For ages, people believed that Earth would always be the same. Now we realize that it is constantly changing.
The mighty Himalaya Mountains in South Asia, with their record-breaking heights, are still growing. The great Alps in Europe may grow taller still.
On the other hand, the Rocky Mountains in the United States are continuing to wear away, just as the eastern Appalachians have diminished over time.
These changes, however, generally take place at the rate of a pebble, a rock, or a boulder at a time.