When you hear “8,849 meters tall,” you might assume Mount Everest is a fixed number. It isn’t. The mountain is slowly growing - by about 4 millimeters a year. Surveyors and satellite measurements have confirmed it for decades. Why? Because the geological collision that built the Himalayas is still happening.
About 50 million years ago, the Indian subcontinent crashed into the Asian continent at the geological speed of about 5 cm per year. The thick crust of both landmasses had nowhere to go but up. Slowly, over tens of millions of years, the collision raised the Himalayas - the highest mountain range on Earth. The Indian plate is still pushing northward, just more slowly now, and the Himalayas are still rising.
Most years Everest grows by a few millimeters. But occasional earthquakes can change things suddenly: the 2015 Nepal earthquake was actually estimated to have slightly lowered the summit by a few centimeters, because seismic forces released some of the underlying pressure. Mountains might look permanent, but they’re really enormous geological clocks, ticking up and down over millions of years.
