sign in a cave in Laos

22 August 2008

Living Caves (Nature Watch 1997)

Caving enthusiast Liz Price sheds light on
L i v i n g C a v e s

Some of the most spectacular and 'youngest' caves in the world
are in Sarawak and they are a mere 10 to 20 million years old.
And these caves are not only `alive' but still growing!

Caves are made of solid rock and yet some caves are still alive and still forming!

In caves the world over, and in the caves that riddle the hills and mountains of Peninsular and East Malaysia (notably Sarawak), stalagmites and stalactites and other sculptural cave wonders are continuously being formed and exquisitely shaped by a common yet wonderous life-giving substance. It is none other than water -- the
substance that, like air, gives us life.

Yes, as long as there is water present in a cave, the cave will continue to develop.

Just reflect on this. Caves are millions of years old and yet they are alive and still growing!

Think too, that while Man has landed on the moon and prepares to explore Mars, there are still many caves left on Mother Earth that have yet to be discovered and explored. And in case you think that a cave is just a space in the side of a hill, know that it is far more than that. Mother Nature has carved out some marvellously intricate cave systems and some of these meander hundreds of kilometres deep
into the mountains. What has been discovered so far has merely scratched the surface of this Planet.

The longest known cave in the world is Mammoth Cave in the USA. It is 560 km long. Clearwater Cave in Mulu, Sarawak, is the longest known cave in Asia. At 107 m, it is the 10th longest in the world.

And what marvels lie in these cave systems! Over thousands of years, Mother Nature, using that wondrous element water, has hollowed out huge chambers and passages and gouged out river-beds. She has also built up and shaped the stalactites that hang like chandeliers from the 'ceilings' and stalagmites that grow up from the cave floor. Some caves support colonies of animal life, few of which are known in the sunlit environment outside the caves.

One can trace the origins of caves to the life that began at the bottom of the sea.

Over million of years, as shells, corals and sand were deposited on the sea bed, they formed what we know as limestone. Layer by layer the limestone was built up and compacted. Then, when Earth underwent a period of orogeny or uplifting, these layers of limestone became hills and mountains which rose above the sea.

These mountain ranges, though formed of a hard substance (limestone) are easily corroded by natural acids. These acids are produced when falling rain picks up carbon dioxide from the air. Then, as the rain water percolates through the soil, it absorbs more carbon dioxide. When this acidic water comes into contact with the
limestone it begins to attack it and, finding small holes, seeps down through the rock, gradually enlarging cracks.

Over the years -- and here we mean thousands and millions of years -- the cracks became passages winding through the mountains.

Do you know, too, that while water mixed with carbon dioxide becomes corrosive, eating up the limestone, at the same time the water is taking in calcium carbonate (from the limestone), and when exposed to air this saturated water becomes a building substance?

The calcium-enriched water forms deposits which, over time, build up into beautiful stal, that is, stalactites and stalagmites. On average, a stal grows about 1 cm in 60 years and encountering stals 10 or 20 cm high (or more) is common in Malaysia's caves, so one can easily believe geologists who estimate the age of the limestone caves in Peninsular Malaysia to be between 60 to 100 million years old.

But while this makes the caves ancient, the actual limestone rock is estimated to be much older, about 345 and 440 million years old, and this estimate is based on the fossils that have been found in the Carboniferous-Silurian rock.

It seems odd then to learn that the rock, and therefore the caves of East Malaysia (i.e. Mulu and Niah), are relatively much younger than the caves and rock of the Malaysian mainland. Niah rock is lower Miocene and is therefore about 20 million years old. Mulu, with its large cave system, is only about 10 million years old. And though the caves of Peninsular Malaysia are much older, the longest known cave there is only 3.4 km long. It is in Perlis.

Caving in this part of the world is made more exciting by the knowledge that Mulu holds the record for the world's largest underground chamber. This is the Sarawak chamber in Gua Nasib. It is roughly 600 m long and 400 m wide which makes it large enough to house eight Jumbo jets nose to tail, with room for another 32 jets at the
side. Or, put another way, the Sarawak chamber can fit in 20 international size football pitches.

Nor is Mulu merely spectacular. It holds a mystery to marvel at and mull over for, according to engineers, the Sarawak chambers should not exist because the rock, by their reckoning, is not strong enough to support such an enormous roof span!

What this means is that Man -- even with the latest state of the art technology -- cannot build the 10 million year-old Sarawak chamber. Only Mother Nature in her infinite wisdom has.

Further more, Mulu holds yet another spelacological record. It has the biggest cave passage. This is in the Deer Cave and this passage is 1.2 km long and averages over 100 m high. And in some parts it widens to over 160 m.

