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Report on the Cave Survey of Tham La-ong, Nan, Thailand

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Report on the cave survey of Tham La-ong, Khun Sathan National Park, Nan, Thailand
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Report on the
Cave Survey of Tham La-ong
Khun Sathan National Park, Na Noi, Nan

  
Martin Ellis
May 2019
Tham La-ong Cave Survey May 2019
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Contents
Summary ................................................................................................................................................. 2
Location ................................................................................................................................................... 2
Methods .................................................................................................................................................. 3
Results ..................................................................................................................................................... 6
Plan of Tham La-ong ............................................................................................................................... 7
Projected section of Tham La-ong .......................................................................................................... 8
Cave survey centre-line overlaid on Google Earth.................................................................................. 9
Description of the cave ......................................................................................................................... 10
Unsurveyed passages and leads ........................................................................................................... 15
Appendices ............................................................................................................................................ 16
Invitation to carry out cave survey .................................................................................................... 16
Permission to carry out cave survey .................................................................................................. 17
International Team Members ........................................................................................................... 18
Tham La-ong Cave Survey May 2019
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Summary
At the invitation of the Chief of the Khun Sathan National Park five international speleologists
performed a survey of Tham La-ong between the 5 and 8 May 2019. With the invaluable assistance of
National Park employees and a local guide, 2,969 m of cave passage was surveyed. This makes the
cave the 20th longest explored cave in Thailand. The survey is not complete with an estimated 200 m
of passage having been investigated without being surveyed and several pitches and side passages
not being explored.
Location
Tham La-ong is on the southern side of the Huai Pang Hat valley, 3 km south of Ban Chetawan in
amphoe Na Noi, changwat Nan.
Figure 1 Cave location map (with cave passage in red)
The UTM co-ordinates for the entrance (WGS 1984 datum) are 47Q 667270 2017316 and the
geographical co-ordinates are 18.2386°N 100.5820°E. The cave is at an an altitude of 620 m above sea
level.
Tham La-ong Cave Survey May 2019
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Methods
The location of the cave entrance was measured with a Garmin Etrex 20 GPS unit and cross-checked
on Google Earth. The expected accuracy is estimated to be +/- 15 m. The altitude is from the contour
lines in Google Maps.
The cave was surveyed using standard cave surveying techniques to the International Union of
Speleology survey standard of Grade 6-3-BEF.
Two DistoX2 cave survey units were used. These units are based on a Leica Disto A310 electronic
distance measuring device which have been modified with a custom built circuit board which allows
the Disto to also measure the magnetic bearing and the inclination. The DistoX2 units were calibrated
before use and cross-checked against a Suunto sighting compass.
Distances were measured with a precision of 0.01 m and the horizontal and vertical angles were
measured to a precision of 0.1°.
Figure 2 DistoX2 caving surveying instrument
In the cave the readings from the DistoX2 were recorded in a notebook and a sketch of the cave
passage was made.
Tham La-ong Cave Survey May 2019
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Figure 3 Example of cave survey field notes
All the survey stations were marked with a small dot of red or yellow nail polish. Some stations at
important junctions were also marked with the station number in white Tippex” correction fluid or
were flagged with orange tape. Where possible the survey stations which had been used by Alexander
Thoma in his 2016 survey where used in the 2019 survey. These are marked with pink nail polish.
After leaving the cave the data in the DistoX was downloaded via Bluetooth to an Android smartphone
running the Topodroid application. Topodroid allowed the progress of the survey to be seen on a daily
basis.
Figure 4 Topodroid data screen
Tham La-ong Cave Survey May 2019
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Figure 5 Topodroid survey screen
From Topodroid the survey data was exported to Walls, a cave surveying program. With Walls the
cave survey data was organised and managed, the closed traverses were closed and adjusted and the
survey was formatted to a size equivalent to the size of A2 paper (84 cm x 59 cm).
