Belfry Bulletin

Search Our Site

Article Index

 

Tai Rom Yen 1998

Editor – Rob Harper, BVM&S, MRCVS, FRGS.

INTRODUCTION

This is an account of a short reconnaissance trip made during January of 1998 to assess the speleological potential of the Tai Rom Yen National Park in Surat Thani Province in Southern Thailand.  It was a joint project involving both Thai and British cavers as well as employees of the Royal Forestry Department of Thailand.

The Tai Rom Yen National Park is situated near Surat Thani approximately 640km south of Bangkok on the eastern side of the peninsula.

EXPEDITION MEMBERS

Tony Boycott - (UK)                          Bristol Exploration Club

Rob Harper - (UK)                             Bristol Exploration Club

Dean Smart - (Thailand)                    Royal Forestry Dept.

Anukoon Sorn-Ek - (Thailand)            Royal Forestry Dept.

ACKNOWLEDGEMENTS

We are very grateful for all the help and generous hospitality received from the employees of the Royal Forestry Department in the Tai Rom Yen National Park.

In particular ....

Chief ..................................................................... Sunlit Sirichot

Assistant Chief ...................................................... Somsak Suphanpradit

Head of Phetphanomwat Ranger Station .................. Racheng Ranthaphun

Head of Khong Ngai Ranger Station ......................... Nara Kongkhiaw

Rangers ................................................................ Saming Musikawong

............................................................................. Banjong Niyarat

............................................................................. Jetsada Maneechai

............................................................................. Jarin Meunsawat

............................................................................. Saengthawee Hanprachum

............................................................................. Somcheua Romkhiri

............................................................................. Somyot Saejeu

............................................................................. Somdet Saejeu

............................................................................. Liem Kaeonark

............................................................................. Chorb Chaidet

............................................................................. Prayut Lorbthong

............................................................................. Chaliew Klingklaow

............................................................................. Sithichoke Heetket

GEOLOGY

The karst and caves of Thai Rom Yen National Park are all formed in limestones of Permian age (c.275-235ma) called the Ratburi Group.  This limestone is found throughout Thailand, except for the north east. It is hard, massively bedded and light to dark grey in colour.  At Tai Rom Yen, metamorphic processes have altered the rock to marble and many, white calcite-filled fractures criss-cross through it.

During the Permian period, Thailand was positioned upside down on the equator.  Tectonic activity was quiet and a stable platform developed in a warm, shallow sea - an ideal habitat for shelled marine creatures. The shells of these animals accumulated up to 2,000m thickness. Fossils of the Ratburi group include brachiopods, corals, gastropods and fusilinids.

Later, during the Triassic period (c.225-190ma) Thailand drifted northwards, span around 180 degrees and collided with Indo-China.  Marine sandstones and shales were deposited on top of the limestone as the sea became deeper.  Granite plutons pushed upwards through the Earth's crust.  Heat from the granites turned the limestone into marble and the increased pressure fractured it severely, forming the calcite veins.

Further tectonic movements in the Cretaceous period (c.135-65ma) faulted and uplifted the rocks into mountains.  Erosion began and the karst landscape we see today started forming.

Finally, in the last 2 million years, rivers eroded sediments from the mountains and deposited them as the flat plains surrounding the area.  Relative sea level changes of up to 300m in amplitude have also helped to shape the local scenery.

Karst in Tai Rom Yen National Park presents a variety of forms.  There are isolated remnants of limestone on top of a granite base, as seen near the headquarters.  Caves here are short, inactive parts of much older, longer systems which carried underground streams.  Erosion of the limestone broke up the old caves and diverted the streams onto the surface.  Tham Ngu is a good example.  A single active cave, Tham Nam Lod, is small and probably young in age.

More extensive areas of karst in the northern part of the park contain longer underground cave systems up to 4km in length.  Here, dolines capture rainwater falling on the limestone and streams flowing off the granite and sandstone sink at the edge of the karst.  The water emerges again at caves such as Tham Khlong Wat, Tham Huai Khang Khao and Tham Huai Sit.  These caves are quite small in size and their passage shapes suggest that they are also young in age (especially Tham Huai Sit).  Large, inactive, upper level caves do exist as at Tham Men. These caves are much older.

Khao Nan Daeng is an example of a karst ridge, aligned with the general geological structure of the area (N-S).  Bedding planes in the limestone are near vertical and also aligned N-S, but the ridge probably formed by fault movement on either side.  Caves here include ancient, inactive caves, such as Tham Men, and younger, active caves carrying a stream through the ridge, e.g. Tham PIa.

