laurence Sterne, Robert Pirsig and Neil Gaiman have explored this idea. The philosopher Alfred North Whitehead called it the ‘fallacy of misplaced correctness‘, which happens when an abstraction (a map being just one example) is mistaken for physical reality.

Borges, as well as his short story ‘On Exactitude in Science’, wrote a short story entitled ‘The Library of Babel‘ (originally published in 1941). In this story Borges imagines a library so vast and authoritative that it contains books with every single combination and permutation of characters; hence while the large majority of books in this practically and essentially (although perhaps not philosophically and mathematically) infinite library contain nonsense, there must be a subset of books within the library that collectively contain all possible knowledge.

Borges in some respects foresaw and envisaged the potential of the modern Internet and World Wide Web. The essential difference between Borges’ library and the Internet however, is that Borges’ library was rendered useless by the impossibility of indexing and hence finding anything useful in the library, whilst with the Internet there are search engines that attempt to carry out this herculean (or perhaps sisyphean?) task of indexing the entire Internet.

The attempt by search engines such as Google to index the entire Internet and websites such as Wikipedia to describe in detail all possible topics can be extrapolated to a fantastical level with the concept of an online digital library of all possible knowledge, indexed and accessible to all; however it is a trap that can be surprisingly easy to fall into to believe that this fantastic and improbable goal has somehow already been achieved by the enormous scale of the current Internet; just as the map is not the territory, Google is not the universe (or all knowledge).

Many sources of knowledge, information and data still lie beyond the grasp of Google. These include undigitised texts, images and objects (old-fashioned libraries of books and journals, archives and museums), and the ‘dark web‘ of databases that are not indexed by Google due to their being hidden behind security, authentication or payment barriers, not accessible by web-based communication protocols (e.g. Z39.50 databases) or not even physically connected to the Internet.

Indeed, the very terms ‘Internet’ and ‘World Wide Web’, whilst very often used interchangeably as synonyms, nevertheless are labels for different things; the World Wide Web (the specifications and protocols for which were developed by Tim Berners-Lee at CERN in 1990) is just the most visible subset of the much larger Internet (which was developed by DARPA in the 1960s). Much data, content and services which are part of the Internet are not part of the World Wide Web, e.g. emails, instant messaging, FTP servers, P2P file sharing and videoconferencing. Google does not index this.

However, this discrepancy between the map (the Internet) and the territory (all knowledge or information) is reducing as every day goes by. How close Borges’ fictional Library of Babel is approached by this seemingly inexorable process in the future is virtually impossible to predict.

A snow book, northern Scotland, by Adam Watson

Adam Watson has been continuously observing and collecting data about snow in the north-east of Scotland (and particularly in the Cairngorm mountains) since the 1930s, and this important book represents the culmination of that activity. It will have a strong claim in the future to being the standard reference work in the discipline of research into and observation of long-lasting snowpatches and snow-cover in general in the Scottish mountains.

The first five chapters contain the ‘meat’ of the book. These chapters are in the format of academic papers and present and summarise all the data gained from a century of observation of snowpatches throughout the Scottish mountains (by many observers as well as Adam), along with statistical analyses and conclusions about any possible historical trends and correlations. Topics covered include observations of snow cover and snowfalls in summer and autumn, and the persistence or survival of snowpatches until late into the year.

The subsequent chapters are slightly less formal and contain Adam’s many observations, photographs and conclusions concerning various snow-related features in the mountain areas of Scotland, including whether glaciers existed recently in the Cairngorm mountains, avalanches, animal behaviour in snow and the effect of snow cover on rock lichens.

The large format of the book allows for the inclusion in detail of many full-page photographs from Adam’s extensive collection (the large majority in colour) supporting the data and observations in the accompanying text.

