Internally, salt stocks consist of isoclinal, attenuated, vertically plunging, refolded, and faulted folds resembling those in a handkerchief drawn vertically from the center through a small ring. Folding is by flowage, not flexural bending; folds are correspondingly complex and attenuated, but uniaxial. Interbedded detrital sediments and nonhalite salts may have been eliminated during movement. Strain hardening of halite crystals as well as differential sedimentation rates may have caused movements to be intermittent in space as well as in time, and strongly affected internal structures. External structures, such as grabens and faults, may be related to internal structures, such as faults, shears, and zones of differential movement. Cooperation is needed between petroleu geologists and salt-fabric geologists to determine the origin of salt massifs, overhangs, spines, and intermittent salt movements.