Members of a Royal Geographic Society expedition surveying the Sarawak Chamber soon after it was discovered. It is estimated that the chamber is large enough to fit 40 Boeing 747s. — All photos by ANDY EAVIS
Scientists and cavers who are members of Britain’s Royal Geographic Society have led 20 expeditions into the depths of Mulu Caves near Miri, Sarawak, since the 1970s and explored over 500km of trails.
In those years, they have discovered underground rivers and caverns, including the Sarawak Chamber, one of the largest in the world by area, as well as a Garden of Eden and photographed Abraham Lincoln’s distinctive profile on the 154m-high entrance to the Deer Cave.
But apparently, that’s not quite enough for ardent speleologist Andrew James Eavis.
Come November 2021, and barring any new Covid-19 triggered restrictions, the 73-year-old Briton will be part of a team mounting a new expedition into the Mulu Caves.
“I am heading there this autumn with a large expedition, coronavirus and lockdown permitting, to continue the exploration and scientific study of these wonderful caves.
“Who knows what there will be round the corner?” says Eavis, whose work has been instrumental in discovering, among others, the world famous Sarawak Chamber.
The interior of Deer Cave, looking our towards the entrance with water falling from the roof reflected in the light. — 123rf.comThis time, the expedition will number 30 people, including five cave scientists who will be studying various aspects of the caves’ ancient history. “The other 25 people will be continuing their exploration and surveying and photographing the wonderful caves, ” he explains in an e-mail interview recently.
The last expedition by the society to the Mulu National Park took place between Dec 29,2019, and Jan 17,2020, during which expedition members explored and photographed caves and passages with such intriguing names like Troll Canal, Cream and Cheese, Blue Moonlight Cave, Sakai Cave and Deception Cave in Gunung Benarat. The Sakai Cave had not been explored since its discovery in 1984.
Together with other expedition members, Eavis has contributed for 40 years to the fields of geomorphology, hydrology and cave science in the mapping of Mulu caves.
From as early as 2011, his team has been using a technology that would be familiar to iPhone and iPad users today to scan and map the complex subterranean network in Mulu: LiDAR, or light detection and ranging. Nowadays, the technology is used in self-driving cars and augmented reality.
In 2018, Eavis was presented with the prestigious Merdeka Award for his outstanding contributions to the people of Malaysia. Besides his caving work in Sarawak, Eavis has also explored caves in France, Papua New Guinea, and Guangxi, China.
Speaking at a TEDxHull event in Britain in 2013, he said that he didn’t want to be an adventurer who travelled to the North or the South Pole, but an explorer – “I actually wanted to go to where men have never gone before.”
An expedition member examining a ‘Star of Api’, an unusual karst formation in a cave in Gunung Api.Uncovering Mulu’s marvels
The Mulu Caves, comprising a network of caverns and passages, sits in the 52,860ha Gunung Mulu National Park, slightly over 100km away from Miri; visitors can take a half-hour flight from Miri airport that lands on a single strip in the middle of a jungle.
The national park is the site where Australian backpacker Andrew Gaskell was lost for two weeks in 2016 while hiking before miraculously being found alive, and, recently, a place of contention between Penan and Berawan villages and a company over plantation concessions granted in the vicinity.
Designated a Unesco (United Nations Educational, Scientific and Cultural Organisation) Heritage Site in 2000, the park is a juxtaposition of lowlands on its western front and a series of spectacularly dramatic summits, waterfalls, ridges, gorges, caves and karst towers on the east, all of it surrounded by a teeming, unique ecosystem.
It’s an ecosystem that hosts, among others, 81 species of mammals, 270 species of birds – including the rare, endangered helmeted hornbill – 55 species of reptiles, 76 species of amphibians and 48 species of fish, as well as various species of plants, many of them endemic to the area.
Gunung Mulu, a sandstone and shale mountain topped with a mossy forest, is Sarawak’s second highest peak at over 2,370m.
Back in 1978, Eavis had been part of the first expedition mounted by the Royal Geographic Society (RGS) to the Mulu Caves. Coincidentally, before the invitation came to join the scientific rainforest expedition, he was already investigating the area using aerial photographs and researching in relevant literature.
“I was lucky enough to go with the RGS to the Mulu National Park in Sarawak in 1978 as one of the first speleologists to ever visit that part of the world.
