A group of five cavers descended the 100 foot pit of the Rubber Chicken Entrance of the Friar's Hole System in West Virginia at around 5 p.m. on November 13. They explored until 11 p.m. At that time the outside temperature was about 10 degrees with surface air blowing down the pit. It was estimated to be about 30 degrees at the bottom. The cold air and a waterfall in the pit caused icing of the rope. Two ascended on Gibbs systems and encountered no problems except minor frostbite due to wet gloves. The others were on Jumars which slipped on the icy rope. One made it out by repeatedly warming the Jumars in his mouth. Eventually Gibbs systems were relayed down to the stranded pair. The cold caused almost all to suffer some degree of frostbite and hypothermia.
NSS News, May 1981(Part 2) V39N5, Page A17
Doug Jacoby "Trip Report" Subterranean Sun 6:12 Dec. 1976
A fine example of a deficiency of the Jumar or other toothed, spring-loaded ascender versus a cam-gripping ascender. On a very muddy or iced ropes, a Jumar will become clogged and slip.