It took many years to determine the geology of Mount Everest; in other words, to establish its rock composition and geological history. Geologists have agreed to divide the rock structure of the highest peak in the world into three types of geological formations. Each one of them is separated from the other by low angle faults, which are fracture in the continuity of a layer of rock. Meanwhile, the formation and elevation of Mt Everest to the highest point (8,848 m) on the planet surface is, like the rest of the Himalaya, the result of the tectonic collision of the Indian plate against the Eurasian plate, which began about 40 million years ago, during the Tertiary period of the Cenozoic era.
The geology of Mount Everest tells us that this massif is composed of both sedimentary (limestone) and metamorphic rock arranged, as mentioned above, into three types of geological formations, which are kept apart from one another by faults. Thus, from the summit of Mt Everest to its base, these rock structures are the Qomolangma Formation, the North Col Formation, and the Rongbuk Formation. About 70 million years ago, these layers of rock used to be part of the sea bed of the extinct Thesys Ocean, long before the Indian-Australian plate began pushing north against the Eurasian plate.
Qomolangma Formation- It runs from the summit to the top of the yellow band (from 8,848 m to 8,600 m of altitude). It consists of Ordovician limestone, dolomite, and siltstone. The limestone of the summit is composed in turn of finely fragmented remains of trilobites, crinoids, and ostracods, ancient creatures that used to inhabit the ocean floor.
North Col Formation- It makes up the bulk of Mt Everest, with the Yellow Band constituting its upper portion. It lies between the 8,600 m and 7,000 m of altitude. The Yellow Band consists mostly of Cambrian diopside marble, which weathers to a distinctive yellowish brown. The remainder of the North Col Formation is composed of schist, marble, and phyllite, all three being metamorphic rocks.
Rongbuk Formation- It lies right under the North Col Formation, forming the base of Mount Everest. It is made up of sillimanite-K-feldspar grade schist and gneiss intruded by numerous sills and dikes of leucogranite ranging in thickness from 1 cm to 1,500 m (0.4 in to 4,900 ft). Leucogranite is granitic, igneous rock that is part of a belt of Late Oligocene–Miocene intrusive rocks known as the Higher Himalayan leucogranite. They formed as the result of partial melting of Paleoproterozoic to Ordovician high-grade metasedimentary rocks of the Higher Himalayan Sequence during the subduction of the Indian Plate.
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| South face of Mt Everest. Photo taken in May 1952 by the Swiss expedition. |
