WHAT IS MOUNT EVEREST?
Why is the Everest the highest mountain on earth?
Generally, the geology of Mount Everest is very simple; the mountain is a huge slice of solidified sediments that once lay at the bottom of the Tethys Sea. The rock layers found on Mount Everest are limestone, marble, shale, pelite and crystalline rocks belonging to the basement. They were divided into three rock formations. From the mountain base to the summit they are: the Rongbuk Formation, the North Col Formation and the Qomolangma Formation. These rock units are separated by faults, one near the top of Everest, the other in the vicinity of Base Camp, both dipping north at low angles. Below them are older rocks including granite, pegmatite intrusions and gneiss.
The Rongbuk Formation composes the basement rocks below Mount Everest. The metamorphic rock includes schist and gneiss. Intruded between these old rock beds, there are great sills of granite and pegmatite dikes.
The complex North Col Formation, located between 7,000 and 8,600 meters high, divides into several distinct sections. The upper 400 meters forms the famous “Yellow Band”, a rock band of marble, phyllite (with muscovite and biotite), and semi-schist (a slightly metamorphosed sedimentary rock). Below the Yellow Band there are more alternating layers of marble, schist, and phyllite. The lower 600 meters is composed of various schists formed by metamorphism of limestone, sandstone and mudstone.
At the bottom of the formation is the Lhotse detachment, a thrust fault that divides the North Col Formation from the underlying Rongbuk Formation.
The Qomolangma Formation, contains the highest rocks of Mount Everest. It is formed by layers of Ordovician-age limestone, recrystallized dolomite, siltstone, and laminae. The formation starts at 8,600 meters at a fault zone above the North Col Formation and ends on the summit. It has many marine fossils, including trilobites, crinoids and ostracods.
But, why is Everest the highest mountain on earth?
Ok, this statement is relative from the point of view. If you take the measurement from the base, an island-volcano is almost twice as tall as Mount Everest. The Mauna Kea in Hawaii has a height of 10.200 m but his base is at the bottom of the sea. While the Everest is only 5.000m from its bottom.
Also, recently we found that “El Chimborazo” volcano in Ecuador, is the farthest point from the center of the Earth. The point closest to outer space. Nevertheless, the Everest is the highest point at sea level. That’s why it keeps its mountain status higher from base level.
How do you explain this?
The Earth is flatter at the poles and thicker in the equator. The radius difference between the poles and the equator is 21 kilometers.
They are also different from their formation, we already know how to form Mount Everest, but Mauna Kea in Hawaii is a hot spot, this formation is by magma that rises directly from the mantle, and the volcano El Chimborazo in Ecuador is due to the subduction of the Nazca plate with South America.
Now, the next time you talk about the highest mountain on earth you must be clear what you mean.