What is the best technique for self-arrest on a sandy slope? I was canyoneering last week and the sand in the canyon was very soft and powdery--with a steep drop off at the bottom of the slope. Luckily I did not have any issues, but I was trying to figure out the best technique for self-arrest on a sandy slope--similar to self-arrest with an ice axe on a snowy slope. Any suggestions? I thought that plunging a longer backpacking knife, like a 7 inch blade, into the sand with your body weight over it might work--but this is just an idea.
You can use a snow self arrest technique (one that you use if you don't have an axe). Basically you want to dig your hands and feet into the "surface" as much as possible, thus concentrating your body weight into as small an area as possible:
A walking stick might help, but I think your best bet is going to be to sprawl out flat and dig your hands as deep into the sand as possible.
Sand is not like ice. You can self arrest on ice because it's a medium that you can create friction on (scratching your pick into the ice), but sand isn't solid, it moves; flows. Getting caught in a sluff of sand would be a lot like getting caught in a stuff of snow, or an avalanche. Your only chance of not going down with it is to dig deep and try to find something to anchor onto. Your knife may work, but only if you have it out while you're walking, so it's in your hand the moment you slip. I wouldn't recommend this however, because there's a chance you could fall onto your blade.