Sunday, December 22, 2013

The sculpturing of Mount Kinabalu

ADMIRING the sheer size of this mountain from several vantage points in Sabah, it was only in Kundasang that my eyes focused on the crenulated notches on the bare granite skyline and on the mounds of small forest clad hills on the lower slopes.

How does one explain the rugged peaks of Mount Kinabalu, symbolised by such wonderful names as Donkeys Ears, The Rabbit, The Ugly Sisters and the peaks of St John, Victoria, King George, Tunku Abdul Raman and the South and North Peaks? Yet, what of Low’s Peak and Low’s Gully?

From their extensive research on the mountain’s superficial deposits, Koopmans and Stauffer, at the University of Malaya, in 1966, estimated that during the Eurasian Ice Ages (the Pleistocene period in geological time) 1.4 million to 10,000 years BP (Before the Present), Mount Kinabalu was covered by an ice cap, 5km square in area.

From the edges of the ice cap ice lobes in the form of glaciers flowed down slope exploiting fault lines in the underlying granite-type rock. Slowly but surely the loose rocks embedded and frozen into the base of these glaciers abraded the granite surfaces over which they rode.

Evidence of glacial erosion may be seen today in the striations (chisel-like scratches) in the granite surface zigzagging across the upper plateau surface.

Through the pressure of the overlying ice, the rocks embedded in the base of these glaciers frictionally sanded and eroded the bedrock.

Interestingly these striations bisect each other at distinctive angles suggesting that at different stages of the Pleistocene era the glaciers on Mount Kinabalu came from different directions.

The deeper scratches are relics of more recent glacial advances and the shallower striations from earlier ice advances. It is likely that ice exploited a major fault in the granite that led to a huge icefall in the form of a glacial spillway from the ice cap, thus creating the 1,500 metre sheer drop of Low’s Gully, best observed from Low’s Peak.

The smoothness of the upper mountain, in the area of the fixed ropes, and the glacial shutes where the ice spilled downwards add further evidence of glacial erosion.

In stark contrast, the jagged skyline, best observed on a clear day from Kundasang or Ranau, poses yet a separate explanation. At the peak periods of the Pleistocene glaciations the rock protuberances of Low’s Peak, Donkey’s Ears and The Rabbit were all above the uppermost level of the ice cap.

Such upstanding features are known as nunataks (an Inuit term for bare rocks extending beyond the upper limit of the Greenland ice cap). These peaks experienced freeze-thaw action by night and day, when in daytime, the ice in the cracks in the granite melted only to allow the water to trickle deeper into a crack.

At night-time the water refroze with the new ice expanding by 9 per cent of the water’s volume thus widening the crack. Repeated freeze-thaw cycles shattered the granite into angular shaped fragments.

Continue reading (Incl. Pics) at: The sculpturing of Mount Kinabalu