C A V E A R T A N D A R T I F A C T S :
K E Y S T O M A N ' S P R E H I S T O R I C P A S T

The more accessible caves in the world today are `show caves', open to the public. But prehistoric man (caveman) used caves as their homes, sturdy natural shelters from the weather, and also from wild animals. Traces of human remains in caves -- their tools, their artifacts and their art, carved or painted on rock -- give rich clues as to the lives they led in those nomadic times.

It is impossible to give irrefutable evidence of man's earliest use of caves for even so-called experts only dare venture dates that can have as much as a 30 million year variance ("the Peninsular Malaysia caves were themselves formed about 60-100 million years ago"), but what is for certain is that many tribal cultures, the world over, used caves first as shelters and later as temples for worship and meditation and even as burial sites. Then, in times of war, persecution or inter-tribal conflict, caves were used as hideouts.

Those who have never ventured into caves other than `show caves', probably have the impression that most caves are pitch-dark, damp, dank and smelly places, rife with bats, poisonous snakes, scorpions and other `creepy crawlies'.

Some of this is true but at the same time caves are beautiful and peaceful places and home to some incredible creatures. Venture beyond the entrance of a deep cave and you enter into a nocturnal world of infinite variety that is fascinatingly different from the world outside.

However, there are some distinct differences between caves in temperate climates and caves in the tropics. Tropical caves are generally bigger, above ground and therefore less vertical, warmer and with much more fauna.

C A V E I N H A B I T A N T S A R E U N I Q U E . . .

Temperate or non-tropical, caves are well and truly dark which is why glow worm caves like those in New Zealand, are particularly enchanting. There is no sunlight in the cave and therefore no plants as plants needs sunlight to photosynthesise. These make cave inhabitants quite unique and they are divided into two types. One is
the `trogloxenes' and the other the `troglobite'.

Trogloxenes use the caves as temporary shelters (cave men being one of these), but they can also live outside. Troglobites spend their whole life in the cave and every troglobites is dependent on the cave dwelling bats for their very survival.

Bats and swiftlets are the only cave dwelling animals that go out to feed; and it is the bat's excreta or guano which supports the entire cave dwelling food chain.

The bats live suspended from the roofs of the caves and their guano falls onto the cave floor, forming rich food for insects like beetles, mites, worms, cockroaches etc. These insects are in turn fed upon by spiders, crickets, centipedes, pseudo-scorpions and the like. And these creatures are then hunted and eaten by frogs and toads.

Snakes also live in caves and the non-poisonous Cave Racer, Elaphe taeniura, is the only snake that has adapted to cave life and it feeds on bats, thereby completing the food chain. Bats are also useful to the life outside the cave. Bats pollinate the durian and petai trees, as well as other fruit trees. The bat guano is a rich fertiliser but the practice of collecting it should be discouraged as it disturbs the delicate ecosystem in the caves.

Small mammals such as rodents can also be found in caves, also porcupines and occasionally elephants will visit a cave entrance, presumably to lick the salts there. But the main cave life is made up of invertebrates.

In Dark Cave (Batu Caves, outside Kuala Lumpur), 170 species of invertebrates have been found. This includes one of the world's rarest spiders, the Trapdoor Spider, Liphistius batuensis, aptly named after the Batu Caves. It is thought that this species is unique to Dark Cave as it has not been found anywhere else in the
world. At least not yet.


As with everything else in the natural world, caves have provided man with shelter and refuge but despite their solid rock appearance, caves and the cave environment are fragile and man can and has destroyed the world of millions of years in mere seconds. Many caves have been destroyed through quarrying for the limestone which is used in the construction industry.

All caves need to be protected; this goes not just for the caves that are alive and still forming but even those that appear to be dry and 'dead'.

While one would like people to appreciate the special atmosphere of caves and their particular beauty, caves need to be protected from tourist hordes. The fantastic formations, underground streams and myriad animal life can be harmed, polluted and damaged by the unwary human visitor. For instance I have seen ignorant people break off a stal to take home as a sourvenir, only to find when they get outside the cave that what had appeared ethereal and beautiful turns out to be
only an "uninteresting" lump of rock. So it is important not to break off or even to touch the formations, bearing in mind how many thousands of years each has taken to grow.

The other human activities that are even more immediately threatening are the taking of guano for fertiliser and, even worse, the rapacious removal of swiflets' nests on a commercial scale for soups and medicines. This takes place mostly in Sabah and Sarawak and the harvesting of the nests hurts not only the birds but the caves.

Caves must be appreciated as an unique part of the natural environment, in any part of the world. Caves are also one of the last few places left "to go where no man has been before" as there are many caves waiting to be discovered. And who knows what rich secrets their discovery will yield?

Nature Watch, January-March 1997. [Singpaore]

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