Minor indications of oil are very widespread, but as yet the only proved oil-fields are at Masjid-i-Sulaiman and Haft Kal, near Shushtar. The production of oil for 1927 was 4,831,800 tons. (See ANGLO-PERSIAN OIL CO., LTD.) Large deposits of salt, gypsum and sulphur are common, but they are only exploited for local use. Precious stones are won on a small scale, rubies near Meshed, turquoise at Maadan near Nishapur and at Khun, south of Jewezm and north of Shahr babek. Iron, ochre and rock salt mines are worked with profit in the Persian gulf.
See A. F. Stahl, Persien, Handbuch der regionalen Geologie, 1911 ; H. de Bockh and others, Tectonics of Asia, British Association, 1928.
(See also PERSIAN GULF, Geology.) (G. M. L.) Physical Geography.—The kingdom of Persia, excepting the lowlands of Khuzistan and the maritime plains bordering the Caspian sea and the Persian gulf, forms the western and larger half of what is known as the great Iranian plateau, raised aloft between the valleys of the Tigris and the Indus. To the north west this plateau is united by the highlands of Armenia with the mountains of Asia Minor, while to the north-east the Paro pamisus range and the Hindu Kush link it with the Himalayas and the highlands of Tibet. Between those zones of connection the plateau is bounded, on the north by the desert steppes of South Russia, Khiva and Bokhara, the scarp being formed by the Kuren and Kopet ranges to the east, and the main Caucasus range to the west, of the intervening depression formed by the Caspian sea. From Mount Ararat south-eastwards the wall of the plateau is formed by the Zagros range and its extensions, running more or less parallel to the course of the river Tigris and the lie of the Persian gulf until they reach the Indo-Persian frontier in Baluchistan. On the east the plateau is bounded by the ranges overhanging the valley of the Indus. The total area
thus enclosed is somewhat over i,000,000 square miles of which • Persia occupies upwards of 600,000. Its average height above sea-level is probably about 4,000 feet, varying from 8,000 ft. or even more in certain of the outer features to not more than 500 in the most depressed portions of the centre. This greatly in creased elevation towards the rim clearly demonstrates the basin like character of the plateau. The lie of the mountain ranges is for the most part from north-west to south-east. The main sys tem, which extelkis almost unbroken for nearly Soo miles, from Azerbaijan to Baluchistan, may aptly be called the Central Range. It has many peaks 9,000 to io,000 feet in height, and some of its summits rise to an elevation of ii,000 feet, and, near Kerman, of nearly 13,00o feet (Kuh-i-Jupar). The valleys and plains west of the Central Range, as for instance those of Mahallat, Joshekan, Isfahan, Sirjan, have an elevation of 5,000 to 6,5oo feet ; those within the range, as Jasp, Ardal, So, Pariz, are about i,000 feet higher; and those east of it slope from an elevation of 5,000 to 6,000 feet down to the depressions of the central plateau which, east of Qum, are not more than 2,600 feet, and east of Kerman 1,500 to 1,700 feet above sea-level. Some of the ranges west of the Central Range, which form the highlands of Kurdistan, Luristan, Bakhtiari and Fars, and are parallel to it, end near the Persian gulf ; others follow the Cen tral Range, and take a direction to the east at some point between Kerman and the sea on the western frontier of Baluchistan. Some of the western ranges rise to considerable elevations; those form ing the Turko-Persian frontier west of the lake of Urmia have peaks 11,000 feet in height, while the Sahand, east of the Lake and south of Tabriz, has an elevation of 12,000 feet. Farther south, the Takht-i-Bilkis, in the Afshar district, rises to 11,200 feet, and the Elvend (ancient Orontes) near Hamadan, to 11,600. The Shuturun Kuh south of Burujird is over 11,000 feet in height, the Shahan Kuh, Kuh-i-Gerra, Zardeh Kuh and Kuh-i Karan, all in the Bakhtiari country west of Isfahan, are 12,800 to 13,00o feet in height.