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Why are Ordovician rocks found at the top of Mount Everest?

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Ordovician paleogeography — Ordovician Period The distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the Ordovician Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

The presence of Ordovician-aged rocks at the summit of Mount Everest is a result of the complex tectonic history of the Himalayan mountain range. These rocks are not native to the mountain's current elevation; rather, they are marine sedimentary rocks that were originally deposited on the ancient northern continental margin of the Indian subcontinent.1

During the Paleozoic Era, these sediments accumulated on the seafloor of the Tethys Sea. When the Indian Plate collided with the Eurasian Plate approximately 40 to 50 million years ago, the leading edge of the Indian continent was forced downward and subducted. During this process, slices of the ancient northern continental margin—including the sedimentary layers containing Ordovician material—were scraped off, folded, and thrust upward to the surface.231

Consequently, these ancient marine rocks were uplifted to extreme altitudes, forming the very tops of many peaks in the Great Himalayas as the range continued to rise.21