The full moon is out tonight and the sky was clear, so I decided to make use of it. A rapid ascent of the Coire nam Beithach path brought me into the coire beneath the cliffs of Bidean and Stob Coire nam Beith. I hadn't even had to switch on my headtorch: the moon was so bright it couldn't be looked at directly, and colours were bright and easily distinguishable.
From my perch on a boulder, I contemplated the giants surrounding me on all sides. The mountains look much bigger, steeper, and more forbidding by moonlight. My objective, the Central Gully of Bidean, was a grim slot in the huge northern cliffs. After checking the snow (it was absolutely solid and safe neve), I began climbing up to the start of the route.
There are four potential entrances to Central Gully, and I checked them all. The leftmost one was too thin for me to be doing without a rope in the middle of the night, so I let it be. Two more featured very steep mixed steps that I would have preferred a rope for, and the only remaining one was a 5m step of near-vertical ice. I started up this steep step. The ice itself was as hard as diamond and extremely brittle, no doubt due to the fact that the temperature was about -10! Most of the time my picks were actually bouncing off the surface, but when I did get a stick, it dinnerplated horribly.
I admitted defeat, and considered heading round to do North Route. However, on the traverse across the snowfield, I suddenly heard a loud 'bang' and a shooting crack appeared at my feet. I froze and got my axe ready, should the worst occur. An instant later, a very large section of hard windslab sank about 6 inches down the slope, overbalancing me. I managed to arrest the slip before it became a fall, but I took it as a warning and got out of there as fast as I reasonably could.
The only explanation for this that I can give is that there must be highly isolated and almost random pockets of slab masquerading as regular neve. I was quite happy that most of the snow I was climbing on was entirely safe, having dug several test pits on slopes of the same aspect and altitude, but it goes to show that you can never be entirely certain. I was very lucky.
A lovely walk in the moonlight though!