The importance of rim synclines, around Gulf Coast salt domes, as structures affecting the migration and accumulation of oil and gas has not been generally recognized. The synclines may divert the migrating oil, in those formations old enough to be affected by subsidence into the syncline, around the dome, and on up dip. They may also overlap with synclines of other domes to form effective traps for the accumulation of oil and gas in the interdomal area. The synclines may be circular, with the dome in the center, circular with the dome in an eccentric position, or irregular in shape, depending largely on the geologic conditions affecting the migration of salt into the dome during the entire history of the growth of the dome.

Differential upward growth of the salt is believed to be caused largely by the differential rate of flow of salt into the dome. Under the resultant forces it is believed that the vertical axis of the dome may migrate a distance as great as the radius of the dome. Such migration of the vertical axis is of interest to the geologist primarily because of the effect it may have on the structure of the oil-bearing formations.