Probably for the umbilical cord that connects babies (from their early stages in the womb to their removal) to their mothers. The cord is cut, forming the belly button. This is analogous to astronauts in space.
To solve this problem we will apply the concepts related to pressure, depending on the product between the density of the fluid, the gravity and the depth / height at which it is located.
For mercury, density, gravity and height are defined as



For the air the defined properties would be



We have for equilibrium that


Replacing,

Rearranging to find 


Therefore the elevation of the mountain top is 9400ft