Meaning of salt dome

salt' dome"

Pronunciation: [key]
— Geol. Geol.
  1. a domelike rock structure that is formed beneath the earth's surface by the upward movement of a mass of salt, may reach thousands of feet in vertical extent, and is more or less circular in plan: often associated with oil and gas pools. Cf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.