3938: cave (Builder's Bum Hole)
Trillos 30T 447808 4793938 (Datum: ETRS89. Accuracy code: G) Altitude 633m
Length 66m Depth 15m
Area position

Updated 5th December 2014; 6th May 2016

   A rift slopes down at 40° some 30m on a joint. A too small hole at the bottom has no draught.  Ten metres in, below a 3m climb, is a passage on the right (looking out) that drops into a small boulder chamber and dig. This chamber connects to site 3939. There is a good draught in on a warm but windy day, so needs checking on a still, hot day. The total length of the combined system is some 45m.
Other GPS readings are 30T 0447901 4794147; ETRS89: 30T 447799 4793938 and 30T 0447936 4794122; ETRS89: 30T 447834 4793913.
   In October 2014, the dig at the bottom of the entrance rift was excavated to squeeze-size which then reached a small choked slot which is not worth digging. The best option is now the choke in the chamber between the two caves, marked as "dig" on the survey. Some work was carried out here under a hading roof at Easter 2016.

Reference: anon., 2013e (autumn logbook); anon., 2014d (autumn logbook); anon., 2016b (Easter logbook)
Entrance picture : yes
Underground pictures : yes
Video :
Detailed survey : pdf
Line Survey :
On area survey :
Survex file : yes