Duncan McCallum: 'Bouldering is about what you physically can and cannot do'

For an instant, in that moment of impact, the world stood still as Subaru and hunter's target collided. One bred to provide the tweed-clad with a kill trophy, the other built to transport with road-sucking handling. Thousands of well-bred birds lined the A68, oblivious to the dangers of flying into the path of metal machines and getting in the way of the small bands of late autumn, cold rock hunters.

Northumberland is a very special place, tens of sandstone edges break though the moorland heather all over God's county, providing some of the best bouldering (climbing without ropes) in the UK. After a caf stop to indulge in fruit scones, cream and jam, washed down with strong coffees, the four of us piled back into the car and headed to "Back Bowden" crag. After a short walk across the moor, we arrived at the sunlit cliff.

And so the ritual begins, a slow warm-up, both mentally and physically. It's time to loosen the drive from the neurons and engage in a world of ice-cold rock, power and friction. The finger tendons are supported by rolls of zinc medical tape and climbing shoes are squeaked and rubbed clean. The rock is cold and bites into the skin, the pressure and the cold squeezing the blood from the fingertips. After a minute or so the hot aches begin, painful but welcome. They herald the start of the day's full action.

Bouldering is about learning what you physically can and cannot do. It's about pulling on the smallest holds you can imagine; attempting the hardest movements you will ever do without the encumbrance of rope and gear. It is the essence of climbing - pure movement. It's raw because it comes down to skills and strength, nothing else. I think that is why it's such a fabulous volume in the mountaineering library. Unlike tramping up an Alpine peak, which is a macro experience in so much as it involves thousands upon thousands of individual movements made over great distances, a bouldering problem may only have five or ten body movements made on a three to six metre high lump of rock in a field full of sheep. It's a chance to get involved in a world of micro subtleties. It's the millimetre-perfect placement of a foot. It is the ability to use a minuscule hand hold where the ancient grains of embedded sand have to be caressed, or crushed into success. It's about trying and not being put off by failure. Ultimately, though, it's not the climbing I regard with most fondness. It's the crunch of the frozen grass underfoot. The sharing of the coffee flask, the encouraging others to push to their limits and being pushed myself to attain what at first may have seemed out of reach.

• This article was first published in the Scotland on Sunday on November 7, 2010