Along with ‘Cool Britannia’ (written by Adam in collaboration with Iain Cameron; see my previous blog posting ‘Cool Britannia‘ for a review of this) which was published in 2010, these books represent a valuable archive of data about snowpatches in the Scottish mountains, as well as representing the most up-to-date contemporary research into this discipline. All of the available data from Adam’s substantial 70-year long observing record is summarised and collated, as well as data from all other relevant sources. Full lists of citations are given to all relevant earlier published work, making this book now the most authoritative and reliable reference source material available anywhere for any future discussions and investigations concerning snowpatches in the Scottish mountains or indeed the Scottish mountain environment and climate in general.

These two books are the foundation upon which any future observations of, and research into, snowpatches in Scotland will be built, and Adam is to be congratulated on publishing this work in publicly available books, rather than hidden away in subscription-only academic journals. Although some may be uncomfortable with the fact that the more formally rigorous and traditional academic peer-review process has been bypassed with this material, the scientific quality and value of the content appears to be very high. Opening this data to all eyes means that it is also now possible for anyone to question and judge its merit (a good thing in my opinion), and use as the basis for further academic research. This openness may well also be a more valuable way of stimulating wider and further observation and recording of snowpatches by amateurs in the future (an example of ‘citizen science’; see my previous blog posting ‘The new world of scientific research on the web‘).

This book is intended for a specialist and academically-orientated audience, for which it is invaluable, but anyone with an interest in how snow affects the environment of the Scottish mountains will find this book interesting.

It's a fine Day for the hill, by Adam Watson

Adam Watson can surely lay claim to being a true ‘Mountain Man’ of Scotland - perhaps the premier contemporary claimant to this auspicious title!

Adam Watson’s recently published ‘It’s a fine day for the hill‘ (subtitled ‘And once in a blue sun and moon’, the meaning of which is explained in the book) is his personal memoir of mountain exploits (especially in the Cairngorm and Mounth regions of the Scottish mountains) in the years from the 1940s to the early 1960s and the people he has known. In his time he has been a young amateur naturalist, a gillie, a student and researcher, a bird-watcher, a hillwalker, a rock climber, a mountaineer, a cross-country skier, a writer and an environmental scientist.

Perhaps the most interesting sections of the book are those that detail his close friendships with four individuals who have become icons in the history of the various types of activities that have been carried out by people in the mountains of Scotland in the 20th century, and are also well-described as ‘Mountain Men’: Seton Gordon, Bob Scott, Tom Weir and Tom Patey.

It is fascinating for modern readers who are perhaps only familiar with the places talked about in this book (particularly the Cairngorms) as hillwalkers to see how places like Rothiemurchus and Glen Lui used to be, before they changed from managed and farmed estates to the walking and skiing playgrounds, national parks and nature reserves they are today.

Particularly captivating are his accounts of youthful and penniless expeditions to Iceland and Norway (a much more serious undertaking in the days before cheap air travel and organised tourism) and long-distance solo cross-country skiing expeditions across the Cairngorm mountains, when this was still an entirely novel (and potentially dangerous) undertaking.

Adam Watson shows with many examples of his youthful exploits in the mountains in this book his personal philosophy of exploring and adventure, which is that “Exploration by one’s own free will is best pervaded by humility and wonder” and “Those who behave as if alone on an icecap when nobody else knows where they are and no help is possible, have greater inherent safety”.

Many things have changed since the years recorded in this book, in particular his individualism and self-reliance is somewhat out of fashion and counter to prevailing contemporary ideology that seems to stress safety and human-centred nanny-state ‘management’ above all else - perhaps to the detriment of the experience of the outdoors.

Other things give an indication of changed times and attitudes, particularly his recounting of raiding birds’ nests for eggs whilst a boy and on a trip to Iceland whilst a teenager, and also his almost casual accounts of Bob Scott shooting goosanders, foxes and a wild cat in Glen Lui. Within the circumstances of the time (the years of the Second World War and directly afterwards) these were not irresponsible and ill-informed activities but to modern sensibilities they might be surprising.

