The story of the Sussex avalanche.
Do avalanches happen in Scotland? This question has been levelled at me a number of times, usually with the assistance of a pair of raised eyebrows. The answer of course is yes, we do, hundreds of them in a year. Most of them go unseen, leaving a debris tip as proof of their existence. All that’s required is a slope with some snow on it for the potential avalanche.
Nonetheless it is surprising that the most devastating occurrence happened not in the snowy Highlands of Scotland, nor the English Lake District, but the definitely un-mountainous Sussex.
The slope above South Street
In 1836 Lewes on the banks of the river Ouse grew on the back of iron and ship building, a busy county town nestled inside a gap in the South Downs. Near present day South Street a string of wooden cottages, known as Boulder Row, had been erected to house construction workers at the nearby sawmill, along with the poor and sick ensconced there by the parish. All along this site rises a 40 degree slope some 60 metres high, beyond which lies the local high point of Cliffe Hill. In December of that year a huge cyclonic snow storm hammered north western Europe and put down several feet of wind blown snow, forming a huge accumulation complete with cornice on the embankment. This had not gone unnoticed, in fact the townsfolk were conscious of the threat and advised the residents of Boulder Row to evacuate, but for reasons of their own they did not.
Several avalanches came down in the area, damaging property and supposedly propelling part of the saw mill and it’s machinery into the river.
Above the Snow Drop Inn, which now stands at the site of the avalanche.
The main event, however, happened on December the 27th at approximately 10.15 am when the whole slope shed it’s snow, engulfing the cottages. The Sussex Weekly Advertiser reported the testimony of an eyewitness who stated "the mass appeared to strike the houses first at the base, heaving them upwards, and then breaking over them like a gigantic wave. There was nothing but a mound of pure white.” No one could be entirely sure how many people had lived there; 7 were pulled alive from the debris and a further 8 or 9 pulled out dead from hypothermia or asphyxia and most probably traumatic injury. The single most catastrophic avalanche event in recorded British history.
A painting of the aftermath, by an unknown artist.
Destruction of property, let alone life, is not something we are accustomed to in the UK. But in alpine countries it’s a hazard that threatens life and infrastructure every winter. Between 1950 and 2000 Switzerland spent €1 billion on avalanche defences, not including protective forestry. In the 40 year period 1970 to 2010 the Swiss had 2239 avalanches in which 4619 people were caught and of these 898 were killed. Thats around 22 per year. A significant number of these people died in buildings because of the large populations living on or in proximity to very large slopes. British mountain geography is very different, not only physically but demographically. Because the harsh, acidic uplands are less useful for arable crops Highland populations established in the glens, and anyway, our snow packs are much smaller, rarely reaching infrastructure, but certainly a hazard for mountain sports goers.
A small slope slab avalanche triggered by a skier.
In Scotland we have the Scottish Avalanche Information Service, which began as the Scottish Avalanche Project in 1988. Every day during the snowy months their forecasters go out and examine the conditions which they use to create an estimation of the situation for the next day. This has now become an essential planning tool for winter hill people. Normally they are not focussed on network infrastructure, such as roads and railways, but in March 2010 they were asked by Network Rail to inspect and make an assessment of the slopes of Beinn Odhar above Tyndrum. A number of slides had come down across the line, but other channeling features had not avalanched. The snow packs in the starting zone of the remaining paths was identified as unstable, so the decision was taken to clear the slope with explosives. A tactic probably never before used to safe guard infrastructure in the UK, but common place in the Alps.
The west coast line struck by avalanche near Tyndrum during the winter of 2010.
I have one particularly salient experience of avalanche in my mountaineering career, a day punctuated by disaster. February 2010 had seen long periods of high pressure, giving bitterly cold nights and sunny, windless days. In these conditions a thick carpet of surface hoar crystals grew up from the snow, which is quite a beautiful thing to see, but can become deadly in some circumstances. Wednesday the 24th was one of these. For the first time in weeks a frontal system with strong winds was due. Myself and a friend, knowing what was coming, used the forecasted time line to plan a quick route on the minus face of Ben Nevis and then escape before the afternoon storm. We knew that the wind would scour up the hoar crystals off the windward mountain slopes and pound them down in sheltered lee slopes, on top of the delicate, undisturbed layer of frost remaining. A big heavy pack of smashed up snow crystals primed on top of a brittle sliding layer.