“Five speleologists were on that trip, and we explored and surveyed over 50km of cave passage, much of it huge. This was something of a record, ” he recalls.
It was then that Eavis realised that Mulu was one of the finest areas for caves in the world.
“I have spent all of my life studying caves around the world and I know of no other place where there is this continuous historical story in such a pristine and unspoilt manner.”
Lasting well over a year, the first expedition to the Mulu Caves numbered some 150 people – mostly scientists at the top of their fields of specialisation – making the park one of the most scientifically studied rainforest areas in the world.
The first expedition was quickly followed by others; Eavis himself helped put together two follow-up missions, one in 1981 and another in 1984. Made up of about 16 speleologists, the expeditions explored and surveyed about 50km of cave passages, and it was in the middle of one of these trips in 1981 that the Sarawak Chamber was discovered.
From as early as 2011, Eavis's team has been using a technology that would be familiar to iPhone and iPad users today to scan and map the complex subterranean network in Mulu: LiDAR, or light detection and ranging. This is an illustration of the LiDAR scan of the Sarawak Chamber.When the news first broke, it made headlines in newspapers around the world, especially when it was estimated that the chamber is large enough to fit 40 Boeing 747s.
Home to thousands of twittering swiftlets and chittering bats, the chamber’s floor area of almost 700m by 400m is certainly one of the largest ever explored and it has probably the largest unsupported single-span roof in the world, man-made or natural.
“It is therefore quite unlikely to be exceeded as it must be just about as large as it is possible to exist in limestone rock, ” says Eavis.
Since then, there have been other discoveries, including Conviction Cave, which is accessible only via a hole in the ground in an area known as the Hidden Valley, in 2015.
Time capsule
While Gunung Mulu was formed in the Palaeocene-Upper Eocene age between 66 million and 34 million years ago, Gunung Api, Gunung Benarat and Gunung Buda on the park’s western flank are younger.
However, they are all hewn from the same karstic limestone that the cave system developed from when there was a tectonic uplift of the karst. And according to Eavis, the caves of Mulu were formed from the top down.
“The limestone passages were all formed by rivers running at valley bottom level, usually close to sea level. As the land has been uplifted over the last 10 million years or so, the caves have also been lifted and left high and dry, ” he explains.
This, he adds, has led to at least five distinct levels of passages from over 2,000m in elevation down to those formed nearly at sea level.
“The high-level passages get their entrances blocked by precipitation from the mineral rich waters, and you get a gigantic, sealed time capsule.
“The cavers are now climbing up inside the mountain, discovering these sealed systems one level after another.
“As you get higher, the passages get older and they contain a fantastic history of what has gone on on the planet over the last 10 million years or so, ” explains Eavis, underlining the caves’ importance in the geologic record.
All the stalagmites and stalactites can be dated, as well as the sand and silt sediments.
“All of these deposits have inclusions of water and air, also carbon and pollen, even some bacteria. From careful study, history can be unravelled, ” he says.
Eavis climbing down into a cave during one of the expeditions.
The tough get going
In 1978, the Mulu caves expedition had to contend with complete wilderness – there was neither an airstrip nor logging roads then, and base camp was a three-day journey by boat from Miri town. While the upcoming expedition won’t have it as difficult, exploring the caves in Mulu remains challenging.
The surface topography, says Eavis, is difficult to traverse.
“Distances attained on the surface can be typically days per kilometre. The main reason why there are still so many caves left to explore is that it is very hard to get to the entrances on the surface. Usually, it is easier underground, ” he says.
While Peninsular Malaysia and Borneo have some of the most fantastic caves on Earth, Eavis laments that not many Malaysians are exploring them.
“On the Internet, there are a number of people mentioned who are actively looking at caves in Malaysia.
“It would be good if Malaysian caving becomes more organised and helps us continue exploring the country’s wonderful caves, ” he says, giving a nod to several institutions and organisations, including Malaysia Airlines, for funding and sponsoring expeditions.
“The finance of some of the science is covered by learned institutions but the main exploration has no direct sources of finance.”
Eavis says as a rough estimate, the 500km of trail explored so far is about half of the total length of cave passages that exist in Mulu although probably the largest of all chambers and passages have already been found.
“The beauty of cave exploration is you never know what is there until you actually find it. Currently, there is no way of predicting what may lie under the earth.”
