GEOLOGY OF MULU CAVES
Gunung Mulu National Park is famous for its limestone karst formations. Features include enormous caves, vast cave networks, rock pinnacles, cliffs and gorges. Mount Mulu is a sandstone mountain rising to 2,376 m (7,795 ft).
Gunung Mulu National Park has the largest known natural chamber or room – Sarawak Chamber, found in Gua Nasib Bagus. It is 700 m (2,300 ft)) long, 396 m (1,299 ft) wide and at least 70 m (230 ft) high. It has been said that the chamber is so big that it could accommodate about 40 Boeing 747s, without overlapping their wings. The nearby Deer Cave is one of the largest single cave passages in the world.
Other notable caves in this area are Benarat Cavern, Cave of the Winds, and Clearwater Cave, the 8th longest cave in the world (May 2014) and believed to be the largest cave in the world by volume at 30,347,540 m3 (1.071713×109 cu ft).
Mulu’s limestones belong to the Melinau Formation and their age is between 17 and 40 million years (Late Eocene to Early Miocene).
Stratigraphically below the limestones, and forming the highest peaks in the south east sector of the Park including Gunung Mulu, lies the Mulu Formation (shales and sandstones). The age of these rocks is between 40 and 90 million years (Late Cretaceous to Late Eocene).
GEOLOGY OF WIND CAVES
The Wind Cave Nature Reserve is part of the Bau Formation, a narrow belt of limestone covering about 150 sq km of Southwest Sarawak. Due to the comparatively soft and soluble nature of limestone, and the intense tropical rainfall of the region, the whole of the Bau Formation is intersected with caves. Whilst many caves of the Bau Formation are remote and inaccessible, the Wind Cave is within easy reach of Kuching and is a popular day trip and picnic destination. The Wind Cave Nature Reserve covers 6.16 hectares and includes the cave itself and the surrounding forest.
GEOLOGY OF NIAH CAVES
Many million years ago (from about 23 million years ago), much of what is now Niah National Park was coral reef. Over 5 to 10 million years, the reef grew thicker and thicker, until it was over 800m thick – a massive deposit of limestone formed by the skeletons of billions of dead corals. Earthquakes and uplift over about 2 million years then lifted this huge reef above the surrounding land, forming Gunung Subis – the mountain system which forms the core of Niah National Park today.
The limestone is quite soft and readily soluble in rainwater. Erosion from rain and streams over the past 3 million years has cut some massive cave systems into the mountain; and those caves have become the home of numerous animals – and intermittently for the last 40,000 years, humans as well.