How do gravity forces help create salt domes?

Gravity forces play a fundamental role in the formation of salt domes through a process of gravitational instability. This occurs when a layer of relatively low-density, plastic material—such as rock salt—is buried beneath denser, heavier sedimentary strata.12

Because the salt is less dense than the overlying rock, it becomes gravitationally unstable and behaves similarly to a fluid, rising toward the surface like cream in milk. Over long periods, and aided by the high pressure and temperature found at depth, the salt flows from its original bed into a rounded salt pillow. As this flow continues, the salt pushes upward, doming the overlying strata and eventually piercing through them to form a plug-shaped mass. This upward migration is a hallmark of diapiric structures, where the mobile salt effectively "pierces" the more brittle surrounding rocks.123