Internally, salt stocks consist of isoclinal, attenuated, vertically-plunging, complex folds and resemble a handkerchief drawn vertically through a small ring. They appear to have developed by intermittent and shifting movements which may have been controlled largely by strain hardening of halite crystals and varying rates of sedimentation. These movements must have strongly affected external structures and oil migration. External structures, like grabens and faults, may be related to internal structures like zones of shearing and differential movement (faulting?). Close cooperation among petroleum geologists, geophysicists, and salt-fabric geologists is needed if we are to decipher the origin of salt massifs, salt spines, overhangs, and intermittent salt movements.

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