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Gomantong Caves, Sabah


Figure 1. Distribution of the Gomantong Limestone in eastern Sabah, showing limestone outcrops and location of the Gomantong Caves. After Noad (2001).


Gomantong Caves , entrance to Simut Hitam (or Black Cave)

Gomantong Caves are developed in Gomantong Hill, an isolated limestone mogot in the Kinabatangan region some 30 km south of Sandakan, eastern Sabah (East Malaysia) on the Island of Borneo (Figure 1).  The caves are developed in the Cenozoic Gomantong Limestone dated as Late Oligocene (Chattian) to Lower Miocene (Burdigalian) or c. 25-16 Ma (Boudagher-Fadel and Noad, 2000; Noad, 2001). These limestones were deposited in an open marine shelf setting, adjacent to an east-west trending shoreline.


Simut Hitam (Black Cave)

The large tourist cave is called Simut Hitam (or Black Cave) and houses large colonies of black-nest swiftlets, and bats. Another longer, but volumetrically smaller cave, Simud Puteh (White Cave), forms the other main part of the Gomantong Caves system.

The Gomantong Caves, like many large limestone caves in Borneo (e.g. Niah Caves) are amongst the most famous in Southeast Asia and have for centuries been exploited as a valuable source of guano and swiftlet nests (for 'birds nest soup').  It was perhaps Sir David Attenborough's famous documentary, with him seen wading through guano mounds seething in beetles and cockroaches, that thrust Gomantong Caves into the global layperson's spotlight. Having similarly waded through these mounds of guano-based organisms at Gomantong, I can certainly attest to this rather undesirable experience, but perhaps what hits one more poignantly, is the incredible stench of rotting guano, cockroaches, bats, swifts and other living and dead and decaying cave organisms that deter many a tourist from venturing beyond a few meters into the cave.  This cave in particular is notable for the millions of cockroaches it houses and these are found inhabiting not only the guano mounds but every wall and nook and cranny of the caves.  Many cockroaches have lost their pigmentation due to life in the dark and their huge numbers are preyed upon by large poisonous Scutigera Centipedes. Walking through the cave one is subject to organic debris from above, including baby or dying bats and swifts.  One of the more bizarre experiences I had at Gomantong was watching several fresh-water crabs in the small stream that flows through the cave fighting over the fresh corpse of a bat!


Baby bat that fell on to my ruck sack at Gomantong Caves


Cockroaches on the cave wall at Gomantong. Note white ones that have lost their pigmant due to the dark environment.


Large Scutigera Centipede at Gomantong

All this biomass in the caves has taken its toll and it has been estimated that as much as 70–95% of the total volume of the modern Gomantong Caves may have been opened by direct subaerial biogenic dissolution and biogenically-induced collapse, and by sub-cutaneous removal of limestone, over a period of 1–2 million years (Lundberg and McFarlane, 2012).

References

Boudagher-Fadel, M., Noad, J.J., 2000. Larger Foraminifera from Late Oligocene-earliest Miocene reefal limestones of North East Borneo. Rev. Esp. Micropalaeontol. 32, 341-361.

Noad, J.J. 2001. The Gomantong Limestone of eastern Borneo: a sedimentological comparison with the near-contemporaneous Luconia Province. Palaeogeography, Palaeoclimatology, Palaeoecology 175, 273-302


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