How far did the Devil’s Point stretch?
It’s an odd question, but one that occurred to me one day as I sat on the side of Ben MacDui looking across Glen Dee at the rocky face of Bod an Deamhain, chopped off almost cleanly by the irresistible force of a glacier, where once it must have continued eastwards to… Where?
An instinct to symmetry would suggest it stretching out to link with Carn a Mhaim. Even if the glacier had shaved rather than bulldozed, it must have reached a good way across the current glen. Of course you could argue that it may well have. There needn’t have been a massive hollow behind it: perhaps the glacier was so powerful it trenched out the whole glen in a oner. But then what about Coire Odhar, whose position and shape surely argues for its existence prior to the glacier which gouged out the Dee? It seems a classic hanging corrie after all.
You can ponder this while looking at the map, but how much more powerful a mind venture it is when you sit on the hillside (even in the snow) and try to visualise the mountains as they were, the all-enveloping icefields, the valley-forming glaciers and the smaller corrie glaciers, the plucking of bedrock, the tumbling of whole mountainsides, the bulldozing of debris, the glacial dams and lakes, the gradual and sudden changes effected by water, by freeze-thaw cycles. Add the massive timescales and the mystery of what sequence it all happened in and you have endless source of contemplation.
I’ll come clean before you’re troubled to read any further under false expectations: I don’t know how far towards Carn a Mhaim the Devil’s Point extended; I don’t even know if there’s anyone who does know. There’s a lot written about geology and the hills, about glaciology and geomorphology, but it makes my brain hurt and I retain only tantalising fragments. What I would dearly love is for someone to make one of those computer animations which shows the sequence of the Cairngorms’ formation and evolution through geological upheaval and multiple ice ages. I doubt such a thing is possible, but I crave it.
But even those tantalising traces we are left with – those indications of what must or might have been – provide fuel for wonder. In solitary wanderings I can find myself stopped in long reveries, emerging perhaps none the wiser but much the richer in awe and depth of appreciation of these mountains I love.
And even beyond the obvious glens and corries there’s a lot to see: so many features which hint at the deep history of these hills and, even without full comprehension, add to understanding and to the pleasure of being there.
I’ve read a thesis which talks of a glacial lake in what’s now the Corrour Bothy stretch of Glen Dee, dammed in between ice flowing from the Garbh Choire in the north and from Glen Geusachan in the south. Imagine such a thing!
Maybe easier to visualise is the great loch that must once have occupied Glen Derry. The area referred to as the Derry Dam refers to two dams – one historic and dating back to the logging days of the 1800s, and the other far into prehistory when a glacier bulldozed a great rampart of sand and rock which is still there and which held back a lake whose extent can still be seen in the large flat area of the glen.
The lake eventually drained when its outflow wore a way down through the body of the dam – the course taken yet by the Derry Burn. Indeed, when Sandy Davidson created his own dam there in the 1800s he was just blocking the breach in the glacial dam and recreating a tiny fraction of the original lake.
But there’s another lake whose traces can be seen in Glen Derry, reaching down into Glen Lui and up into Glen Luibeg. If you stand on the higher part of the path up the east side of Glen Derry you can see a faint line in the hillside of Carn Crom – a horizontal fault-like line which runs southward out of Coire na Saobhaidh. Look further and you can see a continuation of the line, faint but discernible, along the side of Sgor Dubh, across on the other side of Glen Lui. And if you head round the corner past the Derry Flats and into Glen Luibeg, you can look up and see the same line picked out along the slopes of Coire Craobh an Oir.
I’d always assumed this to just some quirk of geology, but the same thesis (by Matthew Richard Standell at Loughborough University in 2014) says these lines in the landscape are relic of the shoreline of an ancient lake far more vast than that once behind the Derry Dam. Indeed, while trying in awe to visualise this mega-loch, consider that the pass of Clais Fhearnaig, between Glen Lui and Glen Quoich, was created as the outflow of this loch which once drained into Glen Quoich rather than down the present course of Glen Lui, which would have been blocked still with ice.
How long ago? Well long enough to make your brain hurt, because there are other traces of glaciers past which to my small mind at least must have come much later – in fact Glen Lui (as with the other glens) is full of them.
There are the two ‘fairy mounds’ in the flats above the Black Bridge, conical gravel moraines created I think from debris carried down through the ice by a moulin – a stream running down and into the glacier. A similar but much larger complex of mounds can be seen almost blocking the glen just west of Luibeg Cottage, as well as more moraine ridges running down the eastern side of Coire Craobh an Oir.
Then there are the terminal moraines. How many people walking up the track to Derry Lodge are aware of walking through at least two of these? Blithely walking through what was once a bulldozed ridge of rubble at the nose of a glacier, but conscious only of two kinks in the road as it negotiates raised, sandy ridges. And how many sitting outside Bob Scott’s Bothy realise when they look across the river they’re looking at a cross section through another terminal moraine, and sitting where once a great snout of glacier would have been tumbling lumps of stone and ice on their heads?
All these traces and so many more of events so deep in the past, which have shaped the landscape – and the ecology – we see today, add to the richness of the picture we have of time and place in the Cairngorms. And though it all may have happened tens of thousands or even millions of years ago, there are always reminders that there is no switch between ‘then’ and ‘now’ in the mountains, but a continuum, with changes started deep in the past still in motion; barely discernible at times, yet sometimes sudden. Visit the deepest recesses of the Garbh Choire, where, with few exceptions, snows still lie year round and you see and feel ground still unstable, with shifting screes at the foot of cliffs and every year fresh scree added from the rocks above. Or walk the granite blockfields and pancaked outcrops of the MacDui plateau and see the progression of splits and laminations as the bedrock even yet is prised and forced apart by the freeze and thaw of water. Walk the glens and corries and see where modern floods have caused slope failures in what seemed stable hillsides, weaknesses built-in in the distant past suddenly revealed.
I stood once on snow, enveloped in cloud, in the innermost bowl of the remote Garbh Choire Mor and, effectively blind, listened as the spring thaw brought rocks clicking and cracking down the cliffs, noises echoing in a corrie that suddenly felt so claustrophobic, that was still, I realised, being hollowed out from the mass of the mountain.
It’s times like that which make you realise that, no matter how much geologists and geomorphologists talk of the distant past, the mountains are still making and telling their stories today – if only we could understand better what their signs are saying.