Figure 6 Walls cave survey program
From Walls a SVG format file with the survey centre-line and passage outlines was exported to Adobe
Illustrator and the final surveys were drawn.
Tham La-ong Cave Survey May 2019
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Results
Using the techniques described above an International Union of Speleology survey grade of 6-3-BEF
was achieved.
6 - calibrated DistoX2 type survey
3 - passage details are from sketches made in the cave
B – survey loops are closed and adjusted
E survey data has not been transcribed manually, but was transferred electronically from the
DistoX2 to the survey program
F the cave entrance location has been precisely measured using GPS
A total of 2,769 m of centre-line was surveyed, and in addition the drawn survey shows a further 170
m of unsurveyed oxbows and a 30 m unsurveyed inlet. This gives a total length of 2,969 m. The cave
has a vertical range of 49 m.
There were five survey loops:-
Loop
Survey stations
Loop length (m)
Misclosure (m)
A
26-27-28-29-30-31-32-33-34-35-
36-37-38-39-40-41-42-43-44-45-
46-47-48-49-50-51-52-53-54-55-
56-57-58-59-60-61-62-26
389.4
5.0
B
23-24-25-251-252-253-254-255-
256-257-258-259-260-261-262-
209-208-207-206-205-204-203-
202-201-23
351.9
5.1
C
25-26-27-28-29-30-411-412-413-
414-415-416-417-261-260-259-
258-257-256-255-254-253-252-
251-25
274.6
1.2
D
262-263-264-265-266-267-268-
269-418-419-420-421-422-423-
424-425-426-427-428-429-430-
431-432-436-437-438-439-440-
441-442-443-444-262a-262
460.9
7.0
E
303-302-301-48-319-320-321-322-
303
64.5
2.4
The Walls survey files and scans of the survey notes have been archived on the Cave Registry Data
Archive maintained by the British Caving Association:
The survey files, NA0067A.SRV, NA0067B.SRV, NA0067C.SRV and NA0067D.SRV, are located at
http://www.cave-registry.org.uk/svn/Thailand/Nan/.
The scanned survey notes files NA0067A Tham La-ong - May 2019.pdf, NA0067B Tham La-ong - May
2019.pdf, NA0067C Tham La-ong - May 2019.pdf and NA0067D Tham La-ong - May 2019.pdf are
located at http://www.cave-registry.org.uk/svn/Thailand/zSurvey%20Field%20Notes/Nan/
Tham La-ong Cave Survey May 2019
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Plan of Tham La-ong
Tham La-ong Cave Survey May 2019
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Projected section of Tham La-ong
Tham La-ong Cave Survey May 2019
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Cave survey centre-line overlaid on Google Earth
Tham La-ong Cave Survey May 2019
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Description of the cave
From the entrance a horizontal passage, 3 to 5 m wide by 2 to 4 m high, leads for 75 m to a flat out
crawl which is 2 m long. Once through the crawl the passage starts to get larger and by Stn (Survey
Station) 17 it is 8 m wide and 10 m high. The passage continues like this for 75 m, with a couple of
climbs down and back up, to Stn 23. At the lowest point along this passage there is a series of low
oxbows that bypass the climbs and at the northern end of the oxbows, below Stn 17, there is an
unsurveyed link via an exposed traverse to Stn 49.
Photograph 1 Large passage between Stn 17 and Stn 23 (T. Bolger)
At Stn 23 a climb up to the right leads to a passage, 5 to 8 m wide and 3 to 5 m high, which after a
section where the floor is covered with small, old gours ends after 150 m at a 10 m pitch (Stn 209).
Back at Stn 23 heading down the slope to the left leads through a small chamber to Stn 25. From Stn
25 passing over the top of the 10 m climb down leads to a chamber with Stn 252.
From Stn 252 there are two ways on. To the left, at the lowest point in the chamber, there is a well
decorated passage, 1.5 to 2 m high and 5 to 10 m wide, that heads south for 100 m to an undescended
8 m pitch (Stn 410). 20 m along this passage there is another undescended pitch on the right near Stn
403.