The large format of the book allows for the inclusion of many photographs from Adam’s collection, many unusual in being in colour and of high quality, from an era before taking cameras into the Scottish mountains was common.

The author at the An Cùl Choire snowpatch on Aonach Beag in October 2010

One of my pet interests is the study of long-lasting (and sometimes ‘perennial’) snowpatches in the Scottish mountains. I have written many previous postings on my blog on this subject (see a list of these on my website here).

The question of what factors affect the longevity of snowpatches in the Scottish mountains through the summer and autumn seasons, and potentially until they are covered permanently by the snow of a subsequent winter (making them ‘perennial’), is one which has been discussed at some length in the relevant academic and scientific literature since the early 20th century (see a complete list of these references on my website here). Simply put, these factors are many and varied, but include:

• short-term prevailing meteorological (’weather’) trends over the preceding months, particularly the winter months, but also the spring and summer months - these trends are: precipitation (volume of accumulated snowfall), average air temperatures, freeze/thaw cycles (which consolidate any snowpack making it more resistant to melting), effective hours of sunlight and cloud cover, and prevailing wind direction and strength [13]
• latitude and altitude [16], [17]
• local or adjacent topography (e.g. slope angle, slope aspect, upwind snow-gathering plateau areas or ‘fetch’ and sheltered depressions or hollows) [13]
• vegetation - this is largely due to high altitude tree cover and does not apply in upland areas of the British Isles, but is a factor in places like the European Alps or the North American Rocky Mountains [4], [6]
• highly localised factors such as snow avalanches in the winter months, rockfall, streams, ground composition (bare rock and soil insulate the snow differently) and snow surface coverings (such as windblown grass and soil) [1]
• human factors; it has been speculated that snowholes dug into snowbanks during the winter months for winter mountaineering skills courses may accelerate melting of the snow; this has been suggested for the Ciste Mhearad and Coire Domhain snowpatches on the Cairngorm plateau - also the ski fences erected in Coire Cas in the early 70s for the Cairn Gorm ski centre may have reduced the depth of snow in areas that held long-lasting snowpatches previous to the construction of the ski slopes in the area [1]

The effect of long-term climate trends on long-lasting snowpatches in the Scottish mountains is currently a matter of much debate. Whether measurements of these snowpatches can be used as reliable indicators of global climate change is uncertain and beyond the scope of what I am discussing in this blog post (see a BBC website news article from June 2008 here highlighting some SNH research into this). Adam Watson has been collecting data on Scottish snowpatches since the 1930s, and this rich dataset has recently (2011) been published in full along with Adam’s statistical analyses of this data (and data from other sources) and conclusions about trends [1]. This data provides the most useful source of any potential future analysis correlating the temporal and spatial distribution of snowpatches in the Scottish mountains with historic climate variation (at least over the past century or so).

The second of these factors, latitude and altitude, I discussed in some detail in my previous blog posting ‘The Scottish mountains: on the glacial ‘knife-edge’‘).

The third of these factors is one which particularly interests me, and which I believe has not been studied in great detail before in the context of snowpatch survival; most scientific research related to this subject has involved the study of glaciers beyond Scotland and also of glaciers in Scotland during the last ice-age. Much of this research has also focused on the first of the factors listed above (meteorological) and wind-drifted snow, rather than on purely topographical factors [8], [9], [10], [13].

I believe that there is scope in using GIS (Geographical Information Systems or Science)-based topographic analysis techniques to build on this research to study and analyse the topography of long-lasting contemporary (i.e. since modern useful recording and measurements began in the 20th century) snowpatch areas in the Scottish mountains, which may well prove to be a fruitful area of future research and provide useful results.

Many primary topographical attributes (such as altitude, slope aspect, slope angle, upslope slope, upslope height, upslope area, profile curvature and plan curvature) can be obtained and derived from a DEM (Digital Elevation Model), which are relevant to the locations of long-lasting snowpatches [14].

