The surface of the earth is broken into many rigid plates that are about 100
km in thickness. These plates float on a partially molten region called
aesthenosphere. Mountain formations occur at the boundary of the plates. The
earth’s crust is 5 km thick below oceans, about 35 km thick below flat
continental surfaces and almost 80 km thick below great mountain ranges.
These are the strong foundations on which mountains stand. The Qur’aan also
speaks about the strong mountain foundations in the following verse: “And
the mountains Hath He firmly fixed.” [Al-Qur’aan 79:32]