All of the caves in Tai Rom Yen have an origin in the phreatic zone (beneath the water table). Round chambers and smooth walls (Tham Men and Tham Men) are evidence of this.  The younger, still active caves are developing partly in the phreatic zone when rainy season floods fill the caves to the roof (round to oval passage cross sections in Tham PIa, Tham Khlong Wat, etc.) and partly in the vadose zone (above the water table) during the dry season.  Tham Kraduk is also originally phreatic.  Here though, the cave has a very flat roof due to near static water from the surrounding marsh entering the cave and evenly dissolving away the roof.

GEOGRAPHICAL LOCATIONS

 

 

CAVES

The caves examined were in four areas.

1. Khao Nan Daeng

This sharp limestone ridge starts approximately 1 km North-East of the town of Amphoe Ban Na San and runs approximately North for about 5 km rising to a height of 300m and varying in width from 0.2 to 0.5 km.   Although many cave entrances are visible, only three systems were visited on this trip.

Tham Men ("Smelly Cave")

LOCATION

The Buddhist temple beside the lower entrance to this cave is easily seen from the main road from Amphoe Ban Na San to Ban Khlong Ha.  Drive towards the temple and then follow the road beside this temple to the North until a signpost on the right hand side with a picture of the cave.  From here, an obvious path leads up the hillside to the main entrance.

DESCRIPTION

From the large entrance chamber two passages lead on.

To the right, a complex maze of small phreatic passages eventually leads to single low passage heading to a lower entrance directly above the temple.

Straight ahead, a low stoop leads to a rift approximately 10m deep, (fixed ladder in situ).  At the bottom left leads to a small series of rift passages which were not pushed to a conclusion while right leads to a series of large dry fossil passages with good formations.

At one point, a series of pitches can be seen descending to a possible lower level but these were not descended owing to lack of tackle.

This cave was not surveyed owing to a lack of time.  A Grade 1/2 survey done by local cavers would indicate approximately 2km of known passage.

Tham Kraduk ("Bone Cave")

LOCATION

From Tham Men follow the road North paralleling the western side of the ridge for approximately 3kms then turn right along tracks heading towards the base of the cliff.  At the narrowest point of the ridge below a col is a stream resurging from a cave (Tham Pla) Tham Kraduk is found at the base of the cliff approximately 300m to the South. Local guidance is extremely useful.

DESCRIPTION

Depressing series of low phreatic mud floored passages and occasional crossrifts.

From the entrance crawl a passage to the right 2 to 4m wide and approximately 1m high parallels the cliff face and daylight can be seen through a small hole on the right hand side.  This passage ends in a wide chamber.  About 10m from the start of this passage, another passage on the left-hand side can be followed past several cross rifts to a small sump in a rift in the floor. The passage to the right of the sump closes down within a short distance

 

Tham PIa ("Fish Cave")

LOCATION

See Tham Kraduk

DESCRIPTION

Follow the stream to its resurgence, underneath a huge boulder, at the base of the cliff.  Climbing over this boulder allows access to a rift dropping into waist-deep water.  A stooping sized passage quickly leads to a short gravel floored crawl and after approx.  10m this opens out into a large river passage.  This can be followed upstream.  Passage dimensions vary between l0x6m to 5x5m with occasional low stoops and a short section of swimming at a duck to end in a large boulder ruckle.  Several small passages and low ducks allow penetration of this ruckle but no way through could be found.  There may be a passage over the top but this could not be reached.  According to local people, this boulder ruckle is only just inside the entrance of the stream sink on the opposite side of the ridge.

Several parallel/oxbow passages were noted.

2. Near Tai Rom Yen National Park Headquarters.

Tham Ngu ("Snake Cave")

LOCATION

At the "T" junction at the end of the road from the Park Headquarters turn right and stop at a rubber plantation on the right after approx. 3km. The cave is located high on the hill behind this plantation.  Follow the path from the plantation across the stream and follow a poorly defined gully. Local guidance is essential.

DESCRIPTION

A large and very well decorated entrance chamber leads to two short walking passages either side of a pillar.  These quickly unite shortly before the cave ends at a series of dry gours home to a sizeable snake.



Bamboo Rat in Tham Nam Lod – Photo: Tony Boycott


Cave Racer snake in Tham Ngu – Photo: Tony Boucott

 

Tham Nam Lod ("Stream Cave")

LOCATION

In the slopes directly opposite the Park Headquarters.  From the road drop down into the valley and cross the stream to an old abandoned banana plantation.  From here, follow the small stream up to the cave from which it resurges. Local guidance is extremely useful.

