Hourglass (rock formation)

Hourglass on the pen-field rock near Dahn

An hourglass is a - mostly smaller - characteristic expression in the rock of mountains or cliffs. The hourglass is an arched cavity in the rock that encloses a rock spigot. Hourglasses are typically found in limestone and sandstone rocks. The name is derived from the similarity of the rock plug with the shape of an hourglass .

When climbing , hourglasses are used as natural fixed points by placing a sling around the hourglass. When the opening is large enough, you double the loop, as shown in the picture. Care must be taken not to fix the sling with an anchor hitch, otherwise it will tend to tighten further up towards the thinnest - i.e. weakest - point. In the case of a small opening, the fuse is simply threaded, whereby it is best to use a stiff cord that is knotted with a pocket stitch .

In climbing guides , all structures that offer a fixed point through an undercut in the rock are now marked with SU for hourglass, even if they do not have the typical hourglass shape. From time to time this also applies to fixed points, which can be set up in the same way on terminal blocks.

The safety principle of the hourglass is also used in the ice hourglass as a self-made fixed point safety option with loop formation.

Individual proof

1. ↑ Olaf Perwitzschky: Climbing , BLV-Verlag, Munich 2007, ISBN 978-3-8354-0238-6 , page 102