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How do salt domes form beneath Earth’s surface?

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Cluster of translucent, white salt crystals with sharp cubic shapes viewed under a microscope at high magnification against a dark background. — salt Salt crystal magnified.

Salt domes form through the movement of relatively plastic materials, such as halite, which flow under high pressure and temperature conditions deep beneath the Earth's surface. This process is driven by gravitational forces—where lighter salt deposits are buried by denser sedimentary strata and rise toward the surface—or by tectonic forces that squeeze the mobile material through less mobile rock.12

The development typically follows a specific sequence:
* Deposition: Thick layers of salt are deposited and subsequently buried by denser sedimentary strata.1
* Pillow Formation: The instability causes the salt to flow into a rounded "salt pillow," which domes the overlying layers and creates a rim syncline in the area where the salt originated.13
* Piercement: Eventually, the salt breaks through the center of the domed strata, forming a plug-shaped mass.1
* Growth: The salt mass continues to move upward as long as there is a supply of salt, often maintaining its position near the surface as additional strata are deposited.1

If the salt supply is exhausted, the growth ceases and the structure becomes buried.1