Climbers who make it to the top of Mount Everest may not know it, but under the snowpack sits an expanse of mottled gray rocks that once lay on the ocean floor.

The rocks arrived at this surprising spot, nearly 30,000 feet above sea level, due to the slow march of tectonic plates, slabs of solid rock that make up our planet’s fractured outer shell. These plates continually jockey for position, shaping the array of features visible at the surface. In some places, the plates pull apart, creating valleys in the land. In others, they collide, shoving mountains into the sky.

Rising at the border of Tibet and Nepal, Mount Everest formed from a tectonic smashup between the