Earth’s crust has been slowly moving for billions of years. Not only mountains are still slowly moving but also whole continents. Moslems say that this is what Allah says:
[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.
This verse deliberatly speaks about the mountains as they represent in the people’s mind the most imposing and stable natural elements on earth.
How could an illiterate man who lived 1400 years ago have known that mountains move?