The other way on from Stn 252 is up and to the right where a 100 m long passage, floored with
extensive ‘lek lai’ manganese oxide deposits, reaches a 4 m climb down a boulder slope that has a
distinctive 1 m deep trench amongst the rocks. At the bottom of the climb there is a passage on the
right that heads towards Stn 30 (described below) while to the left the passage soon opens up into a
large chamber with Stn 262.
Tham La-ong Cave Survey May 2019
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The 10 m pitch from Stn 209 comes into this chamber on the right. At the base of the chamber, to the
left, there is an awkward 2 m climb up into a chamber and then a passage that leads to the large rubble
chambers. The easiest way on from Stn 262 is up the slope and a 2 m climb on the right to a wide
passage floored with manganese oxide deposits. After 50 m this passage ends at a 4 m climb down to
the “Little Elephant” rock formation.
Photograph 2 “Little Elephant” rock formation (P. Dummer)
The passage heading north from the “Little Elephant” has not been investigated. Heading south from
the “Little Elephant” one soon reaches another 4 m climb down into a large passage. At the base of
this climb the passage heading north has a 3 m climb down after a few metres which has not been
descended. Going right (south) from the base of the 4 m climb there is a passage up to the right at Stn
269 that leads to the rubble chambers (described below).
Continuing along from Stn 269 the passage soon reduces in size before making a sharp turn to the
right (north). After 50 m the passage follows a hading rift formed along a fault for 20 m before the
passage turns left and away from the fault. The passage then trends south for 120 m to end at Stn 286
where there is a 19 m pitch down to the seasonal streamway.
Back at Stn 269 a small passage to the north ascends steeply up a slope of rocks and rubble and soon
opens up into the largest chamber is the cave. This chamber is probably formed on a fault and has
scree slopes formed from angular rubble with some larger rocks and boulders. The chamber is also
quite well decorated with speleothems and there is some bat guano. The route through the chamber
is to stay high up and follow the top of the rubble slopes while heading south-west to Stn 424. From
here one descends to the east and at the lowest point in the chamber there is a route through the
boulder choke to a passage with Stn 432.
Tham La-ong Cave Survey May 2019
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Photograph 3 Formations in the large rubble chambers (S. Subramanhya)
At Stn 432 the passage heading south soon ends. The way on is a comfortably sized passage that heads
north-east to a mud-floored chamber. At the far end of this chamber is the top of the awkward 2 m
climb down to the Stn 262 chamber.
From Stn 25 there is a 10 m climb down to Stn 26 which is in a 2 to 4 m wide and 5 to 8 m high
horizontal passage. Going south-west from Stn 26 there is 50 m of passage before reaching Stn 30,
which is at the top of an 8 m climb down to the seasonal streamway. By not descending the climb and
continuing past Stn 30 the passage heads south and is well decorated including cave pearls and a set
of large, dry gours (these are the “ong” that give the cave its name). The passage leads to the base of
the 4 m climb with the trench and ends at the chamber with Stn 262.
Back at Stn 26 going north leads through a small chamber before reaching a couple of boulder chokes
that are easily passed. The passage then opens up again into a 2 m wide by 8 to 12 m wide mud-
floored passage and after 50 m of easy going there is a fine, white, sparkling flowstone bank on the
northern wall (Stn 52). Just past this flowstone there is a 7 m hole in the floor down to the streamway
and then one reaches Stn 49.
From Stn 49 there is an unsurveyed link to Stn 17 that is estimated to be around 200 m long. This link
has an exposed traverse that would be safer if it was roped. The other way on from Stn 49 is down a
7 m climb to the streamway. The top 2 m of this climb is difficult and a rope is recommended for
descending the climb.
