The Darrow salt dome is located on the east bank of the Mississippi River between Baton Rouge and New Orleans, 30 miles southeast by road from Baton Rouge and 75 miles northwest from New Orleans. It is the first salt dome east of the Mississippi River on which oil in sustained commercial quantities has been produced. The first producer was completed in March, 1933, and on December 31, 1937, the field had a daily production of 2,074 barrels from eight wells, with a total production of 1,518,921 barrels through that date. The proved area at the end of 1937 was about 40 acres, as determined by data from the thirty wells drilled, of which eleven produced oil in some quantity.

Production on the dome has been obtained from super-cap sands and from flank sands, both of which probably represent the same Miocene horizon. A small amount of oil was produced from sands above the cap rock, but the most important production has been secured from what appears to be the same paleontologic horizon faulted to the 5,700-foot and 7,000-foot levels.

The highest part of the dome is 4,627 feet below the surface. At the 6,000-foot contour the salt mass is practically circular in plan with a diameter of 4,800 feet based on present data.

The usual difficulties attendant on pioneer development of piercement-type domes have been experienced in operations at Darrow, among them being the problem of locating the very narrow productive zones, the faulting which has interrupted the peripheral continuity of these sands, and the lack of recognizable datum beds above the oil sands.

The deepest well on the dome was abandoned dry at 7,980 feet in shale of Oligocene age, which is the oldest geologic formation reached on the structure to date.