Deserts of the World - Design with the Desert: Conservation and Sustainable Development - page 12

Furthermore, detailed investigations of planktonic foraminifera in the Bay of Bengal 66
indicate high levels of salinity at the time of the Last Glacial Maximum, suggesting that
there was reduced runoff in the Ganga-Brahmaputra at that time, probably as a result of
a less vigorous monsoonal circulation. High-global radiation receipts at around 9000 year
BP caused aridity to be reduced as the vigor of the monsoonal circulation returned. 67

1.5 Arabia and the Middle East
The Middle East is an area of sometimes great aridity and also of great topographic diversity.
On the one hand, there are major mountain ranges: the Zagros and Elburz mountains
of Iran, the Taurus Mountains of Turkey, the Asir Mountains of Arabia, and the Jebel al
Akhdar of Oman. On the other hand, there are the extensive inland plains and plateaus of
Arabia, with their two great sand seas, An Nafud and Rub' al Khali (Figure 1.11), and the
large intermontane basins in which lie the kavirs (salt plains) of Iran.
This topographic diversity owes much to the tectonic history and plate-tectonic setting
of the region. Much of Arabia represents the remnant of part of the ancient landmass of
Gondwanaland, while the mountain ranges are associated with the interaction of three
great plates: the African, the Eurasian, and the Arabian. The Red Sea and the Gulf of Aden
have been formed as the result of sea-floor spreading as Arabia moved away from Africa,
and there has also been about 63 miles of left-lateral movement along the Dead Sea Fault
system since Miocene times, as the Arabian plate has moved northward relative to the
microplate of Sinai. In Iran, the same northward movement of Arabia toward Eurasia has
caused widespread overthrusting, and sediments have been folded into a series of major

Syria

Syrian
Desert

Israel

Iraq

Jordan Iran

Kuwait

An Nafud

Egypt

Qatar

Saudi
Arabia

United Arab
Emirates

Oman

Rub' al Khali

Sudan

Eritrea

Yemen

Djibouti

Indian
Ocean

Ethiopia

Somalia

FIGURE 1.11
Map of the Al Rub' al-Kali (the Empty Quarter) on the Saudi Arabian peninsula.