The dependency of a particular, significant and recorded snowpatch location on these attributes can be modelled using GIS and statistical software to discover any significant correlations. Hence the observed and measured spatial distribution of long-lasting snowpatches can perhaps be explained, modelled (using regression analysis) and predicted to some degree [6], [7], [13].

Unlike meteorological factors, topographical factors are relatively constant through time periods in their influence on the spatial distribution of snow, and hence are simpler to model.

In particular, GIS techniques can be used to model the effect of sunlight on snowpatch areas and calculate any dependencies on local topographical attributes affecting that sunlight (and here adjacency and proximity must be defined according to sensible criteria; a maximum distance of 10km from the location under analysis is used in [5]). This can be done by using GIS software such as ArcGIS, which can calculate the total amount of annual solar radiation (or more precisely, irradiance or insolation) on a particular location [12].

Example direct solar radiation viewshed map for a single 24-hour period; purple represents area receiving 7.68 hours of sunlight (maximum), blue represents 3.6 hours of sunlight (minimum). Image from http://freegeographytools.com/

Given DEM data for a given location (including primarily latitude and altitude data), ArcGIS can calculate the total amount of time direct solar radiation is incident on that point over an annual season cycle, taking account of shading from local topography (within a specified distance), and also taking account of indirect radiation (i.e. ‘diffuse’ scattered sunlight and reflections from surrounding topography) to produce a cumulative intervisibility ‘viewshed‘ map for that location [18], [19], see example to the right.

This technique requires plenty of computer processing power and access to high-quality, accurate and high-resolution DEM data of the area being analysed. The time interval and maximum distance from the location (or ‘viewpoint’) chosen to analyse the data has an important effect; smaller time intervals and larger distances give more accurate results, but have a proportionate influence on computational complexity and processing speed. A time interval of 30 minutes giving a reasonable level of accuracy is specified in [12].

LiDAR data represents the ideal DEM data for this technique, although availability and coverage of this data for the area of the Scottish mountains is something that would require investigation. OS DEM data (Land-Form Profile) is available at a resolution of 10m for the whole of Great Britain, which may be of a high enough resolution to obtain useful results. Unfortunately the higher resolution OS DEM data (Land-Form PROFILE Plus), which is derived from LiDAR data, is only currently available for selected parts of England and Wales.

This technique is already used in other contexts such as urban planning, solar energy planning and agriculture but it is still relatively under-utilised in the analysis of snow cover in upland environments, and has not been applied to mountain environments in the British Isles (but see [4], [9] for examples from Glacier National Park, Montana, USA, [7] for an example from Idaho, USA, and [2], [6] for examples from the Swiss and Italian Alps respectively, which use GIS techniques to analyse and model the effect of topography on snow cover and snow depth in a mountain environment).

One long-lasting snowpatch which demonstrates the potential utility of this technique is the An Cùl Choire snowpatch below the north face of Aonach Beag in Lochaber (see my website page about this snowpatch here). The An Cùl Choire snowpatch is unusual in being at such a low altitude (about 920m, 300m lower than the summit of Aonach Beag), and strangely, having gone largely unnoticed and unreported until the last decade despite being visible from the main walking route between Aonach Mòr and Aonach Beag [1, and the author's personal observations]. This may well be because the snowpatch looks uncannily similar to large areas of quartz outcrops in the corrie, especially from a distance, and casual walkers may well have seen it many times but not realised that it was a long-lasting patch of snow.

An Cùl Choire has a distinct topography which may well contribute to the survival of snow within it well into autumn and often into the winter of the subsequent year - the southern wall of the corrie rises up so steeply that any snow lying at the base of this wall to the north sees very little direct sunlight throughout the entire year, even in midsummer. How much annual radiation it actually receives can be calculated using the GIS techniques described above.

I had wondered if the An Cùl Choire snowpatch was in a location that never received any direct sunlight even in midsummer, although a photograph of Aonach Beag on Flickr here taken on July 24th 2011, proves that it does, and must receive sunlight at least 1 month either side of the midsummer solstice.

