Iranian Plateau

Iranian Plateau 

one of the Southwestern Asian highland regions of Western Asia. The Iranian Plateau is bounded on the north by the Turanian depression and the southern Caspian Lowland; on the east, by the plain of the Indus basin; on the south, by the garmsir, the coastal desert; and on the southwest, by the Mesopotamian lowland. It is contiguous on the west with the Armenian Highlands and on the east with the Pamir mountain region. Approximately 2.7 million sq km in area, the Iranian Plateau extends about 2,500 km from west to east and about 1,500 km from north to south. About two-thirds of the plateau belongs to Iran, while the remainder belongs mainly to Afghanistan and Pakistan. The northern edge of the plateau lies within the USSR (part of the Kopeh Dagh, which is in the Turkmeno-Khorasan mountains), while its western regions are in Iraq.

The Iranian Plateau is typified by complex relief, with a pattern of alternating folded and folded and fault-block mountains and highlands, with accumulative valleys in intermontane depressions. The outlying portions of the Iranian Plateau are subject to alpine orogeny, are experiencing the most recent uplift, and are characterized by high seismicity. Between zones of intensive uplift, there are fold-structured regions of greater age.

Internal regions of the plateau are sharply delineated by peripheral arcs of mountains. In the northern arc lie the Elbrus Mountains, with Mount Demavend (5,604 m), the Turkmeno-Khorasan mountains (including the Kopeh Dagh), the Paropamisus Range and the Hindu Kush (Mount Tirich Mir, 7,690 m). The southern and southwestern arcs are formed by the Zagros (up to 4,548 m, Mount Zard Kuh) and several ranges of the Makran Mountains. On the east of the plateau are the Kir-thar and Sulaiman ranges and the Spin Ghur and Hindu Raj ranges. Within the plateau are several mountain systems (Kuh-rud, Kuhbanan, the Middle Afghans), alternating with plateaus (Sarhad, Ghazni-Kandahar) and vast intermontane closed depressions (Dasht-e Kavir, Dasht-e Lut, Jaz Murian, Sistan, Mashkel). The intermontane depressions are filled with thick strata of friable fragmentary material swept from the surrounding mountains. In the lowest parts of the depressions there are salt and gypsum sedimentary strata formed by the evaporation of lakes, once numerous in these areas.

The climate of the Iranian Plateau is dry and continental to subtropical (with hot summers and relatively cold winters) in the north, and tropical (with a hot summer and warm winter) in the south. Arid conditions prevail, with sparse annual precipitation, varying as a rule from 50 to 150 mm. Only the northern slopes of the Elbrus (to 2,000 mm) and the southwestern flanks and northern extension of the Sulaiman Range (to 1,000 mm) receive adequate rainfall.

The plateau has short, comparatively poor mountain rivers, flowing mainly into closed depressions. The largest are the Karun, Helmand, and Hari; river waters are widely used for irrigation. Lakes, mainly salt lakes (Rezaiyeh, Daryacheh-ye-Namak), are common in internal depressions. The plateau has mainly desert and dry steppe flora on gray desert soils. In the intermontane depressions there are a few large deserts: the salt desert Dasht-e Kavir, the sand deserts Dasht-e Lut and Rege-stan, and the sand and pebble Dasht-e Margo. The steppes, with brown soils, occupy mostly mountain slopes and the interior highlands. Broad-leaved forests on mountain brown forest soils cover the northern slopes of the Elbrus Mountains and the western slopes of the Zagros. On the eastern slopes of the Sulaiman and Kirthar ranges are mountain-savanna landscapes and sparse and subtropical forests with Himalayan cedar and elements of tropical flora.

Rodents and reptiles are the main fauna. There are also many poisonous insects and arachnids (tarantula, karakurt, scorpion). Many migratory birds make their winter home in the lake regions.

REFERENCES

Zarubezhnaia Aziia: Fizicheskaia geografiia. Moscow, 1956.
Petrov, M. P. Iran: Fiziko-geograficheskii ocherk. Moscow, 1955.

M. P. PETROV