As we walked up the Alt a Mhuillin path the wind was already up and shifting snow around. Plaques of wind slab broke away around our feet. Given that this was at less than 500m altitude, it was obvious the situation higher on the mountain was already too hazardous, so we reverted to plan B like good mountaineers. An RAF party retreating out on the path spoke of being avalanched on the slopes below the western side of the Douglas Boulder. Another instructor friend was also bailing. Al and I made for the steep cascade of ice that in cold winters forms to the west of the CIC hut, on the basis that we could get to it safely. On the way across I was extremely surprised to find myself smoothly moving sideways, as if on a magic carpet. It took a second or two to realise that we were in an avalanche! I flung my walking poles and rolled my way out. In fact the slide had stopped. Al and I regarded each other with astonishment, obviously we’d had a fright, but was was more surprising was the low angle of the slope. A generalisation suggests that most avalanches occur on slopes of between 30 and 45 degrees gradient, this was definitely shallower. In fact with a bit of impromptu measuring we reckoned about 18 degrees, so testament to how much of a hair trigger the wind slab sat on! By the time we were climbing our route the wind was knocking seven bells out of everything and it was difficult to see each other, let alone hear. Around this time I was aware of an RAF Sea King helicopter flying around the crags; it was so noisy that I didn’t notice it’s persistent activity a couple of hundred metres down slope from us, I assumed it was involved in a training exercise, perhaps with some of the personnel we had met earlier. One pitch of ice was enough and we fled. On the way we met another pal who told us of the drama recently unfolded below Carn Dearg Buttress. A fellow from North Wales had been walking across the top of these slopes and had triggered a slab slide which took him fast down over a steep boulder field to his terrible injury. Our mate had never seen anyone in such a mess and was badly shaken, being the first on scene he had dealt with stabilising the man and basically keeping him alive until evacuation. To be honest the whole atmosphere was a bit doom laden. A similar meteorological situation had arisen earlier in the winter resulting in casualties and I wondered how many other people were out in the hills. At exactly the same time I arrived in my driveway at home I heard my rescue radio crackle, I couldn’t make out the transmission though. A few seconds later my phone rang with callout details: people avalanched on Buachaille Etive Mor. I must admit that, cynically, I cursed the people for descending into Coire na Tulaich, an obvious avalanche trap, I just assumed that this was the case. It was not however. When I arrived at ‘Paraffin Liz’s’ before the Laggangarbh bend police and the rescue team were parked up and rescuers had set off under the west face of the Buachaille massif. It turned out that a Mountain Instructor had been guiding a client on Curved Ridge and was using the high ground bounding Coire na Tulaich as an alternative, safe, descent rather than venture down the Tulaich headwall, which covering all the northerly aspects and rearing above a system of gullies is a notorious avalanche blackspot. The two men stepped onto a small plaque of windslab, which slid and took them several hundred metres down into the Lairig Gartain. Both were killed as a result of their injuries received during the fall. When I arrived at the scene they were being placed aboard stretchers having being removed from partial burial in the avalanche tip. We took them out from foul weather, now black and blizzarding. I never got involved with discussions about rescue events but on this occasion I did. It was reported widely in the online and mainstream press that the mountaineers had blundered into Coire na Tulaich and been taken away by avalanche there, but of course this was not true. Not only was it a slight a slight on the victims’ decision making but also very misleading, the commonly regarded ‘safe descent’ was not infallible. The accident had occurred despite sound decision making and I felt it was important for this information to disseminate.
Coire na Tulaich on Buchaille Etive Mor, the 'safe descent' spur on the right.
A slab released at the coire headwall has driven this large slide into what is a prominent terrain trap.
The terrain trap principle.
A series of heavy winters and a degree of attitude change has brought snowpack safety into a much greater level of consciousness than previously. We don’t have ‘the annual carnage’, as one commentator put it, that perhaps the Alps do. But the potential is there. If all the effort and learning, funding from SportScotland and even the lurid headlines save one life, then it’s worth it.
It's not all doom out there! Photo kindly from Jamie Hageman.