Another location which has a similar topography to An Cùl Choire is Garbh Choire Mòr, south of the summit of Braeriach in the Cairngom mountains at an altitude of about 1140m. This location contains the most persistent snowpatch in the British Isles, called the ‘Sphinx’ patch, which is surrounded by steep cliffs to the south, west and north. This snowpatch has only melted completely five times since recorded observations began at the end of the 18th century, in 1933, 1959, 1996, 2003 and 2006 [3].

These two long-lasting snowpatch locations are good candidate targets for analysis with the GIS techniques outlined here. Other candidate locations are on the north face of Ben Nevis, and there are many more throughout the Scottish mountains although the majority of the most persistent snowpatch locations are in Lochaber and the Cairngorm mountains [5].

One advantage of using the GIS techniques outlined here to calculate the amount of total annual solar radiation a location gets is that it provides quantitative results that can be used for rigorous scientific and statistical analysis, rather than qualitative results obtained from manual observations and photographic records.

Another advantage of using these GIS techniques (which ultimately rely on DEM datasets derived from data obtained using primarily remote-sensing methods such as airborne LiDAR and satellite-based radar) is that these locations are often inaccessible or obscured from view (due to difficult terrain or weather conditions) and hence not amenable to providing a consistent and long timebase duration of data gathered by on-site manual observations in the field, a necessary requirement for calculating total annual solar radiation.

The combination of remote sensing and GIS techniques is potentially a very productive one for analysing the mountain environment [4], [9], [11]; however the availability and usefulness of passive multispectral natural radiation remote sensing imagery for differentiating, classifying and analysing snowpatches [15] in the Scottish mountains is uncertain. For the image data to be useful for snow cover classification in the case of Scottish mountain snowpatches, it must have high enough spatial resolution (so that snowpatch features of the order of 10m in scale can be differentiated) and temporal resolution (to cover annual, seasonal and monthly variation), and also adequate high-quality (i.e. no cloud cover) coverage of the areas under analysis. Satellite-based remote sensing data such as Landsat and ASTER data may not meet these requirements (the CEH Land Cover Map of Britain, derived from Landsat Thematic Mapper imagery, does not include a classification for snow cover, and has a resolution of 25m). Thus primary empirical data gathered in the field and from secondary sources such as DEM datasets (derived from radar-based active remote sensing technologies such as LiDAR) may be the only practical way to analyse and model Scottish snowpatches quantitatively.

Gathering reliable and scientifically useful data of this sort on field trips into the Scottish mountains is difficult, as shown in an example given by Adam Watson (author of [1] and joint author of [3], [5], [13]), the acknowledged authority on recording data on snowpatches in the Scottish mountains (quote taken from a posting to the Winterhighland website discussion forum on 28th July 2011):

“I have some visual observations for Garbh Choire Mor in a few months in late summer and autumn, which show that the Pinnacles patch gets sunshine later in the day than the Sphinx one. The observations reveal when the sun passes from Sphinx and then a while later from Pinnacles. Of course they refer only to those dates [my emphasis]….The extent to which the perennial patches are shaded by cliffs has been exaggerated in past writings. It makes a better story to emphasise the gloomy cliffs and shaded patches! I always thought the perennial patch at An Cul Choire of Aonach Beag must be in full sunshine for hours in the morning during high summer, when the sun rises approximately in the north-east. I think this would apply also to the Observatory and even more so the Point Five patches. An interesting exception might be the patches right into the gully of Gardyloo, but of course they never attain a great size because of the narrowness of the gully and the steepness. Nevertheless they are remarkably persistent despite their small size and depth.”

