This paper follows a companion report on the internal structure of the Grand Saline salt dome, Texas. The Jefferson Island salt dome is a slender column, perhaps several miles high, with nearly vertical walls. The megascopic and microscopic features of the salt are described. Salt layers stand vertically, or nearly so. Where the mine exposures approach the southeastern border of the dome, they strike parallel with it. The interior consists of many large and small folds, ranging from open to isoclinal position of the vertical limbs. Near the border, lenses of sandstone have been folded with the salt.

Vertical lineation, shown by distorted halite crystals and preferential orientation of the longest body axes of anhydrite crystals, is common, but there is also coarse-grained, massive salt, locally with large poikiloblasts of halite.

The mode of origin of the salt dome is briefly discussed, with special reference to problems of crystal deformation and recrystallization in salt domes, glaciers, and some granitic massifs.