In setting up the argument for God's power to judge, the Surah uses the local understanding of the natural world in verses 6–7:
Surah 78:6-7:
Have We not made the earth a resting place [or couch]? And the mountains as pegs?
The word for pegs, Awtad, refers to the physical pegs used to hold down a Bedouin tent. This reflects a recurring Quranic claim (also in Surah 16:15 and Surah 21:31) that God threw mountains down onto the earth to act as weights so that the earth would not shake or tilt.
The Scientific Fact: Plate tectonics shows that mountains do not act as static "tent pegs" keeping a flat earth from shaking. In reality, mountains are the result of tectonic plates colliding and folding, and their root systems are deeply embedded in areas that are frequently prone to intense seismic activity and earthquakes.
This reveals a severe lack of scientific foresight. The author of the Quran looked at the horizon through the lens of a 7th-century desert nomad, comparing the vast earth to a flat tent floor and the visible mountains to the stakes holding it down.