Hydrocarbons in rocks of Pleistocene age have been found in 56 fields located mainly offshore from Louisiana. The maximum thickness of the Pleistocene exceeds 10,000 ft (3,050 m) near the outer edge of the continental shelf in the western Gulf basin. The types of lithologies, facies, and traps in which the hydrocarbons accumulated are similar to those of the underlying Pliocene and Miocene beds, which contain major reserves. Additional accumulations are expected to be found in Pleistocene rocks in an area of about 101,000 sq mi (261,160 sq km) offshore from Louisiana and Texas. However, the best opportunity for finding commercial accumulations of oil and gas appears to be in a 4,300-sq mi (11,140 sq km) area in the partially explored Pleistocene province and in a 10,700-s mi (27,710 sq km) area of the unexplored part of the outer continental shelf--a total of 15,000 sq mi (38,850 sq km) with the best potential. The remaining areas, located in the unexplored and partially explored outer continental shelf and on the continental slope, have at best only a speculative potential.