Gunung Mulu National Park
Around 60 million years ago deep beneath the sea, one piece of the Earth’s crust began to slide up and over another piece of the Earth’s crust. For 20 million years rock grinding against rock produced a 5 km thick layer of sand which became cemented together as a deposit of sandstone known geologically as the ‘Mulu Formation’, but 40 million years ago it was still beneath an ancient sea teeming with sea life. Coral reef lagoons developed and over another 20 million years these lagoons were filled with layer upon layer of calcium carbonate mud formed from the soluble minerals found in seawater. Mixed with millions upon millions of minute sea shells the layers of calcium carbonate were compressed to become a 1,500 metre thick deposit of limestone known geologically as the ‘Melinau Formation’ and like all limestone it was formed in sea-water and it dissolves in fresh-water.
When the movement of the Australian and Asian landmasses caused the earth’s surface to buckle and fold about 5 million years ago, these sandstone and limestone formations were lifted high above the sea to create the mountains of Mulu and the relentless process of weathering by the elements now began to shape the landscape we see today.
As the rain falls on these limestone mountains, it passes through the soil and into the very small pores and cracks found in the limestone. Seeping and trickling through the limestone, the water gradually dissolves the rock, making these pores and cracks larger and larger to create a remarkable series of cave chambers and passages.
And here at Mulu you’ll find the biggest caves in the World!