Why Are Mountains So High?

Imagine mountains as boats floating in water. The water is the soft rock deep inside Earth, and the mountain is the heavy boat. If you add too much weight to the top of a boat, it sinks lower until it sits just right at the surface. Mountains work the same way! They are chunks of light crust pushing up against the heavy mantle. When they get too tall, gravity pulls them down and they start to sink or spread out sideways. Erosion also helps by wearing away the top like a sandpaper. So, there is a maximum height where the mountain balances perfectly between being pushed up and pulled down. That is why Everest is high but not touching the sky.