DESCRIPTION

From the entrance a single stooping height gravel floored passage ends after about 30m at a small sump.  A small phreatic tube to the left of the sump rapidly becomes too tight and is home for a bamboo rat!


3. Near Phetphanomwat Field Station.

Tham Khlone: Wat ("Temple Stream Cave'')

LOCATION

From the field station, follow the obvious path on the opposite side of the road down into the valley meeting the stream at a small Buddhist shrine. Although the cave can be entered via the resurgence of this stream, it is simpler to follow the small cliff around to the left for approximately 30 to 40m to an obvious flood resurgence.

DESCRIPTION

The walking sized passage is followed until the main stream passage is encountered.  From here the stream can be followed along a winding passage via a series of pools some of which require swimming to a stal blockage with the stream emerging.

A short crawl and two ducks under the stal blockage lead to a short cascade and then a deep sump.

Above the stal blockage, a rift passage can be followed to a second stal blockage probably at the same level as the sump.

On the left hand side of the passage about 20m towards the entrance from the stal blockage is a short inlet passage.

There are several inlet and outlet passages near the entrance.


Tham Huai Khang Khao ("Bat Cave")

LOCATION

This cave is located in the hill behind the field station.  From the field station head slightly right up the hill and follow a shallow streambed, and a black water pipe, to the entrance of this resurgence cave.

DESCRIPTION

A large passage with silt banks leads to a gloomy stream passage with many bats.  Walking and wading eventually leads to a sump after approximately 170m.

Near the entrance, there are several outlet passages some of which lead to alternative entrances. In one passage a fossilised elephant tooth was found.

The only inlet passage on the right hand side about 35m downstream from the sump rapidly ends in a loose boulder choke.


 

Fossil Elephant molar in Tham Huai Khang Khao – Photo: Tony Boycott


Frig in Tham Huai Khang Khao – Photo: Tony Boycott     

4. Huai Sit

Tham Huai Sit 1& 2 ("Sit's Stream Cave 1 & 2")

LOCATION

From the village, follow the obvious river upstream to its resurgence from underneath a pile of boulders.  The entrance to Huai Sit 1 is an intermittently active stream passage in a 3m deep cleft approximately 30m along the base of the hill to the right. Huai Sit 2 is the obvious 2mdiameter passage heading into the hill about 10m further round and about 10m higher up the hill.

DESCRIPTION

Huai Sit 1

A narrow hading rift passage is followed to a cross-rift which debouches into the large main stream passage.

Upstream the passage enlarges at a boulder pile with the stream emerging from a sump immediately beyond.  A sand-choked rift above the sump emits an impressive draught.  Downstream swimming around a comer leads to a further 30m of swimming to another sump, which must be very close to the surface.


Huai Sit 2

The impressive passage rapidly deteriorates into loose tight muddy rifts with bad air to a sump. The side passages revealed nothing of significance.


Tham Men (“Porcupine Cave”)


Rob Harper in entrance to Tham men (Huai Sit) – Photo – Tony Boycott


Gecko on curtain in Tham men (Huai Sit) – Photo – Tony Boycott

LOCATION

From either Huai Sit 1 or 2 head directly upslope for about 40 to 50m. The cave is located in an indistinct gully at the base of a small cliff.  This is not easy to find - even the locals did not know that it was there!

DESCRIPTION

The entrance squeeze leads down slope over hard packed silt passing over a blind shaft in the floor (bad air) and enlarges to approx. 10x10m at a chamber. Much evidence of porcupines throughout the cave.

From this chamber, a walking passage can be followed to a stal obstruction. A low crawl on the right leads to a short hands and knees crawl to a static sump.  This passage contains many dusty formations including gour pools and false floors as well as evidence of intermittent flooding.

The only significant side passage leads from the true right hand side of the large chamber near the entrance.  A rising passage leads for 40m through a series of small chambers to a point that must be very close to the surface.

5. Other unvisited caves in the area:

Unnamed Cave

LOCATION

Southern end of Khao Nam Daeng

DESCRIPTION

Flooded in all but the dry season when a very muddy, wet passage can be followed for several hundred metres.

Tham Mek

LOCATION

In cliff face above and behind the park headquarters.

DESCRIPTION

Rock shelter containing gour pools and bees' nests.

Tham Khi Khang Khao

LOCATION

1 hrs walk E of Phetphanomwat Ranger Station.

DESCRIPTION

Small dry cave used by locals for extraction of guano.