Tham La-ong Cave Survey May 2019
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Photograph 4 Surveying in the passage between Stn 26 and Stn 30 (T. Bolger)
The climb down from Stn 49 reaches the seasonally active streamway at Stn 48. Going downstream
(north) there is a junction after 60 m at Stn 306. On the right there is a short climb up into a passage
at a slightly higher level that ends at a boulder choke after 60 m (Stn 318). Continuing downstream at
Stn 306 in the main streamway also ends at a boulder choke after 75 m (Stn 312). Both these
downstream boulder chokes are close to the surface.
Photograph 5 Sandstone dyke in the seasonal streamway near Stn 103 (T. Bolger)
Tham La-ong Cave Survey May 2019
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Heading upstream (south) from Stn 48 there is 175 m of large, and in places well decorated, passage
before reaching Stn 34 which as at the bottom of the 8 m climb down from Stn 30. Continuing
upstream from Stn 34 one soon reaches a 1.5 m high sandstone dyke, which can also be seen in the
ceiling. After the sandstone dyke the passage opens up into a chamber at Stn 103. From this chamber
there is a low, unsurveyed oxbow that heads downsteam to rejoin the main passage beyond Stn 34.
From Stn 103 the seasonally active stream passage continues in a south-easterly direction for 175 m
to Stn 118 where there is an unsurveyed, 30 m long, inlet passage with gours entering on the right.
After Stn 118 the passage reduces in height and has a couple of crawling sections before opening up
after 75 m at Stn 125 which is at the bottom of the 19 m pitch from Stn 286. From Stn 125 the passage
mainly has a high roof for the next 200 m to an unexplored inlet on the right at Stn 138.
Beyond Stn 138 the passage becomes a low, muddy crawl for 50 m before the roof rises again to
walking height. The upstream passage ends after 100 m in a boulder chamber with a boulder choke at
Stn 154. There is a small, draughting hole at the top of the choke, but this has not been pushed as
there are signs that this point is close to the surface.
Photograph 6 Spiral stalactite in seasonal streamway near Stn 48 (T. Bolger)
Tham La-ong Cave Survey May 2019
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Unsurveyed passages and leads
(1) There is a link from Stn 17 to Stn 49 that is a couple of hundred metres long. It includes an
exposed traverse that would be safer if it was roped.
(2) There is a series of low oxbows in the entrance series between Stn 17 and Stn 23.
(3) The passage heading northwards from Stn 266, the Little Elephant, has not been
investigated.
(4) Exploration of the passage heading northwards from Stn 267 stopped at the top of a 3 m
climb down.
(5) There is an undescended 8 m pitch at Stn 410, which might link with leads (3) and (4).
(6) There is an undescended pitch at Stn 403.
(7) A passage heading north between Stn 29 and Stn 30 has not been investigated.
(8) There is an unexplored ascending passage at Stn 279.
(9) The holes in floor at Stn 275 and Stn 278 have not been investigated.
(10) The steeply inclined rift on the climb between Stn 30 and Stn 34 continues southwards at Stn
32.
(11) A passage in the left hand wall in the streamway between Stn 48 and Stn 301 has not been
investigated.
(12) There is an unexplored inlet in the streamway at Stn 113.
(13) There is a small unexplored inlet in the streamway at Stn 138.
(14) The small passage in the streamway at St 149 has not been pushed.
(15) There is a small lead, with air drafting out, at the top of the boulder choke at the southern
end of the streamway (Stn 154).
Tham La-ong Cave Survey May 2019
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Appendices
Invitation to carry out cave survey
Tham La-ong Cave Survey May 2019
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Permission to carry out cave survey
Tham La-ong Cave Survey May 2019
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International Team Members
Dr Terry Bolger (USA)
Mr Paul Dummer (UK)
Mr Martin Ellis (UK)
Mr Robert Harper (UK)
Mr Sudeep Subrahmanya (India)
Photograph 7 The 2019 survey team (T. Bolger)
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