Vertical caving terminology and methods > Ice and snow
A horseshoe-shaped trench dug into relatively firm snow, which a rope can be looped around, and used as an anchor. The bottom of the trench is angled inwards compared with the top, to make the rope stay in the trench. This might be useful to descend a snow cone into a cave entrance using a rope, where there is nothing else to use as an anchor. Softer snow needs the trench to have a larger radius, but if the trench is dug down into a softer layer of snow beneath a firm layer, the rope can cut through the softer layer, slicing off the snow bollard, and resulting in a fall. The strength of these anchors depends on snow conditions and how well they are made, but in general they are much weaker than standard anchors, but comparable to a good deadman, at around 400-500 kg in ideal conditions. With poor conditions or poor constuction, the strength can be exceeded by bouncing around on a rope. Snow bollards are best treated as a last resort only, with plenty of research into the best radius for different conditions. Their use requires the pull direction to be kept parallel to the snow surface, so each person using the rope will need to keep very close to the ground when near to the bollard.
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