The Himalayas formed due to the collision between the Indian and Eurasian tectonic plates. Although the original collision occurred 40 to 50 million years ago, the Indian plate is still moving further north, causing the mountains to grow at a rate of approximately one to two centimeters a year.
When the two plates collided, the land in each began to fold and pile up on top of itself, as both plates were the same density and neither could slide underneath the other. The force of the collision resulted in the largest mountains on the planet, with the largest, Mt. Everest, rising to a height of more than 29,000 feet above sea level. Although they have only grown around nine kilometers in 50 million years, the current growth rate of the Himalayas equals an astonishing 10 kilometers for every million years. This means the Himalayas are currently growing faster than ever.
The Himalaya range stretches for more than 1,500 miles across the entire northern section of the Indian landmass. Prior to the collision, this landmass began as an island off the coast of Australia after the break-up of the Pangaea supercontinent, before slowly moving towards Asia over a period of several hundred million years.