It is of interest to examine the nature and origin of certain breccia textures observed on polished surfaces of side-wall cores from wells on the flanks of salt domes in the southern Louisiana area. The textures occur in the shales of an intercalated shale-sandstone sequence which extends thousands of feet both horizontally and vertically. The breccia is considered to result from differential movement throughout a broad dome-shaped mass with the salt plug at the center. Microscopic, megascopic, and physical studies establish the texture as an inherent feature of the shale and not an impact effect of the coring mechanism.

The breccia appears significantly different from well known types ordinarily recognized in sediments as illustrated by subaerial, tectonic, glide, desiccation, and intraformational breccias. The term "salt-dome breccia" is suggested by the proximity of breccias to salt-dome areas. It appears distinct from the local breccia of the sheath.

The texture is believed to be developed by differential movement throughout the sedimentary mass. It accompanies the emplacement of the salt plug and appears in shale consisting essentially of clay-mineral aggregates. It occurs at depths where the shale is dry enough to provide adequate rigidity to register brecciation.