S16
Mountains as pegs
"Have We not made the earth a resting place? And the mountains as stakes?" (78:6–7): the verse pictures mountains as the pegs of a tent, holding the earth steady as a home.
أَلَمْ نَجْعَلِ ٱلْأَرْضَ مِهَٰدًا٦ وَٱلْجِبَالَ أَوْتَادًا٧
Transliteration: alam najʿali l-arḍa mihādan · wal-jibāla awtādan
Have We not made the earth a resting place? And the mountains as stakes?
وَأَلْقَىٰ فِى ٱلْأَرْضِ رَوَٰسِىَ أَن تَمِيدَ بِكُمْ وَأَنْهَٰرًا وَسُبُلًا لَّعَلَّكُمْ تَهْتَدُونَ١٥
Transliteration: wa-alqā fī l-arḍi rawāsiya an tamīda bikum wa-anhāran wasubulan laʿallakum tahtadūna
And He has cast into the earth firmly set mountains, lest it shift with you, and [made] rivers and roads, that you may be guided,
وَٱلْجِبَالَ أَرْسَىٰهَا٣٢
Transliteration: wal-jibāla arsāhā
And the mountains He set firmly
Translation: Saheeh International
offered as evidence for the Day of Judgement.
"And He has cast into the earth firmly set mountains, lest it shift with you, and [made] rivers and roads, that you may be guided" (16:15), Meccan.
"And the mountains He set firmly" (79:32), Meccan.
Key words
Mihād (78:6): a bed, a resting place. Awtād (78:7): tent pegs. Rawāsiya (16:15): firmly set, anchored. An tamīda bikum: "lest it shift with you".
The image
A tent is pitched on open ground; its pegs hold it down so it does not move in the wind. The verses use that picture for the earth as a home for people.
See also: 21:31 , 31:10
Classical tafsir
Ibn Kathir on 78:6–7. The earth is "an established, firm and peaceful resting place that is subservient to them." The mountains: "He made them as pegs for the earth to hold it in place, make it stable and firm", "so that it may be suitable for dwelling and not quake with those who are in it."
Al-Jalālayn on 78:7. The mountains are pegs with which "the earth is tied down like tents are tied down with pegs."
Ibn Kathir on 16:15. The mountains "keep it from shaking in such a manner that the creatures dwelling on it would not be able to live."
Al-Jalālayn on 16:15. "lest it should shake move with you".
Ibn Kathir on 88:19. The mountains "are firmly affixed so that the earth does not sway with its dwellers."
What they share, and what they did not say. All read the mountains as giving the earth stability as a dwelling place, so that it does not move "with" its inhabitants. Ibn Kathir's phrase "would not be able to live" frames this as habitability. Neither commentary mentions mountain roots or plate tectonics.
How it works
Each point is tied to "stakes" and "firmly set".
- Mountains have roots. Established Isostasy is "the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle": the crust "floats" at a height set by its thickness and density (Wikipedia). In the simple Airy model, mountain "roots will be about five times deeper than the height of the mountains", so an 8 km mountain would have a root about 32 km deep (Wikipedia). Crust in continental collision zones can reach about 80 km, against about 40 km for average continental crust (Wikipedia).
- How the roots were found. Established Plumb lines near the Andes and in India were pulled sideways by mountains "less than expected"; in 1855 George Airy and John Henry Pratt each proposed an explanation: Airy, roots of lighter crust beneath the mountains; Pratt, that the crust under mountains is less dense (Wikipedia).
- But mountain belts are earthquake zones. Established The Himalaya formed, and is still forming, as the India and Eurasia plates converge "at a relative rate of 40–50 mm/yr"; "Northward underthrusting of India beneath Eurasia generates numerous earthquakes", making the region "one of the most seismically hazardous regions on Earth" (USGS). The same collisions that raise mountains cause earthquakes.
Points of awe
In the Airy model, the hidden root is about five times deeper than the mountain is tall (Wikipedia).
Text version
- Under isostasy, Earth's crust floats on the denser mantle, a bit like an iceberg in water. A high mountain range is balanced by a thick root of lighter crust pushing down into the mantle.
- In the simple Airy model, the root goes about five times deeper than the mountain is tall. The drawing uses that ratio. Normal continental crust is 30–40 km thick; it is drawn here at 35 km.
- The drawing is schematic: only the vertical scale is to scale; the shapes of the mountain and its root are illustrative. The Airy rule describes broad ranges, not single peaks.
- Under the Himalaya and Tibetan Plateau, the crust is about 70–75 km thick (some studies say up to 80 km).
- Honest note: mountains do not prevent earthquakes. The plate collisions that raise mountains also cause quakes.
Reflection
The verse speaks of something everyone in a desert camp knew: a tent stands because of its pegs. "Have We not made the earth a resting place? And the mountains as stakes?" (78:6–7). The earth is pictured as a home pitched for us, held down so it does not blow away.
Ibn Kathir draws the point: the earth was made "suitable for dwelling". Al-Jalālayn keeps the picture: the earth "is tied down like tents are tied down with pegs". The verses are about a home made steady enough to live in.
Modern geology adds something the first listeners could not see. Mountains do have roots: most of a mountain's mass lies hidden below, balancing what rises above. A peg is mostly underground too.
But the verse is not a lesson in seismology, and it should not be made into one. Mountain belts are where many earthquakes happen. The verse's own promise is wider: that the ground under our feet, on the scale of a human life, is a place where we can build, plant and sleep. We rarely think of that as a gift until it shakes. The verse asks us to notice it while it is still.
Questions readers ask next
Do mountains really have roots?
Yes. Under isostasy, high mountains are balanced by thick roots of lighter crust; in the Airy model, about five times deeper than the mountain is tall (Wikipedia).
Do mountains prevent earthquakes?
No. Mountain belts are earthquake zones, because the same plate collisions build mountains and cause quakes (USGS).
Then what does "lest it shift with you" mean?
The commentators read it as the earth being made a stable home: so that it does "not quake with those who are in it" and its creatures can live (Ibn Kathir).
What are awtād?
Tent pegs. Al-Jalālayn: the earth "is tied down like tents are tied down with pegs."
Sources
- Saheeh International — 78:6–7, 16:15, 79:32, 15:19, 88:19.
- Ibn Kathir, Tafsir (abridged English), and Tafsīr al-Jalālayn (English), on 78:6–7, https://surahquran.com/tafsir-english-aya-7-sora-78.html, and on 16:15, https://surahquran.com/tafsir-english-aya-15-sora-16.html; Ibn Kathir on 88:19, https://surahquran.com/tafsir-english-aya-17-sora-88.html.
- "Isostasy", Wikipedia, https://en.wikipedia.org/wiki/Isostasy.
- USGS, Seismicity of the Earth 1900–2010: Himalaya and vicinity, Open-File Report 2010-1083-J (2013, revised 2014), https://pubs.usgs.gov/publication/ofr20101083J.
- "Allah created the mountains stable to stabilise the earth and prevent it from moving and shaking", IslamQA, Question 223428, https://islamqa.info/en/answers/223428 — the popular modern claim.
- Wikipedia, "Isostasy" (with references)
- University of Alberta lecture notes on Airy isostasy and Tibetan crust (75–85 km)
- MIT OpenCourseWare 12.002, isostasy lecture
- Ibn Kathīr and al-Qurṭubī on 16:15 and 78:7