Mount Kinabalu is essentially a massive pluton formed from granodiorite which is intrusive into sedimentary and ultrabasic rocks, and forms the central part, or core, of the Kinabalu massif. The granodiorite is intrusive into strongly folded strata, probably of Eocene to Miocene age, and associated ultrabasic and basic igneous rocks. It was pushed up from the earth's crust as molten rock millions of years ago. In geological terms, it is a very young mountain as the granodiorite cooled and hardened only about 10 million years ago. The present landform is considered to be a mid-Pliocene peneplain, arched and deeply dissected, through which the Kinabalu granodiorite body has risen in isostatic adjustment. It is still pushing up at the rate of 5 mm per annum. During the Pleistocene Epoch of about 100,000 years ago, the massive mountain was covered by huge sheets of ice and glaciers which flowed down its slopes, scouring its surface in the process and creating the deep Low's Gully (named after Hugh Low) on its north side. Its granitic composition and the glacial formative processes are readily apparent when viewing its craggy rocky peaks.