"كتيّب بلاد الرافدين. المجلد I. ١٩١٨" [‎١‎٠] (٥٦٨/١٩)

10 BOUNDARIES AND PHYSICAL FEATURES
of Aleppo, the greater part of the vilayet of Diarbekr, part of the
vilayet of Bitlis, the greater part of the vilayet of Van, the eastern
part of the mutessariflik of Zor, and the vilayets of Mosul, Baghdad,
and Basra. On its south-eastern side, from the southern end of the
Avroman Dagh to the Persian Gulf, it takes in a belt of Persian
territory, namely the western part of the province of Kirmanshah,
the Pusht-i-Kuh country and part of southern Luristan, the provinces
of northern and southern Arabistan, the plain of Behbehan, and the
Bakhtiyari and Kuhgalu countries.
Main Features op Surface
The area as a whole may be regarded as a great depression running
SSE. from the northern corner of Syria and the high plateaux of Ana
tolia and Armenia down to the head of the Persian Gulf. The eastern
side of this depression is formed by the mountainous edge of the
Persian plateau, the western and south-western side by the gradual
slope of the Syrian and Arabian Deserts, which fall towards the
Euphrates valley from the highlands of Syria and the plateau
of Arabia,
Under the high mountains which enclose Mesopotamia on the north
and east is a belt of lower hill-country, varying in breadth roughly
from 40 to 100 miles, and below this again are the Mesopotamian
plains, which form the floor of the depression. To the west and south
west of these, along the right side of the Euphrates valley, rise the
low cliffs or hills which are the border of the desert.
The plains thus bounded have a total area of about 112,000 square
miles. From their northern end down to the flat shores of the
Persian Gulf they fall some 1,100-1,400 ft. in 650-700 miles.
The upper plain-country between the northern hill-belt and the
neighbourhood of Baghdad has a fall of about 900-1,200 ft. in 350-
450 miles. Its undulating surface is composed of sedimentary forma
tions, and is traversed here and there (especially in its northern
part) by chains of sandstone, gypsum, or basalt hills.
Not far to the north of Baghdad the upper plains end in a drop of
20-50 ft. (which marks a former coast-line), and the great alluvial
plain of Irak, formed by the Euphrates and the Tigris, begins. The
alluvium of Irak stretches down to the head of the Persian Gulf,
falling a little over 100 ft. in 300-350 miles. Towards the south
east the Irak plain is continued by the alluvial lands of Arabistan
created by the Karun and by the smaller streams of the Jerrahi and
the Hindlyan. The total area of the alluvial plains is about 50,000-
55,000 square miles.