Earth's crust has been slowly moving for billions of years. Not only mountains are slowly moving but also whole continents.
50 years ago, "continental drift" was a fringe hypothesis rejected by most geologists. Today the theory of plate tectonics (which includes continental drift) is universally accepted as true, and unifies once-separate areas of geology under one grand banner. There are mountains of evidence (literally) that plate tectonics has taken place in our planet's past.
National Geographic, How Do We Know The Continents Are Moving?, 2014
Whole contionents are moving. This was known recently. But 1400 years ago the Quran said that mountains move:
[Quran 27.88] You see the mountains and think they are firmly fixed: but they are moving away just like the clouds are moving away: (such is) the artistry of Allah, Who disposes of all things in perfect order: for He knows all what you do.
How could an illiterate man who lived 1400 years ago have known that mountains move?
(The Christian Bible says that Earth is fixed on top of pillars 1 Samuel 2:8)