There are two factors which should be taken into consideration in drawing any conclusions from the use of these GIS techniques to analyse the effect of solar radiation though:

• there is no allowance for the variation of solar radiation by atmospheric conditions (i.e. clouds, haze and fog)
• solar radiation is not the primary factor influencing snowpatch longevity, despite what one might think intuitively; current research suggests prevailing wind direction in the preceding winter months is more strongly related to longevity. Solar radiation is also almost certainly not the primary topographically-related factor; this is probably snow accumulation caused by wind-drifted snow which is affected by topographical factors such as a large plateau adjacent to a downwind depression [10], [13]

References:

[1] Watson A. 2011. A snow book, northern Scotland. Paragon Publishing.

[2] Schmidt S. 2010. Snow Cover Duration in Relation to Topography in the Loetschental, Switzerland. Landform - Structure, Evolution, Process Control: Proceedings of the International Symposium on Landform organised by the Research Training Group 437. 151-164.

[3] Watson A, Duncan D, Pottie J. 2007. No Scottish snow survives until winter 2006/07. Weather 62. 71–73.

[4] Geddes C A, Brown D G, Fagre D B. 2005. Topography and vegetation as predictors of snow water equivalent across the alpine treeline ecotone at Lee Ridge, Glacier National Park, Montana, U.S.A. Arctic, Antarctic and Alpine Research 37. 197-205.

[5] Watson A, Davison R W, Pottie J. 2002. Snow patches lasting until winter in north-east Scotland in 1971-2000. Weather 57. 374-385.

[6] Tappeiner U, Tappeiner G, Aschenwald J, Tasser E, Ostendorf B. 2001. GIS-based modelling of spatial pattern of snow cover duration in an alpine area. Ecological Modelling 138. 265–275.

[7] Chang K-T, Li Z. 2000. Modelling snow accumulation with a geographic information system. International Journal of Geographical Information Science 14. 693-707.

[8] Purves R S, Mackaness W A, Sugden D E. 1999. An approach to modelling the impact of snow drift on glaciation in the Cairngorm Mountains, Scotland. Journal of Quaternary Science 14. 313-321.

[9] Allen T R. 1998. Topographic context of glaciers and perennial snowfields, Glacier National Park, Montana. Geomorphology 21. 207-216.

[10] Purves R S, Barton J S, Mackeness W A, Sugden D E. 1998. The development of a rule-based spatial model of wind transport and deposition of snow. Annals of Glaciology 26. 197-202.

[11] Walsh S J, Butler D R, Malanson G P. 1998. An overview of scale, pattern, process relationships in geomorphology: a remote sensing and GIS perspective. Geomorphology 21. 183-205.

[12] Kumar L, Skidmore A K, Knowles E. 1997. Modelling topographic variation in solar radiation in a GIS environment. International Journal of Geographical Information Science 11. 475-497.

[13] Watson A, Davison R W, French D. D. 1994. Summer snow patches and climate in northeast Scotland. U.K. Arctic and Alpine Research 26. 141-151.

[14] Moore I D, Grayson R B, Ladson A R. 1991. Digital terrain modelling: a review of hydrological, geomorphological and biological applications. Hydrological Processes 5. 3–30.

[15] Dozier J. 1989. Spectral signature of alpine snow cover from the Landsat Thematic Mapper. Remote sensing of Environment 28. 9 - 22.

[16] Lockwood J G. 1982. Snow and ice balance in Britain at the present time, and during the last glacial maximum and late glacial periods. Journal of Climatology 2. 209–231.

[17] Manley G. 1975. Fluctuations of snowfall and persistence of snow cover in marginal-oceanic climates. Proceedings of the WMO/IAMAP Symposium on Long-term Climatic Fluctuations. WMO No. 421. 183-188

[18] ArcGIS Solar radiation analysis sample applications: http://webhelp.esri.com/arcgiSDEsktop/9.3/index.cfm?TopicName=Solar_radiation_analysis_sample_applications

[19] ArcGIS Solar radiation analysis references: http://webhelp.esri.com/arcgiSDEsktop/9.3/index.cfm?TopicName=Solar_radiation_analysis_references