One Day We shall remove the mountains, and thou wilt see the earth as a level stretch, and We shall gather them, all together, nor shall We leave out any one of them.
Quran 20: 105-109
The following excerpt is taken from “The Holy Quran in Today’s English” by Yahiya Emerick under the commentary of the above verse (20: 105-109):
Now they’re asking you about the mountains – (will they really be crumbled to nothing)? Say to them, “My Lord will pull them out from their roots and scatter them like dust,  leaving a smooth, level plain behind.  Nothing bumpy will you see, nor anything uneven remaining there.” 
*It’s interesting that the Qur’an puts forward the notion that mountains have roots. This was not something that was known in the ancient world and is an accurate description of actual geologic structures found deep under mountain ranges and rooted in the activities of plate tectonics.
The Prophet said, “On the Day of Judgment, all people will be gathered on a white (featureless), flat land that looks just like a piece of wheat bread, for it will have no landmarks anyone can recognize.” (Bukhari, Muslim)
On that day, (all people) will follow (the voice of) the caller without deviation. All noise will be hushed in the presence of the Compassionate, and you’ll hear no more than the sounds of shuffling feet.  On that day, no one’s intercession will do any good, save for those who were given permission (to intercede) by the Compassionate, and whose speech is acceptable to Him. 
Emerick, Yahiya. The Meaning of the Holy Qur’an in Today’s English (p. 829). Unknown. Kindle Edition.