Question

Assuming that local continental crust has a thickness of 30 km when it is at sea level, and assuming the mantle has a density of 3300 kg/m³, how deep (in meters) is the root beneath a mountain of height 1,800m and density 2750 kg/m³? (In other words, how much deeper is the crust beneath the mountain than “regular” crust?). Over time, the mountain erodes to a height of 1.2 km. How deep were the rocks now exposed at the surface when the mountain was at its original height?

Answer 1

​​when the hight of the mountain is 1800m then root beneath the crust is 10080m.

When the rock erode then rock is not suddenly comes up, so root beneath the earth approximately same. Because rock beneath the crust is undercomponsation.