this survey (
in progress.. ) Sistema del Xitu
NB Passage name details are displayed in the status bar when the cursor is moved over
The original survey data was available for the main line as teletype or dot matrix printouts of input Distance, Bearing and Inclination data with calculated x,y,z coordinates from one of the Clarendon Lab's micros. Most of this, plus all of Cistra from 1983/4 were also available as a dataset prepared originally for a BBC micro. Some comparison of these with drawings revealed that they were in fact N, E, V values. Data was missing for the 1979 expedition Trench Series, Enterprise Series from 1980, most of Snowcastle, and Caracoles from 1983 and 1985. Also, the final bit of Traversety was represented by handwritten x,y,z coordinates. All the data was entered into Walls, together with dates and location so that appropriate magnetic corrections could be automatically applied. No instrument corrections were available, but the closure error on the large loop was minimal.
A node list was created and parsed into a spreadsheet (Lotus 1-2-3, but most would be just as capable) which was then used to create the list of Stations, thus:.
| Station { desc "ST" posn 0 0 0 } Station { desc "B1" posn 1.54 -1.28 -0.02 } Station { desc "B2" posn 2.7 -10.76 5.67 } Station { desc "B3" posn 13.03 -23.8 2.99 } .... |
A text editor (PFE) was then used to create the .wrl file. Each continuous section of passage to be shown with the same type of cross section was identified (easier said than done with old data: the symptom of not doing it is spurious connecting lines between unconnected surveys) and its stations included under a TubeSurvey node thus:
| Tube_survey { desc "Xitu Entrance" xsect [ 10 10, -10 10, 0 0, 10 -10 ] stations [ Station { desc "ST" posn 0 0 0 } Station { desc "B1" posn 1.54 -1.28 -0.02 } Station { desc "B2" posn 2.7 -10.76 5.67 scale 1 1 } Station { desc "B3" posn 13.03 -23.8 2.99 } ]} Tube_survey { desc "Entrance shafts" stations [ ........ |
< desc shows in status bar < defining coordinates, anticlockwise < scales subsequent xsect by width height < next tube/cross section of passage |
A header block was then added to specify predefined views, and the orientator
actually, it is also necessary to add a link station for every tube or else you end up with disconnected tubes
The cave is 1135m from lip of entrance to surface of sump pool. Total surveyed length is reported as* around 8km.
The exploration is described in Proc OUCC 9,10,12 and Beneath the Mountains. There was also a visit to William' Bit in 1993, but no survey was made despite some progress by a joint OUCC/MFC (Hungarian) group.
Since the main explorations, knowledge of the other caves of the area has advanced and it is now interesting to see how several distinct levels of development can be identified. Canalizos evidently bottoms at the same level as the Teresa Series, and the large chambers of Eton Palais and Hall of the Mountain Dwarf correspond with the London Underground in Oju la Bruja. The 2001 expedition revisited Cistra and pushed the upstream aven from Traversety into well decorated passage
Still remaining to be discovered:
The Canalizos shafts are also included on the survey, although there is no known link there is an interesting
concordance of cave levels. These were first explored by the SIE, and more extensively by OUCC in 1997.
* I could digress into the fractal nature of cave length as opposed to the absolute value
of depth, but will leave you to search out Earth Surface Processes and Landforms, Vol 12 No 5, pp475-480 (1987)
if you are interested.