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The biggest problem in climbing jam cracks is the pain. As a simple machine, the wedge is an excellent force amplifier. You can split a log with a wedge and a sledge hammer because the shape of the wedge amplifies the downward blow of the hammer and directs it outward. When a climber uses a hand as a wedge to support his weight, a force much greater than his weight is transmitted through the hand to the rock. The hand wedge tries to split the crack apart. This force is applied directly through the skin to the rock of the crack. Usually, the crack does not split open. The rock pushes back on the skin with a force that is large enough to be painful, and which may even cut the skin if there are any sharp crystals in the crack. I was glad Mike was leading now, since he had wrapped his hands in adhesive tape to protect his skin from abrasion. |
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Skin is amazing. The folds in the skin on the back of a knuckle allow the
skin to unfold to 1.8 times its original length before it begins to stretch.
It can then stretch elastically to more than double its original length
before it breaks. When the hand is first jammed into a crack, like the one
Mike was climbing, the skin will stretch and move, which can cause the hand
to slip from the crack. Tape on a hand does not stretch. It anchors the
skin in place, making the climbing of jam cracks more secure. (The tape
plays another important role as well. It connects the fingers to the wrist
and acts like an external ligament, transmitting some of the force from
the fingers to the wrist bones and easing the work of the internal ligaments
and muscles.)
As Mike moved higher, the crack narrowed down until his fist wouldn't fit, so he switched to finger jams. Mike piled his fingers, one on top of the other, inside the crack, keeping his elbow pointing straight down. When he raised his elbow, his fingers were twisted hard into the sides of the crack where they stuck solidly by friction. Occasionally, he would stop and hang from one finger jam to place protection with the other hand. Before long, he had climbed fifteen stories above me, and it was my turn to follow. |
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Following is fun. The rope runs straight up to Mike who takes up the slack as I climb. Without worry, I could enjoy the pleasures of strong, precise, balanced movement. A climbing school in Colorado has captured the spirit of climbing perfectly in its name, "Dance in a Vertical World." I even whistled a bit as I climbed. Whenever I reached one of Mike's pieces of protection, I paused and removed it. We left nothing behind. I joined Mike at the ledge just as the sun peeked over the top of the cliff, bathing us in warm light. I was having fun and was happy to take the lead again. |
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