In order to explore uncharted, terrestrial, depths - one needs the proper equipment, training, and terminology to communicate with other members of the expedition. One may find the following information useful:
CALL. n. A specific verbal signal (usually yelled) by a caver to another, to indicate an action, intended action or possible danger.
ABSEIL. v. The act of lowering oneself down a cliff, pitch or steep slope on a fixed rope. The controlled descent is obtained by friction of rope on the body or passing the rope though a karabiner or other descending device. Derived from the German word ‘abseilen’.
DESCENDER. n. A mechanical device used for controlled descent of a pitch or steep slope. It works on the principle of applying friction on a fixed rope to obtain controlled descent for the abseiler.
ASCENDER. n. A mechanical device which grips the rope (usually with a cam operation) and allows a person to ascend a rope.
AVEN. n. A shaft which rises from a passage, sometimes leading to a passage above, but not open to the surface.