The Misconception of Pressure-Driven Drainage
It is intuitive to think that high pressure forces water out. However, pressure is a measure of force per unit area. For water to flow *into* the ground, there must be a permeable path—a network of connected pores or cracks—for the water to move through. If the rock is impermeable (as we learned in Chapter 3), the water has nowhere to go. The pressure simply pushes against the rock walls, but since the rock is solid and rigid, the water cannot penetrate it.
The Inflated Balloon Analogy
Think of an inflated balloon. The air inside is under high pressure, pushing outward against the rubber skin. Yet, the air does not leak out because the rubber is impermeable. Similarly, the deep ocean water is under high pressure, pushing against the seafloor. Because the basalt and shale beneath are impermeable, the water stays put, just as the air stays in the balloon.
Equilibrium State
The ocean floor is in a state of hydrostatic equilibrium. The downward force of gravity (weight of the water) is perfectly balanced by the upward structural resistance of the impermeable rock. No net movement occurs because there is no permeable outlet.