The Bay Marchand-Timbalier Bay-Caillou Island salt complex, Louisiana, more than 28 mi long and up to 12 mi wide, may be part of a much longer salt feature that extends both east and west. The mother salt bed, of probable late Triassic-Early Jurassic age, is now buried to depths of 40,000-50,000 ft, whereas the tops of the individual domes along the trend are within 2,000-3,000 ft of the surface.

Production to date on this three-field complex has been in excess of 0.7 billion bbl of oil. Oil reserves are estimated to range from another 0.75 billion to 1 billion bbl. In addition, significant gas reserves are present.

Hydrocarbon accumulations are in sands of Pleistocene through late Miocene age and range in depth from 1,000 to more than 20,000 ft. A wide variety of traps is found, including supradomal arching, shale and salt truncations, stratigraphic traps, and traps resulting from faults.

Production was established on the complex in 1933. The total hydrocarbon production for 1967 was approximately 97 million bbl.