Bedded salt deposits are nearly horizontal, although some
contain fault zones and other anomalies. Salt beds range in
thickness from a few tens of feet to several thousands of feet.
Salt domes or diapirs formed as salt flowed plastically
(because of pressure and heat) upward through overlying
sediments. The result is a vertically elongated salt deposit of a
mile or more in diameter and perhaps 15,000 to 20,000 feet in
vertical length. The tops of some U.S. gulf coast salt domes
are very near the surface.