The Persian Gulf geosyncline is the result of the pushing southwest of the Alpine arc of the Tauros-Zagros (Kurd) Mountains against the Arabian lobe of the Gondwanda (North African) shield, a stable block creating a great foredeep with more than 30,000 feet of sediments of Carboniferous to Recent beds, principally Cretaceous, Tertiary, and Pliocene in age.

In this basin a considerable number of secondary anticlinal folds constitute the loci of great oil pools, principally now from the Asmari (Eocene-Oligocene) limestone. There are 20 developed oil pools with 150 wells capable of an annual production of 1,600,000 barrels, and much gas; in 1946 production was 729,000 barrels. Northeast of the Zagros Mountains and south of the Elburz Mountains are one second-class and three third-class basins with undeveloped oil possibilities, mostly of Rocky Mountain type.

In southern U.S.S.R. is the Caspian Sea province consisting of three great east-west synclinal basins with beds from Devonian to Recent but principally of Permian to Tertiary strata. Here have been developed the Baku and other fields, but development to date is minor. These basins with extensions westward into Russian-controlled Balkan states and other undeveloped basins, with older beds, at the north, give Russia large oil reserves, though 1946 production was only 555,000 barrels.

The Middle East has 975,000 square miles of oil-gas basins; two-thirds promising for first-class pools. Southern U.S.S.R., inclusive of Balkan areas, has 1,048,000 square miles of primary areas, and 93,000 square miles of secondary areas. Thus, Russia controls in this region alone oil deposits as important as those of the Middle East. It is safe to estimate future ultimate oil reserves of the Middle East and Russia, each at 100 billion barrels, and United States at 50 billion barrels. Of Middle East reserves Britain controls more than United States nationals but they own a somewhat greater area.