Tham Nam Sap

LOCATION

1hrs walk N of Tham Khi Khang Khao

DESCRIPTION

Probably a stream sink cave.  No further details.

Tham Nam Lod

LOCATION

To the E of Phetphanomwat Ranger Station the Nai Chong, Wat and Kong Chang streams join and sink into a cave at about G.R. 584 874.

DESCRIPTION

A large stream sink which is possibly choked with logs.  No further details.

FAUNA

The caves explored contained a large population of animals.  The high-energy tropical environment of most caves with frequent floods and multiple entrance systems favours large populations, mostly of troglophiles and trogloxenes, but some true troglobites were seen.  Many bats were seen, of at least two different species, but surprisingly no fruit bats were seen.

As a small reconnaissance expedition, we were not intending to collect any biological specimens.  The elephant molar found in Tham Khang Khao has not yet been specifically identified.  However, a bat skeleton found in Tham Men ("Smelly Cave") has been identified.  It could be one of four similar species, but we are most confident that it is a Hipposideros lekaguli.  This is quite a rare species of bat that is native to Thailand and this population would probably merit further evaluation.

Fauna List

(Species without cave name in brackets were seen in most caves visited.)

MAMMALS

Fossil elephant molar                                               (Tham Huai Khang Khao)

Porcupine spines and tracks (Hystrix spp.)                (Tham Huai Khang Khao)

                                                                              (Tham Men ["Porcupine Cave"])

Rhinolophus bats (at least two different species)

Bamboo Rat (Rhizomys sinensis)                                                (Tham Nam Lod)

REPTILES & AMPHIBIANS

Cave Racer Snake (Elaphae taeniura)                        (Tham Kraduk)

                                                                              (Tham Ngu)

Unidentified tube-nosed turtle                                    (Tham Khlong Wat)

Frogs & Toads (pigmented surface species)               (All stream caves)

Banded geckos                                                       (Tham Men ["Porcupine Cave"])

FISH

Fish (surface species, pigmented with eyes)              (All stream caves)

Catfish (surface form)                                               (Tham Khlong Wat)

INVERTEBRATES

Crabs (Pale orange)                                                 (Tham Khlong Wat)

                                                                              (Tham Huai Khang Khao)

Huntsman spiders                                                    (Tham Men ["Smelly Cave"])

Tarantula spiders                                                     (Tham Men ["Porcupine Cave"])

Ixodid ticks

Millipedes (white and pigmented)

Crickets (white)

Cockroaches

Whip Scorpions

Amblypygides

Shrimps

Diptera larvae

Glow-worms

SURVEY NOTES

All the surveys were to BCRA Grade 3b unless otherwise stated.  Bearings and inclinations were measured using a hand held Suunto compass and a hand held Suunto clinometer both of which were read to the nearest degree. Distances were measured using a 30m fibron tape measured to the nearest 5cms.

The survey data was processed and a centre line plotted using "COMPASS" software.

The UTM co-ordinates for the cave entrances were obtained by using a GARMIN "12XL" hand held GPS receiver.  Because of the difficulty of using these instruments in thick jungle terrain in some cases a rough surface survey was made to the nearest clearing where the requisite number of satellites for an accurate fix could be located by the GPS.

So for .....

THAM HUAI KHANG KHAO the cave entrance is approximately 100m from the UTM coordinated position on a bearing of 050deg. mag. 

THAM HUAI SIT 1&2 and THAM MEN the cave entrances are approximately 500m from the UTM co-ordinated position on a bearing of 045deg. mag.

The cave plans published in this report are intended as a map for future explorers. There is sufficient information provided to ensure that there is no unnecessary duplication of the work already done. Plan view has been used throughout, as there is little significant vertical range in any of the caves surveyed.  If further details are required then please contact the expedition members.

CONCLUSION

In a period of less than two weeks four cavers with help from the employees of the Royal Forestry Department mapped and photographed over 2.7 Km of cave passage.  Because of the constraints of time efforts were concentrated mainly on the easily accessible resurgence caves.  However, information from the National Park Rangers indicates that there are many other sites worthy of investigation.  In addition, topographical maps of the region show a number of streams sinks in the higher parts of the park with considerable scope for both long and deep cave development.

Besides sporting interest, the caves provide a home to many species of animals including a rare species of bat.  They contain potentially important palaeontological and palaeozoological data - as evidenced by the fossilised elephant's tooth.

This short reconnaissance trip has shown that there is significant potential for further speleological exploration in the Tai Romyen National Park.  It is vital that these caves are mapped and surveyed so that they can be integrated into the overall management plan for this beautiful area.

GEOLOGICAL MAP