Overhanging cap rock and salt were discovered on this dome in January, 1930, when a well on encountering salt was drilled deeper through more than 800 feet of salt into the sedimentary beds below. Up to the present, fifty-two wells have been drilled through the cap rock and salt. The greatest thickness of salt penetrated was 2,419 feet.

The overhang is shallowest on the north, east, and south flanks, where drilling has shown that it projects outward distances ranging from 400 feet to 1,300 feet. The projection of the cap rock and salt on the west flank lies much deeper below the surface and has had very little exploration.

The movement producing the overhang seems to have disturbed only slightly the prolific oil sands of the Miocene and Oligocene ages lying below it.

Three general theories of the origin of salt-dome overhangs are given: upward and outward movement of the salt; downbuilding of salt domes; and solution of salt on the flanks. The writers believe that the first of these was the main cause of the overhang at Barbers Hill, and that the third was a lesser contributing factor.

The discovery of the overhang has uncovered reserves of oil sufficiently large to establish Barbers Hill as one of the major producing domes of the Gulf Coast.