These are environments where mass quantities of water collect and then evaporate; leaving behind salt and other evaporites to form sedimentary beds.
These places allow salt-bearing water to collect and evaporate, leaving behind bedded deposits of solidified salt crystals.
The second, which is the fact that evaporites are often less dense, or more buoyant, than the surrounding rock, which aids in its mobility and creates a Rayleigh Taylor instability.
In order for originally horizontal beds to form the allochthonous salts, they must first break free of their geological restraints.
[1][2] There is a certain level of transition between the four, as some process, such as the dissolution and removal of salt, deposition of new sediment, erosion and thrusting can shift the characteristics between them.
Salt-wing intrusions are technically underground structures; found in shortening, or compressional, systems, they form radial salt wedges between detached bedding planes.
There are three driving processes in this type of advance; gravitational pressure of both the salt and overlying sediments, spreading of the margin and general plate tectonics.